290 results
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2. Kinetogami: A Reconfigurable, Combinatorial, and Printable Sheet Folding.
- Author
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Wei Gao, Karthik Ramani, Raymond J. Cipra, and Thomas Siegmund
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PAPER arts , *ORIGAMI , *ART & mathematics , *ENGINEERING , *FOOD packaging , *HINGES - Abstract
As an ancient paper craft originating from Japan, origami has been naturally embedded and contextualized in a variety of applications in the fields of mathematics, engineering, food packaging, and biological design. The computational and manufacturing capabilities today urge us to develop significantly new forms of folding as well as different materials for folding. In this paper, by allowing line cuts with crease patterns and creating folded hinges across basic structural units (BSU), typically not done in origami, we achieve a new multiprimitive folding framework such as using tetrahedral, cuboidal, prismatic, and pyramidal components, called “Kinetogami.” “Kinetogami” enables one to fold up closed-loop(s) polyhedral mechanisms (linkages) with multi-degree-of-freedom and self-deployable characteristics in a single build. This paper discusses a set of mathematical and design theories to enable design of 3D structures and mechanisms all folded from preplanned printed sheet materials. We present prototypical exploration of folding polyhedral mechanisms in a hierarchical manner as well as their transformations through reconfiguration that reorients the material and structure. The explicit 2D fabrication layout and construction rules are visually parameterized for geometric properties to ensure a continuous folding motion free of intersection. As a demonstration artifact, a multimaterial sheet is 3D printed with elastomeric flexure hinges connecting the rigid plastic facets. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
3. Pneumatic Variable Series Elastic Actuator
- Author
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Molei Wu, Xiangrong Shen, and Hao Zheng
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0209 industrial biotechnology ,Engineering ,Plant ,02 engineering and technology ,Computer Science::Robotics ,03 medical and health sciences ,020901 industrial engineering & automation ,0302 clinical medicine ,Motor controller ,Control theory ,medicine ,Instrumentation ,Equilibrium point ,Pneumatic actuator ,business.industry ,Pressure control ,Mechanical Engineering ,Motor control ,Stiffness ,Control engineering ,Research Papers ,Computer Science Applications ,Control and Systems Engineering ,medicine.symptom ,business ,Actuator ,030217 neurology & neurosurgery ,Information Systems - Abstract
Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to closed-loop control, and suffers from multiple issues such as limited frequency range, potential instability, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elastic actuator (VSEA), leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modeled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on–off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.
- Published
- 2016
4. Development and Feasibility of a Robotic Laparoscopic Clipping Tool for Wound Closure and Anastomosis
- Author
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Justin D. Opfermann, Axel Krieger, and Peter C.W. Kim
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Engineering ,Forceps ,education ,Biomedical Engineering ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Medicine (miscellaneous) ,030230 surgery ,Anastomosis ,Bench test ,03 medical and health sciences ,0302 clinical medicine ,cardiovascular diseases ,CLIPS ,Simulation ,computer.programming_language ,ComputingMethodologies_COMPUTERGRAPHICS ,business.industry ,Robotics ,Research Papers ,nervous system diseases ,surgical procedures, operative ,030220 oncology & carcinogenesis ,cardiovascular system ,Wound closure ,Artificial intelligence ,business ,computer ,Robotic arm - Abstract
This paper reports the design, development, and initial evaluation of a robotic laparoscopic clipping tool for single manipulator wound closure and anastomosis (tubular reconnection). The tool deploys biodegradable clips and clasps with the goal of (i) integrating grasping and suturing into a single device for single hand or manipulator use, (ii) applying the equivalent of interrupted sutures without the need of managing suture thread, and (iii) allowing for full six degrees-of-freedom (DOFs) laparoscopic control when mounted on a robot arm. The specifications, workflow, and detailed design of the robotic laparoscopic tool and injection molded bio-absorbable T shaped clip and locking clasp are reported. The clipping tool integrates forceps to grab and stabilize tissue and a clip and clasp applier to approximate and fixate the tissue. A curved needle is advanced on a circular needle path and picks up and drags clips through tissue. The clip is then tightened through the tissue and a clasp is clamped around the clip, before the clip is released from the needle. Results of several bench test runs of the tool show: (a) repeatable circular needle drive, (b) successful pick-up and deployment of clips, (c) successful shear of the clip to release the clip from the needle, and (d) closure of clasp on clip with an average of 2.0 N holding force. These data indicate that the robotic laparoscopic clipping tool could be used for laparoscopic wound closure and anastomosis.
- Published
- 2017
5. Improving Biomedical Engineering Education Through Continuity in Adaptive, Experiential, and Interdisciplinary Learning Environments
- Author
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Dawn Ferry, Anita Singh, and Susan Mills
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Engineering ,business.industry ,0206 medical engineering ,05 social sciences ,Biomedical Engineering ,050301 education ,Interdisciplinary learning ,02 engineering and technology ,Problem-Based Learning ,020601 biomedical engineering ,Experiential learning ,Research Papers ,Biomechanical Phenomena ,Patient safety ,Physiology (medical) ,Health care ,ComputingMilieux_COMPUTERSANDEDUCATION ,Capstone ,Interdisciplinary Communication ,Engineering principles ,business ,0503 education ,Adaptive expertise ,Inclusion (education) ,Biomedical engineering - Abstract
This study reports our experience of developing a series of biomedical engineering (BME) courses having active and experiential learning components in an interdisciplinary learning environment. In the first course, BME465: biomechanics, students were immersed in a simulation laboratory setting involving mannequins that are currently used for teaching in the School of Nursing. Each team identified possible technological challenges directly related to the biomechanics of the mannequin and presented an improvement overcoming the challenge. This approach of exposing engineering students to a problem in a clinical learning environment enhanced the adaptive and experiential learning capabilities of the course. In the following semester, through BME448: medical devices, engineering students were partnered with nursing students and exposed to simulation scenarios and real-world clinical settings. They were required to identify three unmet needs in the real-world clinical settings and propose a viable engineering solution. This approach helped BME students to understand and employ real-world applications of engineering principles in problem solving while being exposed to an interdisciplinary collaborative environment. A final step was for engineering students to execute their proposed solution from either BME465 or BME448 courses by undertaking it as their capstone senior design project (ENGR401-402). Overall, the inclusion of clinical immersions in interdisciplinary teams in a series of courses not only allowed the integration of active and experiential learning in continuity but also offered engineers more practice of their profession, adaptive expertise, and an understanding of roles and expertise of other professionals involved in enhancement of healthcare and patient safety.
- Published
- 2018
6. Miura-Base Rigid Origami: Parameterizations of First-Level Derivative and Piecewise Geometries.
- Author
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Joseph M. Gattas, Weina Wu, and Zhong You
- Subjects
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ORIGAMI , *PAPER arts , *PARAMETERIZATION , *ARCHITECTURAL decoration & ornament , *ENGINEERING , *GEOMETRIC modeling - Abstract
Miura and Miura-derivative rigid origami patterns are increasingly used for engineering and architectural applications. However, geometric modelling approaches used in existing studies are generally haphazard, with pattern identifications and parameterizations varying widely. Consequently, relationships between Miura-derivative patterns are poorly understood, and widespread application of rigid patterns to the design of folded plate structures is hindered. This paper explores the relationship between the Miura pattern, selected because it is a commonly used rigid origami pattern, and first-level derivative patterns, generated by altering a single characteristic of the Miura pattern. Five alterable characteristics are identified in this paper: crease orientation, crease alignment, developability, flat-foldability, and rectilinearity. A consistent parameterization is presented for five derivative patterns created by modifying each characteristic, with physical prototypes constructed for geometry validation. It is also shown how the consistent parameterization allows first-level derivative geometries to be combined into complex piecewise geometries. All parameterizations presented in this paper have been compiled into a matlab Toolbox freely available for research purposes. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
7. On the Advantages of Searching Infeasible Regions in Constrained Evolutionary-Based Multi-Objective Engineering Optimization.
- Author
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Dwianto, Yohanes Bimo, Palar, Pramudita Satria, Zuhal, Lavi Rizki, and Oyama, Akira
- Subjects
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EVOLUTIONARY algorithms , *ENGINEERING , *PROBLEM solving , *ENGINEERING design - Abstract
Solving a multiple-criteria optimization problem with severe constraints remains a significant issue in multi-objective evolutionary algorithms. The problem primarily stems from the need for a suitable constraint handling technique. One potential approach is balancing the search in feasible and infeasible regions to find the Pareto front efficiently. The justification for such a strategy is that the infeasible region also provides valuable information, especially in problems with a small percentage of feasibility areas. To that end, this paper investigates the potential of the infeasibility-driven principle based on multiple constraint ranking-based techniques to solve a multi-objective problem with a small feasibility ratio. By analyzing the results from intensive experiments on a set of test problems, including the realistic multi-objective car structure design and actuator design problem, it is shown that there is a significant improvement gained in terms of convergence by utilizing the generalized version of the multiple constraint ranking techniques. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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8. Understanding Frugal Engineering for Equity: Exploring Convergence of Biological Designs and Social Innovations.
- Author
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Malshe, Ajay P., Bapat, Salil, and Fischer, Lukas
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SOCIAL innovation , *COMMUNITIES , *TECHNOLOGICAL innovations , *SUSTAINABILITY , *ENGINEERING , *TECHNOLOGY convergence , *ICE , *WATER use , *REMANUFACTURING - Abstract
Multiple global trends and drivers have resulted in a steep escalation of tech-socio-economic inequities in basic human needs across industrialized as well as industrializing nations. This escalation is paralleled by the growing trend of novel and simple frugal innovations for meeting basic human needs, which are applied across various communities in the world towards bridging gaps of inequity. Frugality in this context is defined as minimizing the use of capital resources while delivering effective manufacturing product outcomes. It is noteworthy that frugal innovations are abundantly observed in the biological designs in nature. This paper is aimed at understanding the methodology of frugal engineering behind the resulting frugal manufacturing innovations through discovering the cross-section of frameworks of biological designs in nature and equitable social innovations. Authors have applied the framework of biological designs as these designs are observed to deliver multifunctionality, resilience, and sustainability, which are key to a frugal and equitable innovation platform and achieved by the frugal engineering process. As water is one of the most basic human needs, this paper uses water as an illustrative example to understand the frugal engineering process. The authors discuss designs in nature from cactus, tree roots, and human skin, and design parallels in related frugal innovations namely in fog-capturing nets, ice stupa, and Zeer (pot-in-a-pot), respectively, for equitable water access. The authors propose and discuss a resulting methodology for frugal engineering. This methodology can be utilized as a starting point for developing case-specific socially conscious manufacturing solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. WATER PAPER GLASS.
- Author
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Sharke, Paul
- Subjects
LENSES ,OPTICAL instruments ,OPTICS ,DIGITAL photography ,ENGINEERING - Abstract
Scientists and engineers at Royal Philips Electronics NV of the Netherlands are developing a fluid lens that loosely duplicates the way in which they see with their own eyes. Called the FluidFocus lens, it focuses by adjusting the shape of the lens itself. According to the company, the lens may eventually fill applications in digital photography, endoscopy, home security, and optical storage. The lens, filled with one part insulating oil and one part conductive aqueous solution, forms a hemispheric bubble in the unenergized state as the hydrophobic sides repel the water and oil fills the void.
- Published
- 2004
- Full Text
- View/download PDF
10. Design of Revolute Joints for In-Mold Assembly Using Insert Molding
- Author
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Leicester Ehrlich, Satyandra K. Gupta, Jaydev P. Desai, and Arvind Ananthanarayanan
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Engineering ,Insert (composites) ,business.industry ,Medical robot ,Mechanical Engineering ,Process (computing) ,Mechanical engineering ,Molding (process) ,Revolute joint ,Computer Graphics and Computer-Aided Design ,Research Papers ,Computer Science Applications ,Mechanics of Materials ,Robot ,Torque ,business ,Joint (geology) - Abstract
Creating highly articulated miniature structures requires assembling a large number of small parts. This is a very challenging task and increases cost of mechanical assemblies. Insert molding presents the possibility of creating a highly articulated structure in a single molding step. This can be accomplished by placing multiple metallic bearings in the mold and injecting plastic on top of them. In theory, this idea can generate a multi degree of freedom structures in just one processing step without requiring any post molding assembly operations. However, the polymer material has a tendency to shrink on top of the metal bearings and hence jam the joints. Hence, until now insert molding has not been used to create articulated structures. This paper presents a theoretical model for estimating the extent of joint jamming that occurs due to the shrinkage of the polymer on top of the metal bearings. The level of joint jamming is seen as the effective torque needed to overcome the friction in the revolute joints formed by insert molding. We then use this model to select the optimum design parameters which can be used to fabricate functional, highly articulating assemblies while meeting manufacturing constraints. Our analysis shows that the strength of weld-lines formed during the in-mold assembly process play a significant role in determining the minimum joint dimensions necessary for fabricating functional revolute joints. We have used the models and methods described in this paper to successfully fabricate the structure for a minimally invasive medical robot prototype with potential applications in neurosurgery. To the best of our knowledge, this is the first demonstration of building an articulated structure with multiple degrees of freedom using insert molding.
- Published
- 2011
11. Development of a Portable Knee Rehabilitation Device That Uses Mechanical Loading
- Author
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Todd Dodge, Daric Fitzwater, Stanley Chien, Sohel Anwar, and Hiroki Yokota
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Bone growth ,Engineering ,Modality (human–computer interaction) ,Human studies ,business.industry ,Biomedical Engineering ,Medicine (miscellaneous) ,Usability ,Research Papers ,Loader ,Duty cycle ,Knee rehabilitation ,business ,Actuator ,Simulation - Abstract
Joint loading is a recently developed mechanical modality, which potentially provides a therapeutic regimen to activate bone formation and prevent degradation of joint tissues. To our knowledge, however, few joint loading devices are available for clinical or point-of-care applications. Using a voice-coil actuator, we developed an electromechanical loading system appropriate for human studies and preclinical trials that should prove both safe and effective. Two specific tasks for this loading system were development of loading conditions (magnitude and frequency) suitable for humans, and provision of a convenient and portable joint loading apparatus. Desktop devices have been previously designed to evaluate the effects of various loading conditions using small and large animals. However, a portable knee loading device is more desirable from a usability point of view. In this paper, we present such a device that is designed to be portable, providing a compact, user-friendly loader. The portable device was employed to evaluate its capabilities using a human knee model. The portable device was characterized for force-pulse width modulation duty cycle and loading frequency properties. The results demonstrate that the device is capable of producing the necessary magnitude of forces at appropriate frequencies to promote the stimulation of bone growth and which can be used in clinical studies for further evaluations.
- Published
- 2013
12. Effect of Indium Content on the Melting Point, Dross, and Oxidation Characteristics of Sn-2Ag-3Bi-xIn Solders
- Author
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Chung-Yun Kang, Sang-hoon Lee, Ae-jeong Jeon, and Seong-Jun Kim
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Auger electron spectroscopy ,Materials science ,Dross ,Alloy ,Metallurgy ,chemistry.chemical_element ,Solidus ,Liquidus ,engineering.material ,Research Papers ,Computer Science Applications ,Electronic, Optical and Magnetic Materials ,chemistry ,Mechanics of Materials ,engineering ,Melting point ,Wetting ,Electrical and Electronic Engineering ,Indium - Abstract
This paper presents the effect of indium (In) content on the melting temperature, wettabililty, dross formation, and oxidation characteristics of the Sn-2Ag-3Bi-xIn alloy. The melting temperature of the Sn-2Ag-3Bi-xIn alloy (2 ≤ x ≤ 6) was lower than 473 K. The melting range between the solidus and liquidus temperatures was approximately 20 K, irrespective of the indium content. As the indium content increased, the wetting time increased slightly and the maximum wetting force remained to be mostly constant. The dross formation decreased to approximately 50% when adding 1In to Sn-2Ag-3Bi, and no dross formation was observed in the case of Sn-2Ag-3Bi-xIn alloy (x ≥ 1.5) at 523 K for 180 min. Upon approaching the inside of the oxidized solder of the Sn-2Ag-3Bi-1.5In alloy from the surface, the O and In contents decreased and the Sn content increased based on depth profiling analysis using Auger electron spectroscopy (AES). The mechanism for restraining dross (Sn oxidation) of Sn-2Ag-3Bi alloy with addition of indium may be due to surface segregation of indium. This is due to the lower formation energy of indium oxide than those of Sn oxidation.
- Published
- 2013
13. Study of Using Solar Thermal Power for the Margarine Melting Heat Process
- Author
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Mohamed A. Sharaf Eldean and Ahmed Soliman
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Engineering ,Waste management ,Renewable Energy, Sustainability and the Environment ,business.industry ,Photovoltaic system ,Energy Engineering and Power Technology ,Thermal power station ,Solar energy ,Thermal energy storage ,Research Papers ,Renewable energy ,Photovoltaic thermal hybrid solar collector ,business ,Solar desalination ,Thermal energy - Abstract
Margarine as a raw material has a multiple uses in the production of bio-organic materials such as refined oil and butter. It passes through many industrial stages before beginning the process of refining and packaging it to the consumer. One of these important stages is the melting process, which wastes an immense amount of thermal power. The large rate of thermal power consumption occurs due to the huge reservoirs in which the margarine is stored (500 m3–1500 m3 Savola International Company-Suez Gulf region-Egypt). With drawing margarine from the reservoirs is a cost and time intensive process due to the solid state of margarine at environmental temperatures. Dry saturated steam is passed through the heat exchanger pipes inside the reservoir to melt the required amount of margarine. In some cases, this process can take up to 8 h in the summer and 12 h in the winter, which can be amplified by the loss of heat energy from the reservoir throughout the day, especially during the night periods. Moreover, steam boilers that use heavy fuel or natural gas can cause serious environmental damage as a result of emissions, such as the carbon oxide and nitrous oxide compounds. In contrast, solar energy is one of the cleanest and environmentally friendly renewable energies and should be invested as an alternative heat source for the melting process of margarine. As mentioned before, the melting of margarine is considered a heating process that consumes a huge amount of thermal energy. Therefore, solar thermal power can play a vital role in the process of melting margarine. Generally, temperature requirements of solar industrial heat applications range from 60 °C to 260 °C. Cylindrical PTC systems look very promising for delivering industrial heating process applications in the range of 95 °C–350 °C delivery temperature [1]. For solar thermal applications, the operating design conditions of solar collectors should be well above the desired operating conditions of the application to ensure stability of the operation. Therefore, flat plate collectors and evacuated tube collectors are eliminated from this study due to the previous reason and its lower efficiencies compared against the PTC [2]. This is why medium to medium–high temperature solar collectors are used [3,4]. Most of the production processes of the food industry such as milk products, vegetable, meat, fruits, and beer are run at temperatures below or near 100–130 °C. In addition, many cleaning processes such as pasteurizing, sterilizing, drying, hydrolyzing, distillation, washing, polymerization, and cooking processes are conducted under thermal applications [5,6]. Thus, switching to a renewable energy source, such as solar energy, can result in cost savings as well as decrease the negative impacts the production process has on the environment. The production process of margarine requires a large amount of heat in which solar thermal power is a viable and more cost effective source of energy. The problem originally emerged when Savola's company officials (Savola International Company in Margarine industrial Suez Gulf region-Egypt) decided to optimize the time, energy, and cost of the production process. They summarized their problems into the following points: The process of margarine melts takes more than 12 h to obtain 100–200 m3 of melted margarine per day. Which costs the equivalent amount of 476,120 m3 per day of natural gas (100,000 $/month). Reduction of CO2, NO2, and CO emissions is a must according to environmental laws. After reviewing the configuration of their heating process, using solar thermal power as a clean energy alternative seemed to be the most viable solution. Egypt has a great potential for solar energy. It is calculated that an amount of 6–7 kW h/m2/day of global radiation is in the Suez Gulf region-Egypt [8]. Therefore, it is very promising to utilize this vast amount of untapped solar energy in this industrial heating process. The aim of this research is to present a feasibility study, assessing the impact of using solar thermal power as an alternative source of energy in the margarine melting process. In this study, solar PTC is used instead of a conventional steam boiler. Water–steam and/or Therminol-VP1 [7] HTO are utilized through the PTC representing two different configurations. The data results of the conventional configuration (config1) are compared with the PTC–water steam configuration (config2) and PTC–Therminol configuration (config3) according to the hourly cost parameter ($/h). The study plan is organized as follows: The process configurations for the proposed systems are performed and the design limits are investigated. The mathematical model that represents the proposed systems is constructed. Three cases are compared (solar direct vapor generation (two configurations) was conventional configuration). Practical and analytical solutions for the process problems are studied and executed. solar desalination system (SDS) software package (a part of renewable energy desalination system (REDS) that were developed by the authors) was used to model all the system units [8–11]. 2. Margarine Melting Heating Process 2.1. The Process Problems. The problem began when Savola's-Egypt officials decided to evaluate the productive performance of their company. In their current configuration, a steam boiler running on fuels is used in the heating process. The company was faced with several problems identified as below. Wasted time, especially in the winter it requires melting about 100–300 m3 within approximately 12 h. This requires a significant amount of time before the canning process can begin. In addition, the steam boiler has to be operated during night hours to collect the melted margarine early in the morning before the canning process. It is noted that the fuel consumption is also very high, especially in the case of heavy fuel operations. As the average daily consumption reached 1 m3 or more, which is considered to be a high rate of consumption. The exhaust emissions resulting from the combustion inside the steam boiler today are unacceptable in the light of international regulations which intend to reduce global carbon emissions. Because of the temperature difference during the night especially in winter a large amount of thermal power gets wasted. This increases the operation time and the rate of fuel consumption. Thus, Savola's Egyptian officials contacted the authors to investigate and propose solutions to the existing inefficiencies, while at the same time decreasing the negative impact on the environment.
- Published
- 2014
14. Computationally Efficient Magnetic Resonance Imaging Based Surface Contact Modeling as a Tool to Evaluate Joint Injuries and Outcomes of Surgical Interventions Compared to Finite Element Modeling
- Author
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Phil Lee, Kenneth J. Fischer, E. Bruce Toby, Terence E. McIff, and Joshua E. Johnson
- Subjects
Adult ,Male ,Wrist Joint ,Engineering ,Finite Element Analysis ,Biomedical Engineering ,Kinematics ,Wrist ,Young Adult ,Physiology (medical) ,medicine ,Pressure ,Humans ,Displacement (orthopedic surgery) ,Computer Simulation ,Joint (geology) ,Mechanical Phenomena ,business.industry ,Biomechanics ,Middle Aged ,Rigid body ,Wrist Injuries ,Research Papers ,Magnetic Resonance Imaging ,Finite element method ,Biomechanical Phenomena ,Contact mechanics ,medicine.anatomical_structure ,Treatment Outcome ,Feasibility Studies ,business ,Biomedical engineering - Abstract
Computational modeling is very useful in biomechanics to simulate normal and pathologic joint function. It is also useful to determine the efficacies of various surgical procedures performed to treat joint pathologies and simulate their outcomes. Models can be used to estimate in situ measures such as contact pressure distributions that are difficult to acquire through experiments noninvasively. Currently, computational modeling is the only technique available to noninvasively evaluate in vivo joint contact mechanics [1]. However, most models make use of input parameters derived from various general sources such as literature, standards, or experiments and are, therefore, limited for patient-specific applications [2]. Joint injuries, whether ligaments or articular surface, are a significant problem and there is still a need for tools to effectively evaluate joint injuries and associated sequelae [3]. The ability to monitor the initiation and progression of joint instability after injury may aid in determining prognosis, leading to better treatment algorithms. In order to refine or develop treatments that are targeted toward individuals, it is important to focus on subject-specific models. Several modeling techniques exist to evaluate in vivo joint mechanics. The common techniques include image-based FEM [4–13], rigid body spring modeling/discrete element analysis (RBSM) [14–16], or SCM [17–19]. The models are either displacement driven or force driven. Generally, model geometries are acquired from modalities such as computed tomography (CT) [4–8,14,15,19] or MRI [9–11,17,18]. Kinematics are determined through external (surface markers) or internal (biplanar radiography) measures, while tendon forces are estimated from corresponding musculature electromyography (EMG) and cross-sectional area, and ground reaction forces are measured using force platforms [11,20]. These loads and displacement boundary conditions are input into the model to infer joint kinetics/kinematics and resulting surface and/or volumetric stresses and strains. FEM is the most common and accurate method to determine stresses [11,20,21]. However, depending on the complexity of the problem, the process of developing the mesh can be laborious and obtaining a converged solution can be computationally intensive [22], which limits its clinical applicability. Depending on the type of problem (for instance, deformable versus rigid), more simplified analyses can be performed based on relevant assumptions to determine appropriate solutions. This is the basis of RBSM and SCM techniques. Using these methods, joint mechanics can be evaluated in a computationally efficient manner compared to FEM [23], which makes them relevant for clinical applications. The underlying question is whether these methods are competent to provide data that are sufficiently accurate for the intended application. The ability to accurately determine joint mechanics has wide clinical implications, especially in complex joints such as the wrist. It may be possible to sufficiently evaluate changes in joint mechanics as a result of injury or surgical intervention from surface contact mechanics data alone. This can be achieved through the SCM technique, without the need for a complex volumetric analysis [24]. However, the SCM technique has not been extensively used for orthopedic applications. Computational modeling has been extensively applied to the lower extremity to evaluate in vivo joint mechanics [4–11,18]. In the wrist, studies have evaluated in vivo joint mechanics during functional activities [12,14,16,17] and have also simulated the effects of some carpal fractures and limited fusions [13,15,19]. Scapholunate (SL) ligament injury is a commonly occurring wrist ligament injury that can lead to SL joint instability and progressive degenerative changes [25–28]. Prior modeling work on the in vivo effects of SL ligament injury or surgical repair appears to be limited [29,30]. Hence, we investigated differences in radiocarpal in vivo joint mechanics obtained from SCM for normal wrists, after SL ligament injury, and after surgical repair to results from the FEM “gold standard.” We did not intend to make comparisons between the normal, injured, and postoperative states. Our goal was to show that contact outcomes obtained from SCM would be comparable to those obtained from a similar FEM analysis regardless of wrist state and to demonstrate the feasibility and applicability of the SCM technique.
- Published
- 2014
15. Critical Damping Conditions for Third Order Muscle Models: Implications for Force Control
- Author
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Ferdinando A. Mussa Ivaldi, Alberto Pierobon, and Davide Piovesan
- Subjects
Engineering ,Posture ,Biomedical Engineering ,Internal model ,Models, Biological ,Tendons ,Weight-Bearing ,Control theory ,Physiology (medical) ,medicine ,Humans ,Isotonic Contraction ,Muscle, Skeletal ,business.industry ,Biomechanics ,Motor control ,Stiffness ,food and beverages ,Robotics ,Muscle stiffness ,Research Papers ,Elasticity ,Biomechanical Phenomena ,Mechanical system ,Third order ,Linear Models ,Artificial intelligence ,Stress, Mechanical ,medicine.symptom ,business ,Muscle Contraction - Abstract
One's ability to exert controlled forces on the environment, such as when manipulating fragile objects, is very important in everyday life. This suggests that force regulation is a necessary component of motor control. In robotics, an effective way to implement force control is by imposing a low contact impedance with critical damping, and using admittance control to regulate force output [1,2]. Human limbs can be modeled as second order mechanical systems, under the assumption that tendons are much stiffer than muscle fibers. The mechanical properties of muscle fibers alone render the implementation of the aforementioned direct force control strategy as not efficient. Several studies have demonstrated that the exertion of force onto the environment results in an increase in muscle stiffness [3–5] and a reduction of muscle damping to under critical values [6,7]. Modeling tendons and contractile elements independently requires higher than second order muscle-tendon models [8]. The presence of a tendon elastic element favors an oscillatory response to external disturbances that normally needs to be eliminated [9]. We demonstrated that a higher order model always exhibits an oscillatory free response and cannot be critically dampened for mechanical parameters included within the normal physiological range. This requires the force controller implemented by the central nervous system (CNS) to employ active feedback and feed-forward regulation. We propose that oscillations, whether part of an external disturbance or of the system's response, can be actively compensated for by the CNS with a position control approach, as long as a predictive model of the perturbation, and an internal model of the system's biomechanics are available. This model of control is in agreement with findings previously published by our group that showed how the implementation of an internal feed-forward model trajectory can be part of a force-regulation strategy [10].
- Published
- 2013
16. Robust Identification of Three-Dimensional Thumb and Index Finger Kinematics With a Minimal Set of Markers
- Author
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Raviraj Nataraj and Zong Ming Li
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Adult ,Male ,Engineering ,Motion analysis ,Movement ,Coordinate system ,Biomedical Engineering ,Kinematics ,Thumb ,Motion capture ,Young Adult ,Physiology (medical) ,Finger Joint ,medicine ,Humans ,Computer Simulation ,Simulation ,Mechanical Phenomena ,Inverse kinematics ,Hand Strength ,business.industry ,Index finger ,Research Papers ,Biomechanical Phenomena ,body regions ,medicine.anatomical_structure ,Finger joint ,Female ,business ,Algorithm - Abstract
This study presents a methodology to determine thumb and index finger kinematics while utilizing a minimal set of markers. The motion capture of skin-surface markers presents inherent challenges for the accurate and comprehensive measurement of digit kinematics. As such, it is desirable to utilize robust methods for assessing digit kinematics with fewer markers. The approach presented in this study involved coordinate system alignment, locating joint centers of rotation, and a solution model to estimate three-dimensional (3-D) digit kinematics. The solution model for each digit was based on assumptions of rigid-body interactions, specific degrees of freedom (DOFs) at each located joint, and the aligned coordinate system definitions. Techniques of inverse kinematics and optimization were applied to calculate the 3-D position and orientation of digit segments during pinching between the thumb and index finger. The 3-D joint center locations were reliably fitted with mean coefficients of variation below 5%. A parameterized form of the solution model yielded feasible solutions that met specified tolerance and convergence criteria for over 85% of the test points. The solution results were intuitive to the pinching function. The thumb was measured to be rotated about the CMC joint to bring it into opposition to the index finger and larger rotational excursions (>10 deg) were observed in flexion/extension compared to abduction/adduction and axial rotation for all joints. While the solution model produced results similar to those computed from a full marker set, the model facilitated the usage of fewer markers, which inherently lessened the effects of passive motion error and reduced the post-experimental effort required for marker processing.
- Published
- 2013
17. Development of a Semi-Active Electromagnetic Vibration Absorber and Its Experimental Study
- Author
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Zhijun Shuai, Ye Wang, Ye Shi, Xueguang Liu, and Xiaoxiao Feng
- Subjects
Test bench ,Engineering ,business.industry ,General Engineering ,Vibration control ,Stiffness ,Structural engineering ,Research Papers ,Finite element method ,Vibration ,Dynamic Vibration Absorber ,Active vibration control ,medicine ,Physics::Atomic and Molecular Clusters ,medicine.symptom ,Physics::Chemical Physics ,business ,Reduction (mathematics) - Abstract
In this work, a semiactive electromagnetic vibration absorber has been developed based on a proposed electromagnetic stiffness adjustable spring model, which presents a new solution for adjusting stiffness in the field of vibration absorber devices. Simulation study on the electromagnetic spring has been performed to determine the structural parameter of the semiactive vibration absorber. An experimental rig is also built up to investigate its practical vibration control effectiveness. Firstly, the finite element model of the test bench is used to analyze its vibration characteristics. Then, the vibration reduction effect is predicted through the simulation analysis, from which the optimal control positions are found. Finally, the experimental studies are also conducted, and the results show that this semiactive electromagnetic vibration absorber has a frequency adjustment range from 21 Hz to 25 Hz, in which considerable vibration reduction from 5 dB to 10 dB can be achieved.
- Published
- 2013
18. Flexing Computational Muscle: Modeling and Simulation of Musculotendon Dynamics
- Author
-
Scott L. Delp, Matthew Millard, Thomas Uchida, and Ajay Seth
- Subjects
Short tendon ,Engineering ,Quantitative Biology::Tissues and Organs ,0206 medical engineering ,Biomedical Engineering ,02 engineering and technology ,Isometric exercise ,Modeling and simulation ,Tendons ,03 medical and health sciences ,0302 clinical medicine ,Physiology (medical) ,Humans ,Computer Simulation ,Simulation ,Muscle force ,business.industry ,Muscles ,Dynamics (mechanics) ,High activation ,Mechanics ,020601 biomedical engineering ,Research Papers ,Elasticity ,Biomechanical Phenomena ,Benchmarking ,Integrator ,Benchmark data ,business ,030217 neurology & neurosurgery - Abstract
Muscle-driven simulations of human and animal motion are widely used to complement physical experiments for studying movement dynamics. Musculotendon models are an essential component of muscle-driven simulations, yet neither the computational speed nor the biological accuracy of the simulated forces has been adequately evaluated. Here we compare the speed and accuracy of three musculotendon models: two with an elastic tendon (an equilibrium model and a damped equilibrium model) and one with a rigid tendon. Our simulation benchmarks demonstrate that the equilibrium and damped equilibrium models produce similar force profiles but have different computational speeds. At low activation, the damped equilibrium model is 29 times faster than the equilibrium model when using an explicit integrator and 3 times faster when using an implicit integrator; at high activation, the two models have similar simulation speeds. In the special case of simulating a muscle with a short tendon, the rigid-tendon model produces forces that match those generated by the elastic-tendon models, but simulates 2–54 times faster when an explicit integrator is used and 6–31 times faster when an implicit integrator is used. The equilibrium, damped equilibrium, and rigid-tendon models reproduce forces generated by maximally-activated biological muscle with mean absolute errors less than 8.9%, 8.9%, and 20.9% of the maximum isometric muscle force, respectively. When compared to forces generated by submaximally-activated biological muscle, the forces produced by the equilibrium, damped equilibrium, and rigid-tendon models have mean absolute errors less than 16.2%, 16.4%, and 18.5%, respectively. To encourage further development of musculotendon models, we provide implementations of each of these models in OpenSim version 3.1 and benchmark data online, enabling others to reproduce our results and test their models of musculotendon dynamics.
- Published
- 2013
19. Mock Circulatory Loop Compliance Chamber Employing a Novel Real-Time Control Process
- Author
-
Charles E. Taylor and Gerald E. Miller
- Subjects
Engineering ,business.industry ,Biomedical Engineering ,Pulsatile flow ,Medicine (miscellaneous) ,Pressure sensor ,Bench test ,Design Innovation Papers ,Reaction ,Real-time Control System ,Deflection (engineering) ,Air space ,Physical design ,business ,Simulation - Abstract
The use of compliance chambers in mock circulatory loop construction is the predominant means of simulating arterial compliance. Utilizing mock circulatory loops as bench test methods for cardiac assist technologies necessitates that they must be capable of reproducing the circulatory conditions that would exist physiologically. Of particular interest is the ability to determine instantaneous compliance of the system, and the ability to change the compliance in real-time. This capability enables continuous battery testing of conditions without stopping the flow to change the compliance chamber settings, and the simulation of dynamic changes in arterial compliance. The method tested involves the use of a compliance chamber utilizing a circular natural latex rubber membrane separating the fluid and air portions of the device. Change in system compliance is affected by the airspace pressure, which creates more reaction force at the membrane to the fluid pressure. A pressure sensor in the fluid portion of the chamber and a displacement sensor monitoring membrane center deflection allow for real-time inputs to the control algorithm. A predefined numerical model correlates the displacement sensor data to the volume displacement of the membrane. The control algorithm involves a tuned π loop maintaining the volume distention of the membrane via regulation of the air space pressure. The proportional integral (PI) controller tuning was achieved by creating a computational model of the compliance chamber using Simulink™ Simscape® toolboxes. These toolboxes were used to construct a model of the hydraulic, mechanical, and pneumatic elements in the physical design. Parameter Estimation™ tools and Design Optimization™ methods were employed to determine unknown physical parameters in the system, and tune the process controller used to maintain the compliance setting. It was found that the resulting control architecture was capable of maintaining compliance along a pressure-volume curve and allowed for changes to the compliance set point curve without stopping the pulsatile flow.
- Published
- 2012
20. Bridging the Gap: Science and Technology Policy in the (Bio)Engineering Classroom.
- Author
-
Kuxhaus L, Michalek AJ, Martin SM, and Steinbacher JL
- Subjects
- Curriculum, Policy, Students, Engineering, Technology
- Abstract
Engineers and scientists have a key role to play in the creation and implementation of government policy. Policymakers need access to the technical expertise that is critical to our national progress and security; however, this need is often overlooked by engineering students, faculty, and professionals. Even though a substantial fraction of scientists and engineers end up pursuing jobs in government, engineering curricula do not usually provide any background in policy and for many, the policy-making process remains a black box. The good news is that there are some simple ways to make it more accessible and to encourage increased involvement. In this paper, we provide a brief overview of the federal policy-making process and present a collection of classroom learning activities that link policy-making and implementation to science and engineering. These can easily be added to existing courses without wholesale curricular changes. We also suggest professional development activities for engineers at all stages of their careers and discuss ways for engineers to become involved in the policy process. Introducing learning and career development activities focused on science and engineering policy will better prepare engineers to provide needed technical expertise to policymakers. It may also encourage engineers to consider careers in local, state, and federal government., (Copyright © 2020 by ASME.)
- Published
- 2020
- Full Text
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21. DYNAMIC SYSTEMS AND CONTROL DIVISION: TECHNICAL DIRECTIONS OVER THE LAST 20 YEARS.
- Author
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AUSLANDER, DAVID M.
- Subjects
PUBLICATIONS ,NANOTECHNOLOGY ,RESEARCH ,MECHANICAL engineering ,TIME delay systems ,UNIVERSITIES & colleges ,ENGINEERING - Abstract
The article focuses on the history of Dynamic Systems and Control Division of American Society Of Mechanical Engineers (ASME). Its periodical "Journal of Dynamic Systems, Measurement, and Control" (JDSMC) has been a research publication. The articles from journal suggested that it dominated the university-based work. Industrial participation has been the top priority in its topics with other areas being nanotechnology, multivehicle control, time-delay systems and automotives. All articles of the journal except the topic of time-delay systems refer to mechanical systems.
- Published
- 2013
- Full Text
- View/download PDF
22. Challenges for the Emerging Decade.
- Author
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Ballal, Dilip
- Subjects
ENGINEERING ,MECHANICAL engineering ,NUCLEAR engineering ,NUCLEAR energy ,GAS turbines ,POWER resources ,GREEN technology - Abstract
The article provides information on the nuclear power engineering research by the Nuclear Engineering Division of the American Society of Mechanical Engineers published in the "Journal of Engineering for Gas Turbines and Power" (JEGTP) in the U.S. In April 2008, the Division selected JEGTP for the publication of the studies relating to gas turbines, energy and power. These papers provide the best technological solutions to define the technology, policy and market issues to achieve a more sustainable energy system.
- Published
- 2009
23. A Mobile Bennett Network Constructed With Identical Square Panels.
- Author
-
Fufu Yang, Yuan Gao, Shuailong Lu, and Kunjing Chen
- Subjects
- *
SQUARE , *KINEMATICS , *PROTOTYPES , *ENGINEERING , *TESSELLATIONS (Mathematics) - Abstract
Mobile networks, constructed with simple linkages by tessellation, have great application potential in engineering as they could change their shapes according to the need of working state by one degree-of-freedom (DOF). However, the existing one-DOF networks are always composed of bar-like links, and cooperated membranes should be designed and fabricated additionally, which makes the design and the realization more complicated. This paper is to construct a one-DOF network of Bennett linkages with identical square panels. Geometric conditions to construct the network are derived by investigating the kinematic compatibility, kinematics is carried out to show the relationships among all Bennett linkages, and the discussion on the design parameter shows the extensibility and the deploying performance, which is validated by two physical prototypes. This work initials the construction of mobile networks with identical polygon-like links, which will simplify the fabrication and realization of deployable structures. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
24. History of the Fluids Engineering Division.
- Author
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Cooper, Paul, Martin, C. Samuel, and O'Hern, Timothy J.
- Subjects
HEAT transfer ,ENGINEERING ,MICROCHANNEL flow ,HYDRAULIC fluids ,WATER hammer ,FLOW meters - Abstract
The 90th Anniversary of the Fluids Engineering Division (FED) of ASME will he celebrated on July 10-14, 2016 in Washington, DC. The venue is ASME’s Summer Heat Transfer Conference (SHTC), Fluids Engineering Division Summer Meeting (FEDSM), and International Conference on Nanochannels and Microchannels (1CNMM). The occasion is an opportune time to celebrate and reflect on the origin of FED and its predecessor—the Hydraulic Division (HYD), which existed from 1926-1963. Therefore, the FED Executive Committee decided that it would be appropriate to publish concurrently a history of the HYD/FED. Accordingly, they commissioned Paul Cooper, C. Samuel Martin, and Timothy O’ Hern to prepare this paper, which would document the division’s past. A brief work in this direction had appeared in the 2010 FED Newsletter (Morgan, W. B., 2010, Brief History of ASME’s HydrauliclFluids Engineering Division, Fluids Engineering Division Newsletter, New York, pp. 6-7), and the research by Martin for the present paper had been under way for several years prior to that (Cooper, P., 2010, “Histoiy of the FED," FED Executive Committee at the ASME-CSME Fluids Engineering Summer Conference (FEDSM-2010), Montreal, OC, Canada, Aug., p. 14). [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
25. Student Activities: Nuclear Engineering Division.
- Subjects
ENGINEERING ,CONFERENCES & conventions - Abstract
The article reports that the organizing committee of ICONE supports financially undergrad and graduate students to attend the conference and to present papers there.
- Published
- 2013
26. High Pressure Turbine Low Radius Radial TOBI Discharge Coefficient Validation Process.
- Author
-
Mirzamoghadam, Alexander V., Riahi, Ardeshir, and Morris, Mark C.
- Subjects
HIGH pressure (Technology) ,TURBINES ,FLUIDS ,FLUID dynamics ,ENGINEERING - Abstract
A TOBI (tangential on board injection), or preswirl, system is a critical component of a high pressure turbine cooling delivery system. Its efficient performance and characterization are critical because the blade and disk life depend on the accuracy of delivering the required flow at the correct temperature and pressure. This paper presents a TOBI flow discharge coefficient validation process applied to a low radius radial configuration starting from a 1 dimensional (1D ) network flow analysis to a 3 dimensional ( 3 D ) frozen rotor computational fluid dynamics (CFD) analysis of the rotor cooling air delivery system. The analysis domain commences in the combustor plenum stationary reference frame, includes the TOBI, transitions to the rotating reference frame as the flow travels through the rotating cover plate orifice, continues up the turbine disk into the slot bottom blade feed cavity, and terminates in the turbine blade. The present effort includes matching a 1D network model with 3D CFD results using simultaneous goal-matching of the pressure predictions throughout the circuit, defining test rig pressure measurements at critical "nondisturbing" locations for quanification of pressure ratio across the TOBI, and finally comparing the TOB1 flow coefficient resulting from stationary cold flow tests with what was obtained from the 3D CFD results. An analysis of the results indicates that the discharge coefficient varies with the pressure ratio and that the traditional method of using a constant discharge coefficient extracted from a cold flow test run under choked conditions leads to overpredicting turbine cooling flows. The TOBI flow coefficient prediction for the present study compares well with the stationary data published by other researchers for the configuration under investigation and the process described in this paper is general for any TOBI configuration [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
27. Flow and Dipole Source Evaluation of a Generic SUV.
- Author
-
Ask, Jonas and Davidson, Lars
- Subjects
AUTOMOBILE windshields & windows ,AUTOMOTIVE engineering ,SPORT utility vehicles ,FINITE volume method ,FLUID dynamics ,ENGINEERING - Abstract
Accurately predicting both average flow quantities and acoustic sources ati the front window of today's ground vehicles are still a considerable challenge to automotive companies worldwide. One of the most important aspects in terms of obtaining not only trus!worthy results but also the most tedious one and therefore perhaps overlooked, is the control and outcome of the mesh generation process. Generating unstructured volume meshes suitable for large eddy simulations with high level representation of geometrical details is both a time consuming and an extremely computer demanding activity. This work investigates two different mesh generation processes with its main aim to evaluate their outcome with respect to the prediction of the two dominating dipole sources in a temporal form of the CurIe `s equation. Only a handful of papers exists that report a high level representation of the vehicle geometry and the aim of predicting the fluctuating exterior noise sources. To the author's knowledge no studies have been conducted in which both these source tenns are evaluated quantitatively against measurements. The current paper investigates the degree to which the amplitude of these two source terms can be predicted by using the traditional law–of–the–wall and hex–dominant meshes with isotropic resolution boxes for a detailed ground vehicle geometry. For this purpose, the unstructured segregated commercial FLUENT finite volume method code is used. The flow field is treated as incompressible and the Smagorinsky–Lilly model is used to compute the subgrid stresses. Mean flow quantities are measured with a 14 hole probe for 14 rakes downstream of the side mirror The dynamic pressure sensors are distributed at 16 different positions over the side window to capture the fluctuating pressure signals. All measurements in this work were conducted at Ford's acoustic wind tunnel in Cologne. All three simulations accurately predict the velocity magnitude closest to the window and downstream of the mirror head recirculation zone. Some variations in the size and shape of this recirculation zone are found between the different meshes, most probably caused by differences in the detachment of the mirror head boundary layer. The Strouhal number of the shortest simulation was computed from the fundamentalfrequency of the drag force coefficient. The computed Strouhal number agrees well with the corresponding results from similar objects and gives an indication of an acceptable simulation time. The dynamic pressure sensors at 16 different locations at the vehicle side window were also used to capture the levels of the two dipole source terms. These results are compared with the three simulations. With the exception of three positions, at least one of the three simulations accurately captures the levels of both source terms up to about 1000 Hz. The three positions with less agreement as compared with measurements were found to be in regions sensitive to small changes in the local flow direction. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
28. Optimum Bifurcating-Tube Tree for Gas Transport.
- Author
-
Tianshu Liu and Katz, Joseph
- Subjects
MASS transfer ,THERMODYNAMICS ,ENGINEERING ,BIFURCATION theory ,DIFFUSION - Abstract
This paper describes optimality principles for the design of an engineering bifurcating-tube tree consisting of the convection and diffusion zones to attain the most effective gas transport. An optimality principle is formulated for the diffusion zone to maximize the total diffusion mass-transfer rate of gas across tube walls under a constant total-volume constraint. This optimality principle produces a new diameter distribution for the diffusion zone in contrast to the classical distribution for the convection zone. In addition, this paper gives a length distribution for an engineering tree based on an optimality principle for minimizing the total weight of the tree under constraints of a finite surface and elastic criteria for structural stability. Furthermore, the optimum branching angles are evaluated based on local optimality principles for a single bifurcating-tube branch. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
29. INF0RMATI0N IN ORDER.
- Author
-
Thilmany, Jean
- Subjects
PRODUCT management ,PRODUCT life cycle ,PRODUCT recall ,MARKETING ,MEDICAL equipment ,ENGINEERING ,MANUFACTURED products - Abstract
The author says that product lifecycle management systems are touted as tools for collaboration, but they are used for much more than that. The marketing and design process moves so quickly, particularly in medical equipment manufacture, that engineers' desks are frequently stacked with papers, nearly all of them design changes. Doron Besser, vice president of marketing and strategy for an Israeli medical-device manufacturer has estimated that his company, based in Herzliya, developed its minimally invasive lung navigation system an estimated 30 percent faster than originally planned, thanks, in great part, to the tracking, organizing, and collaborative PLM software.
- Published
- 2004
- Full Text
- View/download PDF
30. Modeling and Control Analysis of a 3-PUPU Dual Compliant Parallel Manipulator for Micro Positioning and Active Vibration Isolation.
- Author
-
Yun, Y. and Li, Y.
- Subjects
- *
ENGINEERING , *VIBRATION (Mechanics) , *SIGNALS & signaling , *MANIPULATORS (Machinery) , *STIFFNESS (Engineering) - Abstract
In recent years, many applications in precision engineering require a careful isolation of the instrument from the vibration sources by adopting active vibration isolation system to achieve a very low remaining vibration level, especially for the very low frequency under 10 Hz vibration signals. This paper presents a 3-PUPU dual parallel manipulator for both rough positioning and active vibration isolation in a wide-range workspace based on our previous research experiences in the systematical modeling and study of parallel robots. The manipulator is designed as a kind of macro/micro hybrid robot. Both the kinematics model for macro motion and dynamics model for micro motion are established by using stiffness equation and the Kane's method, respectively. An active vibration control strategy is described by using the H2 method. Moreover, numerical simulations on the inverse solution for macro motion, workspace, and the active vibration control effects are performed at the end of this paper. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
31. A New FEM Approach for Simulation of Metal Foam Filled Tubes.
- Author
-
Strano, Matteo
- Subjects
- *
METAL foams , *ENGINEERING , *FINITE element method , *TECHNOLOGY , *MECHANICAL engineering , *STEAM engineering - Abstract
The combination of thin metal cases or tubes with a filling made of metal foams is interesting and promising for many applications, in mechanical engineering. Components made of an outer hollow thin compact metal structure and a cellular lightweight core are especially suited to energy absorption applications. In order to allow for an efficient product/process design with a concurrent engineering approach, reliable and computationally affordable finite element method (FEM) calculations are required by both product and process engineers. The structural performance of these complex composite parts must be numerically predicted, in order to find the optimal combination of outer structure and metal foam properties. While FEM simulation at large deformations of bending, crushing, etc. of thin sheets and tubes is state of the art, the accurate FEM simulation of the mechanical behavior of metal foams cannot be considered fully established. In this paper the three most common methods for FEM simulation of metal foam materials are discussed: (a) homogenization approach, (b) realistic reconstruction of tomographic data, and (c) repetition of standard unit cells. A new effective approach is proposed, suited for simulation of composite, metal foam filled, structures of realistic dimensions. The approach is based on meshing the metal foam by replicating a unit cell made of 32 triangular shell elements, and then by randomizing the nodal position in order to emulate the intrinsic homogeneity of foam morphology. The method is validated by means of different experimental tests. The results show that the proposed method correctly predicts the behavior of foam structures in axial compression. The method slightly overestimated the actual load registered in three point bending tests. Several improvements are described and discussed in the paper, such as randomization of nodal positions of the mesh, in order_ to reduce the overestimation of forces. An FEM approach for the simulation of large deformations of metal foam filled metal structure (e.g., tubes) suited for the design of realistic large dimensions structural components has been presented. The proposed method shows some innovative features with respect to the available scientific literature, such as a configuration based on octahedral unit cells with low number of triangular shell elements. Randomization of nodal positions of each unit cell has been implemented as a method for better representing the intrinsic variability of metal foams and for reducing the stiffness of the simulated structure. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
32. A Simple and Efficient Reformulation of the Classical Manson—Coffin Curve to Predict Lifetime Under Multiaxial Fatigue Loading—Part I: Plain Materials.
- Author
-
Susmel, Luca, Meneghetti, Giovanni, and Atzori, Bruno
- Subjects
- *
CYCLIC loads , *SHEAR (Mechanics) , *STRAINS & stresses (Mechanics) , *TORSION , *STRENGTH of materials , *ENGINEERING - Abstract
This paper summarizes an attempt to devise an engineering method suitable for predicting fatigue lifetime of metallic materials subjected to both proportional and nonproportional multiaxial cyclic loadings. The proposed approach takes as a starting point the assumption that the plane experiencing the maximum shear strain amplitude (the so-called "critical plane") is coincident with the micro-/mesocrack initiation plane. In order to correctly account for the presence of both nonzero mean stresses and nonzero out-of-phase angles, the degree of multiaxiality/nonproportionalily of the stress state damaging crack initiation sites is suggested here to be evaluated in terms of the ratio between maximum normal stress and shear stress amplitude relative to the critical plane. Such a ratio is used then to define nonconventional Manson-Coffin curves, whose calibration is done through two strain-life curves generated under fully reversed uniaxial and fully reversed torsional fatigue loadings, respectively. The accuracy and reliability of our approach were systematically checked by using approximately 350 experimental data taken from the technical literature and generated by testing 13 different materials under both in-phase and out-of-phase loadings. Moreover the accuracy of our criterion in estimating lifetime in the presence of nonzero mean stresses was also investigated. Such an extensive validation exercise allowed us to prove that the fatigue life estimation technique formalized in the present paper is a reliable tool capable of correctly evaluating fatigue damage in engineering materials subjected to multiaxial cyclic loading paths. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
33. Some Analytical Solutions of the Kamal Equation for Isothermal Curing With Applications to Composite Patch Repair.
- Author
-
Tsamasphyros, G. J., Papathanassiou, Th. K., and Markolefas, S. I.
- Subjects
- *
CURING , *DRYING , *DIFFERENTIAL equations , *POLYMERS , *THERMOSETTING composites , *COMPOSITE materials , *CORROSION fatigue of metals , *ADHESIVES , *ENGINEERING - Abstract
In this paper, we derive some analytical solutions of the Kamal cure rate differential equation. The Kamal model is a first order quasilinear ordinary differential equation, describing the progress of the curing reaction of several thermosetting polymers. All the examined cases refer to isothermal curing processes. The solutions obtained in this paper are all of implicit form. The derived solutions are applied to a repair technique based on the adhesive bonding of polymer matrix composite patches onto damaged or corroded areas. Critical duration times of realistic cure cycles corresponding to composite patch repair are estimated. The practical importance of the proposed analytic solutions is demonstrated through the presented engineering application. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
34. Fast Fourier Transform Based Numerical Methods for Elasto-Plastic Contacts of Nominally Flat Surfaces.
- Author
-
Chen, W. Wayne, Shuangbiao Liu, and Wang, Q. Jane
- Subjects
- *
FOURIER analysis , *MODELS & modelmaking , *MATHEMATICAL functions , *OSCILLATIONS , *SURFACE chemistry , *ENGINEERING , *DYNAMICS - Abstract
This paper presents a three-dimensional numerical elasto-plastic model for the contact of nominally fiat surfaces based on the periodic expandability of surface topography. This model is built on two algorithms: the continuous convolution and Fourier transform (CC-FT) and discrete convolution and fast Fourier transform (DC-FFT), modified with duplicated padding. This model considers the effect of asperity interactions and gives a detailed description of subsurface stress and strain fields caused by the contact of elasto-plastic solids with rough surfaces. Formulas of the frequency response functions (FRF) for elastic/plastic stresses and residual displacement are given in this paper. The model is verified by comparing the numerical results to several analytical solutions. The model is utilized to simulate the contacts involving a two-dimensional wavy surface and an engineering rough surface in order to examine its capability of evaluating the elasto-plastic contact behaviors of nominally flat surfaces. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
35. Passive Control of Limit Cycle Oscillations in a Thermoacoustic System Using Asymmetry.
- Author
-
Eisenhower, Bryan, Hagen, Gregory, Banaszuk, Andrzej, and Mezić, Igor
- Subjects
- *
OSCILLATIONS , *HEAT transfer , *ASYMMETRY (Chemistry) , *DYNAMICS , *ENGINEERING , *MECHANICS (Physics) - Abstract
In this paper we investigate oscillations of a dynamical system containing passive dynamics driven by a positive feedback and how spatial characteristics (i.e., symmetry) affect the amplitude and stability of its nominal limit cycling response. The physical motivation of this problem is thermoacoustic dynamics in a gas turbine combustor. The spatial domain is periodic (passive annular acoustics) which are driven by heat released from a combustion process, and with sufficient driving through this nonlinear feedback a limit cycle is produced which is exhibited by a traveling acoustic wave around this annulus. We show that this response can be controlled passively by spatial perturbation in the symmetry of acoustic parameters. We find the critical parameter values that affect this oscillation, study the bifurcation properties, and subsequently use harmonic balance and temporal averaging to characterize periodic solutions and their stability. In all of these cases, we carry a parameter associated with the spatial symmetry of the acoustics and investigate how this symmetry affects the system response. The contribution of this paper is a unique analysis of a particular physical phenomena, as well as illustrating the equivalence of different nonlinear analysis tools for this analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
36. Prediction of Necking in Tubular Hydroforming Using an Extended Stress-Based Forming Limit Curve.
- Author
-
Simha, C. Hari Manoj, Gholipour, Javad, Bardelcik, Alexander, and Worswick, Michael J.
- Subjects
- *
STRESS-strain curves , *SHEET metal work , *ALUMINUM alloys , *STEEL , *STRAINS & stresses (Mechanics) , *ENGINEERING - Abstract
This paper presents an extended stress-based forming limit curve (XSFLC) that can be used to predict the onset of necking in sheet metal loaded under non-proportional load paths, as well as under three-dimensional stress states. The conventional strain-based ϵFLC is transformed into the stress-based FLC advanced by Stoughron (1999, Int. J. Mech. Sci., 42, pp. 1–27). This, in turn, is converted into the XSFLC, which is characterized by the two invariants, mean stress and equivalent stress. Assuming that the stress states at the onset of necking under plane stress loading are equivalent to those under three-dimensional loading, the XSFLC is used in conjunction with finite element computations to predict the onset of necking during tubular hydroforming. Hydroforming of straight and pre-bent tubes of EN-AW 5018 aluminum alloy and DP 600 steel are considered. Experiments carried out with these geometries and alloys are described and modeled using finite element computations. These computations, in conjunction with the XSFLC, allow quantitative predictions of necking pressures; and these predictions are found to agree to within 10% of the experimentally obtained necking pressures. The computations also provide a prediction of final failure location with remarkable accuracy. In some cases, the predictions using the XSFLC show some discrepancies when compared with the experimental results, and this paper addresses potential causes for these discrepancies. Potential improvements to the framework of the XSFLC are also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
37. Theoretical and Experimental Studies for the Application of Shape Memory Alloys in Civil Engineering.
- Author
-
Dolce, Mauro and Cardone, Donatello
- Subjects
- *
SHAPE memory alloys , *ALLOYS , *METALLIC composites , *COMPOSITE construction , *CIVIL engineering , *ENGINEERING - Abstract
Shape memory alloys (SMAs) have great potential for use in the field of civil engineering. The authors of this paper have been involved, from 1996, in several experimental and theoretical studies of the application of SMAs in civil engineering, for national and international research projects. This paper provides an overview of the main results achieved, consisting of the conceptual design, implementation, and testing of three families of SMA-based devices, namely: (i) special braces for framed structures, (ii) seismic isolation devices for buildings and bridges, and (iii) smart ties for arches and vaults. The main advantage of using SMA-based devices in the seismic protection of structures comes from the double-flag shape of their hysteresis loops, which implies three favorable features, i.e., self-centering capability, good energy dissipation capability, and high stiffness at small displacements. The main advantage of smart ties comes from the thermal behavior of SMA superelastic wires, which is opposite to that of steel rod. This implies a strong reduction of the force changes caused by variations of air temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
38. Thermoeconomic Diagnosis: Zooming Strategy Applied to Highly Complex Energy Systems. Part 1: Detection and Localization of Anomalies.
- Author
-
Verda, Vittorio, Serra, Luis, and Valero, Antonio
- Subjects
- *
ENERGY industries , *ENGINEERING , *ENGINEERING systems , *POWER resources , *NATURAL resources , *ENERGY conservation , *COGENERATION of electric power & heat , *ELECTRIC power production - Abstract
This paper presents a summary of our most recent advances in Thermoeconomic Diagnosis, developed during the last three years, and how they can be integrated in a zooming strategy oriented toward the operational diagnosis of complex systems. In fact, this paper can be considered a continuation of the work presented at the International Conference ECOS'99 in which the concepts of malfunction (intrinsic and induced) and dysfunction were analyzed in detail. These concepts greatly facilitate and simplify the analysis, the understanding, and the quantification of how the presence of an anomaly, or malfunction, affects the behavior of the other plant devices and of the whole system. However what remains unresolved is the so-called inverse problem of diagnosing, i.e., given two states of the plant (actual and reference operating conditions), find the causes of deviation of the actual conditions with respect to the reference conditions. The present paper tackles this problem and describes significant advances in addressing how to locate the actual causes of malfunctions, based on the application of procedures for filtering induced effects that hide the real causes of degradation. In this paper a progressive zooming thermoeconomic diagnosis procedure, which allows one to concentrate the analysis in an ever more specific zone is described and applied to a combined cycle. In an accompanying paper the accuracy of the diagnosis results is discussed, depending on choice of the thermoeconomic model. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
39. Close-Loop Cost Equation for Objects Manufactured by Milling.
- Author
-
Kulkarni, Uday A. and Bao, Han P.
- Subjects
- *
MILLING (Metalwork) , *ENGINEERING - Abstract
One of the major drawbacks of present cost estimation models is their incapability of embracing effectively complete product development stage. Parametric estimation works well in early design stage, but when it comes to detail design stage, a more complete estimation is provided by process model based and detail estimation techniques. A major paradigm shift is proposed in this paper whereby "Cost" is to be considered as a design parameter from scientific perspective and it is to be treated as a design consequence rather than as an operational outcome. A comprehensive framework using System Analysis fundamentals is designed to study "Process Cost" aspects of a part or a design. The paper gives detailed implementation of this new approach for objects manufactured largely by milling operation. The paper also suggests a methodology to extend this approach to other manufacturing processes. The proposed Generic Cost Estimation Model shows good agreement with cost estimation by commercial estimation software when applied to the objects manufactured by milling process. It also promises integration of "Cost" with other disciplines in Multidisciplinary Optimization and Collaborative Engineering. The integration is achievable through new information technology interface tools. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
40. Tests and Modeling of a New Vibration Isolation and Suppression Device.
- Author
-
Zhao-Dong Xu, Yeshou Xu, Qianqiu Yang, Chao Xu, Feihong Xu, and Cheng Wang
- Subjects
- *
DYNAMICAL systems , *VIBRATION (Mechanics) , *ENERGY dissipation , *ENGINEERING - Abstract
Vibration is an environmental factor with hazardous effects on the instruments' precision, structural stability, and service life in engineering fields. Many kinds of energy dissipation devices have been invented to reduce the dynamic responses of structures and instruments due to environmental excitations. In this paper, a new kind of vibration isolation and suppression device with high damping performance, fine deformation recoverability, and bearing capacity for platform structures is developed, which is designed by considering the combination of the energy dissipation mechanisms of viscoelastic material, viscous fluid, and air spring. A series of dynamic properties tests on the device are carried out under different excitation frequencies and displacement amplitudes, and a mathematical model considering the coupling effects of energy dissipation of viscoelastic material, viscous liquid, and air spring is proposed. The research results indicate that the vibration isolation and suppression device has high damping capacity, and the proposed mathematical model can well describe the mechanical properties affected by excitation frequency and displacement amplitude. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
41. Experimental and Numerical Study on the Reduction of Residual Stress in the Fillet Weld by Overlay Welding and Cutting Method.
- Author
-
Yun Luo, Wenchun Jiang, Qian Zhang, Yu Wan, Zhang, W. Y., and Wang, Y. J.
- Subjects
RESIDUAL stresses ,WELDING ,ENGINEERING ,FINITE element method ,METALS - Abstract
Fillet weld joint is widely used in engineering structures, but a lot of failures have been generated in the fillet joint affected greatly by weld residual stress, and it is very important to decrease the residual stress. Therefore, this paper proposes a new method using overlay welding and cutting (OWC) to reduce the residual stress in the fillet weld. First, the overlay welding is applied on the root surface of fillet weld, and then the overlaid metal is removed again by cutting. In order to verify this method, a thermal-elasto-plastic analysis method, using finite-element analysis (FEA) techniques, is developed to evaluate the residual stress change during the process of OWC. The impact indention measurement is also used to measure the surface residual stress. The results of FEA were compared with experimental data to confirm the accuracy of the developed finite-element method (FEM). In order to provide a guideline for design, the dimension effects including overlay weld width and height on residual stress have been investigated. It finds that OWC can decrease 25-40% of the as-weld residual stress, and increasing the overlay width and height is helpful to decrease the residual stress, which provides a reference for the reduction of residual stress in the fillet weld. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
42. Verification of the Linear Matching Method for Limit and Shakedown Analysis by Comparison With Experiments.
- Author
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Ure, James, Haofeng Chen, and Tipping, David
- Subjects
ACCURACY ,ENGINEERING ,CUTTING (Materials) ,NOZZLES ,FINITE element method - Abstract
The linear matching method (LMM), a direct numerical method for determining shakedown and ratchet limits of components, has seen significant development in recent years. Previous verifications of these developments against cyclic nonlinear finite element analysis (FEA) have shown favorable results, and now this verification process is being extended to include comparisons with experimental results. This paper presents a comparison of LMM analysis with experimental tests for limit loads and shakedown limits available in the literature. The limit load and shakedown limits were determined for pipe intersections and nozzle-sphere intersections, respectively, thus testing the accuracy of the LMM when analyzing real plant components. Details of the component geometries, materials and test procedures used in the experiments are given. Following this a description of the LMM analysis is given which includes a description of how these features have been interpreted for numerical analysis. A comparison of the results shows that the LMM is capable of predicting accurate yet conservative limit loads and shakedown limits. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
43. Chirality Induced by Structural Transformation in a Tensegrity: Theory and Experiment.
- Author
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Li-Yuan Zhang, Zi-Long Zhao, Qing-Dong Zhang, and Xi-Qiao Feng
- Subjects
- *
CHIRALITY , *TENSEGRITY (Engineering) , *TENSILE strength , *ENGINEERING , *STRUCTURAL engineering - Abstract
Chiral structures have many technologically significant applications in engineering. In this paper, we investigate, both theoretically and experimentally, the structural transformation from a symmetric X-shaped tensegrity to a chiral structure under uniaxial tension. When the applied tensile force exceeds a critical value, the initially achiral structure would exhibit snap-through buckling. At the critical state, the in-plane deformation mode of the tensegrity switches into an off-plane one. The critical condition of the structural transformation is provided in terms of structural parameters. An experiment was performed to validate the theoretical model. This work may not only deepen our understanding of the stability of tensegrities but also help design chiral structures for engineering applications. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
44. Failure Mode and Fatigue Behavior of Dissimilar Friction Stir Spot Welds in Lap-Shear Specimens of Transformation-Induced Plasticity Steel and Hot-Stamped Boron Steel Sheets.
- Author
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Hong, S. H., Sung, S.-J., and Pan, J.
- Subjects
- *
FRICTION stir welding , *FATIGUE life , *BORON steel , *MANUFACTURING processes , *ENGINEERING - Abstract
Failure mode and fatigue behavior of dissimilar friction stir spot welds in lap-shear specimens of transformation-induced plasticity steel (TRIP780) and hot-stamped boron steel (HSBS) sheets are examined in this paper. Optical micrographs of the dissimilar TRIP780IHSBS friction stir spot welds made by a concave silicon nitride tool before and after testing are obtained and examined. These micrographs indicate that subject to quasi-static and cyclic loading conditions, the TRIP780/HSBS welds fail from cracks growing through the TRIP780 sheets where the tool was plunged into and the thickness was reduced. The bending moments and the transverse shear force near the welds are derived with consideration of the load offset, the weld gap, and the bend distance for calculation of analytical global stress intensity factor solutions for the welds in lap-shear specimens. A fatigue model of kinked crack growth is used to estimate fatigue lives based on the local stress intensity factor solutions for kinked cracks. The estimated fatigue lives with consideration of the weld gap and the bend distance are in agreement with the fatigue test results under low-cycle loading conditions and lower than the fatigue test results under high-cycle loading conditions. The estimated fatigue lives suggest that the weld gap and the bend distance can significantly affect fatigue lives of the friction stir spot welds in lap-shear specimens under cyclic loading conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
45. Influence of Kinematics During Roller Clinching on Joint Properties.
- Author
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Weiss, Maria and Volk, Wolfram
- Subjects
- *
SHEET metal , *JOINING processes , *KINEMATICS , *MANUFACTURING processes , *ENGINEERING - Abstract
Roller clinching is an effective way to join continuous sheet metal components. In contrast to translational clinching, joining with rotational tool movement is a continuous process in which the semifinished parts can be fed through the joining device at a constant high velocity without stopping and accelerating. Because of the special kinematics, which differs from translational clinching, the clinchpoint reveals an asymmetric joint formation. This paper deals with the influence of different rolling radii of the tools and stripping forces on the clinchpoint formation and the resulting mechanical joint properties. Experiments are performed to determine tensile and shear strengths of the rotational clinchpoints. They are compared to the properties of translational clinchpoints. Furthermore, the kinematic mechanisms during roller clinching influencing the clinchpoint geometiy are identified. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
46. Unified Solution of Burst Pressure for Defect-Free Thin Walled Elbows.
- Author
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Li, Y., Zhao, J. H., Zhu, Q., and Cao, X. Y.
- Subjects
PRESSURE gages ,THERMODYNAMIC state variables ,TENSILE tests ,CUTTING (Materials) ,ENGINEERING - Abstract
In order to study the mechanical properties of defect-free thin walled elbows (TWE), and evaluate impacts of the intermediate principal stress effect, tension/compression ratio, and strain-hardening of materials into logical consideration, this research, in the framework of finite deformation theory, derived the computational formula of burst pressure for defect-free TWE according to unified strength theory (UST). In addition, influences of various factors on burst pressure were analyzed, which include strength disparity (SD) effect of materials, intermediate principal stress, curvature influence coefficient, strain-hardening exponent, yield to tensile (Y/T) and thickness/radius ratio. The results show that the greater the tension/compression ratio is, the higher the burst pressure is. The influence of the SD effect of materials is more obvious with the increase of elbow curvature and intermediate principal stress. The intermediate principal stress effect can bring the self-bearing capacities and strength potential of materials into a full play, which can achieve certain economic benefits for projects. Moreover, the burst pressure of defect-free TWE increases with the growth of yield ratio and thickness/radius ratio, while decreases with the rise of curvature influence coefficient and strain-hardening exponent. It is also concluded that the Tresca-based and Mohr-Coulomb-based solutions of TWE are the lower bounds of the burst pressure, the twin shear stress (TSS)-based solution is the upper bound of the burst pressure, and the solutions based on the other yield criteria are between the above two. The unified solution in this paper is suitable for all kinds of isotropous materials which have the SD effect and intermediate principal stress effect. As the deduced formula has unified various burst pressure expressions proposed on the basis of different yield criteria for elbows of any curvature (including straight pipelines), and has established the quantitative relationships among them, its applicability is broader. Therefore, the unified solution is of great significance in security design and integrity assessment of defect-free TWE. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
47. Experimental and analytical characterization of alternative aviation fuel sprays under realistic operating conditions
- Author
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N. K. Rizk, Wajid A. Chishty, and Andrew Corber
- Subjects
Materials science ,Aviation ,020209 energy ,Nuclear engineering ,Nozzle ,diffraction ,Energy Engineering and Power Technology ,Aerospace Engineering ,02 engineering and technology ,engineering.material ,Jet fuel ,Combustion ,01 natural sciences ,010305 fluids & plasmas ,0203 mechanical engineering ,0103 physical sciences ,fuels ,0202 electrical engineering, electronic engineering, information engineering ,Calibration ,ejectors ,Aviation fuel ,sprays ,drops ,020301 aerospace & aeronautics ,business.industry ,Mechanical Engineering ,Fuel injection ,Fuel Technology ,Nuclear Energy and Engineering ,aviation ,engineering ,flow (Dynamics) ,Combustion chamber ,business ,fluids ,lasers - Abstract
The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities., ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, Monday 11 June 2018, Oslo, Norway
- Published
- 2019
48. The Creative Impulse.
- Author
-
Brown, Alan S.
- Subjects
CREATIVE ability in technology ,TECHNOLOGICAL innovations ,ENGINEERING ,CORPORATE growth ,INDUSTRIAL research ,INDUSTRIAL management ,TECHNOLOGY ,SCIENTIFIC literature - Abstract
The article analyzes the benefits of creative ability and technological innovations in today's world. According to an industry expert, today's corporate growth is powered by innovation. The use of creative exercises for business rather than engineering had been around since the 1920s. According to Graham Thompson, the former head of the University of Manchester's School of Mechanical, Aerospace, and Civil Engineering in Great Britain, there is a whole literature of articles and learned papers on creativity, especially on the management side, going back to the 1920s. It is only been during the past 10 to 15 years that the engineering community has woken up to these techniques.
- Published
- 2007
- Full Text
- View/download PDF
49. A Review of Engineering Research in Sustainable Manufacturing.
- Author
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Haapala, Karl R., Fu Zhao, Camelio, Jaime, Sutherland, John W., Skerlos, Steven J., Dornfeld, David A., Jawahir, I. S., Clarens, Andres F., and Rickli, Jeremy L.
- Subjects
- *
ENGINEERING , *MANUFACTURING processes , *INDUSTRIAL research , *SUSTAINABILITY , *RESEARCH & development - Abstract
Sustainable manufacturing requires simultaneous consideration of economic, environmental, and social implications associated with the production and delivery of goods. Fundamentally, sustainable manufacturing relies on descriptive metrics, advanced decision-making, and public policy for implementation, evaluation, and feedback. In this paper, recent research into concepts, methods, and tools for sustainable manufacturing is explored. At the manufacturing process level, engineering research has addressed issues related to planning, development, analysis, and improvement of processes. At a manufacturing systems level, engineering research has addressed challenges relating to facility operation, production planning and scheduling, and supply chain design. Though economically vital, manufacturing processes and systems have retained the negative image of being inefficient, polluting, and dangerous. Industrial and academic researchers are re-imagining manufacturing as a source of innovation to meet society's future needs by undertaking strategic activities focused on sustainable processes and systems. Despite recent developments in decision making and process- and systems-level research, many challenges and opportunities remain. Several of these challenges relevant to manufacturing process and system research, development, implementation, and education are highlighted. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
50. Mixing Enhancement by Microrotor in Step Channel.
- Author
-
Dinh, Thien X. and Ogami, Yoshitumi
- Subjects
MICROFLUIDICS ,MIXING machinery ,ROTORS ,MICROFLUIDIC devices ,MICROFLUIDIC analytical techniques ,ENGINEERING ,MICROCHEMISTRY - Abstract
In this paper, the mixing enhancement of a micromixer consisting of a step channel and a shuttlecock rotor suspended in the step is numerically analyzed. Asymptotic mixing performance is investigated as a function of Strouhal and Peclet numbers by particle tracking simulation and the Eulerian approach. The simulation results show that the rotor creates downward and inward flows in behind the rotor paddles, whereas the upward and outward flows are produced in front of the rotor paddles. At a small Strouhal number, convective mixing is very poor. However, the mixing direction is rotated by 90 deg, which can reduce the mixing time by the square of the aspect ratio of the cross section of the channel. In contrast, at a relatively large Strouhal number, good convective mixing occurs. Quantitative analysis of mixing performance of the mixer demonstrates that the mixing structures are similar for the same Strouhal number and mixing is improved with increasing Strouhal number. The mixing efficiency of the mixer decreases linearly with increasing log of the Peclet number at a relatively large Strouhal number. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
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