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The lack of a process and an instrument to serve as a tool to control the technical condition and maintenance of land removal equipment in material handling is an acute social and industrial problem. Hence, the definition of these tools is an essential factor of safe operation in the mining, oil, and construction industry, as major sources for the development of a country. Therefore, the results of this investigation are presented based on the objectives pursued by the design, validation, and analysis of the reliability of a process and instrument for visual inspection of mechanical components for land removal equipment, which constitutes an adequate and efficient tool for inspectors, operators, and maintenance team in need to evaluate tolerable imperfections and defects. To validate the results obtained, the Delphi method was applied and the agreement between experts was assessed using Kendall’s coefficient. Moreover, the factorial analysis for principal components was carried out to assess construct validity. Thus, it is concluded that the tool represents a source of technical information that supports the decision-making considering operation and maintenance parameters evidenced in the inspection critical routes.

Here we demonstrate nano-scale liposome templating using dielectrophoretic (DEP) force. When an AC electric field is applied between two parallel electrodes, the resulting DEP force will trap and physically confine the targets, allowing for dynamic manipulation without the need for mechanical components or hydrodynamic force. Moreover, due to the frequency dependence of the DEP effect, the physical confinement is adjustable and can be reversed by tuning the frequency. We believe that this approach will be useful for single Extracellular Vesicle confinement and analysis.

Optimization means the demonstration of detecting the optimal outcome under specific circumstances. Engineers need to take numerously specialized as well as supervisory decisions in various design phases, construction, and industrial system maintenance. The main target of every such decision is either to restrain the work necessitated or raise the profit. As the profit wanted or the work required in any situation of real world can be expressed as a specific decision variable’s function, optimization can be characterized as the way towards discovering the conditions that provide maximum or minimum function values. Complex problems of optimization while solving with traditional numerical methods had mathematical downsides. This is the reason because of which researchers had to be dependent on meta-heuristic techniques. Meta-heuristics have turned out to be amazingly usual due to its local optima avoidance, simplicity and flexibility characteristics. IGWO is a new meta-heuristic inspired by grey wolves. In this paper, the implementation of improved grey wolf optimization is done for the optimization of pressure vessel design and welded beam design that have various salient engineering applications. The comparison of achieved results with some other approaches reveals the efficacy of IGWO algorithm to solve these significant mechanical engineering design optimization problems.

Most of the mechanical components manufactured in rubber materials experience fluctuating loads, which cause material fatigue, significantly reducing their life. Different models have been used to approach this problem. However, most of them just provide life prediction only valid for each of the specific studied material and type of specimen used for the experimental testing. This work focuses on the development of a new generalized model of multiaxial fatigue for rubber materials, introducing a multiparameter variable to improve fatigue life prediction by considering simultaneously relevant information concerning stresses, strains, and strain energies. The model is verified through its correlation with several published fatigue tests for different rubber materials. The proposed model has been compared with more than 20 different parameters used in the specialized literature, calculating the value of the R2 coefficient by comparing the predicted values of every model, with the experimental ones. The obtained results show a significant improvement in the fatigue life prediction. The proposed model does not aim to be a universal and definitive approach for elastomer fatigue, but it provides a reliable general tool that can be used for processing data obtained from experimental tests carried out under different conditions.

Artificial intelligence is changing perspectives of industries about manufacturing of components, introducing emerging techniques such as additive manufacturing technologies. These techniques can be exploited to manufacture not only precision mechanical components, but also interfaces. In this context, we investigate the use of artificial intelligence and in particular genetic algorithms to identify optimal multi-scale roughness features to design prototype surfaces achieving a target contact mechanics response. Exploiting an analogy with biology, the features of roughness at a given length scale are described through model profiles named chromosomes. In the present work, the mathematical description of chromosomes is firstly provided, then three genetic algorithms are proposed to superimpose and combine them in order to identify optimal roughness features. The three methods are compared, discussing the topological and spectral features of roughness obtained in each case.

As the world develops, new and more advanced ways of transportation are invented; i.e. drones. Drones are used in several applications. However, the drone market does not utilize the need of medical emergency drones today, where these drones can be used to save countless lives in severe cases, e.g. sudden cardiac arrest. In case of cardiac arrest, defibrillators may save the life if it reaches the victims within short time. It raises the survival rate exponentially. Nonetheless, reaching the victims in a short period of time is challenging as the weight of the equipment is large. This work aims to design an autonomous drone that will be able to carry heavy payloads (portable medical equipment) while being fast and agile. The medical equipment/components are studied to choose the most fit for the proposed design in terms of efficiency and weight. The drone’s components are compared and studied in detail, allowing to choose the fittest motors, ESCs, frame, battery, and propellers. After which the quadcopter’s ability is expected to successfully achieve the objective of trying to save victim life in the city of Sharjah. In addition, the work includes a SolidWorks analysis to the design of the drone’s mechanical components to estimate the possibility of failure.

This letter presents SecPump, a new open-source wireless infusion pump platform dedicated to security researchers. The novelty of the platform is that it is “plug and play.” Indeed, SecPump simulates a functional infusion pump system on a single board without requiring additional hardware or mechanical components. The presented cyber-physical platform intends to provide a framework for security evaluation, tailored for countermeasure development against security flaws related to medical devices. This letter presents the functionality of the cyber-physical device, its wireless features, and its portability across several hardware architectures. Finally, both hardware and software attacks are showcased on the platform.

The pulmonary blood-gas barrier represents a remarkable feat of engineering. It achieves the exquisite thinness needed for gas exchange by diffusion, the strength to withstand the stresses and strains of repetitive and changing ventilation, and the ability to actively maintain itself under varied demands. Understanding the design principles of this barrier is essential to understanding a variety of lung diseases, and to successfully regenerating or artificially recapitulating the barrier ex vivo. Many classical studies helped to elucidate the unique structure and morphology of the mammalian blood-gas barrier, and ongoing investigations have helped to refine these descriptions and to understand the biological aspects of blood-gas barrier function and regulation. This article reviews the key features of the blood-gas barrier that enable achievement of the necessary design criteria and describes the mechanical environment to which the barrier is exposed. It then focuses on the biological and mechanical components of the barrier that preserve integrity during homeostasis, but which may be compromised in certain pathophysiological states, leading to disease. Finally, this article summarizes recent key advances in efforts to engineer the blood-gas barrier ex vivo, using the platforms of lung-on-a-chip and tissue-engineered whole lungs. © 2020 American Physiological Society. Compr Physiol 10:415-452, 2020.

Development of an advanced electromechanical system requires a blend of technical expertise and knowledge, from electrical and mechanical engineering to software and system engineering. Engineers working in this field must be able to understand and analyze the interrelated electrical and mechanical components, as well as computer controlling programs, to communicate with each system part. In this paper, we aim to review the requirements and technical knowledge for development of these new technologies.

In powder metallurgy the addition of alloying elements is a widely used alternative to increase the service life of mechanical components. However, they have an associated cost. One less exploited process is surface enrichment (or surface alloying), whose same result is obtained on the surface, but at a much lower cost. Self-lubricating composites are especially complex to be enriched, precisely because they have to avoid the deposition of alloying elements over the lubricant stocks. This paper reports the characterization and tribological properties of self-lubricating composites enriched with molybdenum or nickel. Sintered samples were produced for comparative purposes. Wear resistance, friction coefficient and wear rate were analyzed for the evaluation of tribological properties. The results showed that the enrichment process did not cover the lubricant stocks. In addition, the Mo-enriched samples presented the best tribological results, with a 250 % increase in scuffing resistance in relation the sintered sample, and lower wear rate.

The development of systems for the deterministic transfer of two-dimensional (2D) materials have undoubtedly contributed to a great advance in the 2D materials research. In fact, they have made it possible to fabricate van der Waals heterostructures and 2D materials-based devices with complex architectures. Nonetheless, as far as we know, the amount of papers in the literature providing enough details to reproduce these systems by other research groups is very scarce in the literature. Moreover, these systems typically require the use of expensive optical and mechanical components hampering their applicability in research groups with low budget. Here we demonstrate how a deterministic placement system for 2D materials set up with full capabilities can be implemented under 900 Eur which can be easily implemented in low budget labs and educational labs., 4 Figures in main text, a full step-by-step assembly guide in the supp. info. all part numbers needed to assemble the setup included

Mechanical peak power output (PPO) is a determinant of performance in sprint cycling. The purpose of this study was to examine the relationship between PPO and putative physiological determinants of PPO in elite cyclists, and to compare sprint performance between elite sprint and endurance cyclists. Thirty‐five elite cyclists (18 endurance; 17 sprint) performed duplicate sprint cycling laboratory tests to establish PPO and its mechanical components. Quadriceps femoris (QVOL) and hamstring muscle volume (HAMVOL) were assessed with MRI, vastus lateralis pennation angle (PθVL) and fascicle length (FLVL) were determined with ultrasound imaging, and neuromuscular activation of three muscles was assessed using EMG at PPO during sprint cycling. For the whole cohort, there was a wide variability in PPO (range 775‐2025 W) with very large, positive, bivariate relationships between PPO and QVOL (r = .87), HAMVOL (r = .71), and PθVL (r = .81). Step‐wise multiple regression analysis revealed that 87% of the variability in PPO between cyclists was explained by two variables QVOL (76%) and PθVL (11%). The sprint cyclists had greater PPO (+61%; P < .001 vs endurance), larger QVOL (P < .001), and BFVOL (P < .001) as well as more pennate vastus lateralis muscles (P < .001). These findings emphasize the importance of quadriceps muscle morphology for sprint cycling events.

The type of locomotion achieved by reptilian organisms such as snakes is a truly fascinating phenomenon. Replicating the serpentine movement is a difficult task, but once such it is replicated to some degree, it could be used to make robots which have a large scope of application in many different fields. Replication of this type of motion makes it easier to access constricted areas in search and rescue operations carried out by response teams during, say, natural disasters. Also, if such movement can be replicated in an appropriately sized robot, it can be used in surveillance applications too. Serpentine motion, when properly replicated, can also open up new avenues for robots that are used to navigated clustered terrain. This paper represents a progress report on the research about different ways of achieving serpentine motion in robots using electromechanical and mechanical components. The robot shown in this paper was synthesized, and it was able to achieve serpentine and sidewinding motions.

Nanosecond pulsed laser texturing has been performed on stainless steel with the objective of developing surface treatments to reduce bacterial adhesion on mechanical components in food handling machinery. The adhesion of Escherichia coli (E. coli) on four distinct textures has been investigated with standardised protocols for measurement of antibacterial performance. Surface morphology has been studied in detail for each texture to ascertain the presence of hierarchical structures and determine the role of topography in reducing bacterial adhesion. Despite the absence of sub-micrometric features comparable with bacterial size, this work highlights the crucial role that nanosecond pulsed laser irradiation plays in promoting a thin layer of iron oxide that reduces E. coli adhesion through local repulsive electrostatic interactions.

In this chapter, building process of the robot prototype is presented, which involved manufacturing and integration of mechanical components, electrical parts and electronic control systems. Implementation of low-level and high-level software was a part of the integration. Numerous laboratory experiments of the prototype were conducted that prove that the dissertation thesis is satisfied. Finally, an enhanced version of the robot prototype was presented with focus on control system and electronic components. The prototype was tested in different work environments and the enhanced pipeline robotic system was prepared for industrial applications.

Additive manufacturing is an emerging technique that is not only subjected to the interest of academic world because of its peculiar characteristics to obtain new material properties and optimized 3D geometries, but it also finds the interest of the industrial sector because of the possibility to build advanced components never realized until now. Among the additive manufacturing processes, Laser Powder Bed Fusion process is perhaps the most used in producing components out of metallic materials. In particular, thanks to its low density and its hypoeutectic favourable composition, AlSi10Mg alloy is particular suitable for the production of lightweight components by additive manufacturing. However, for safety reasons, their mechanical, static and cyclic, characteristics need to be well understood and predicted. Unfortunately, they are dramatically influenced by process parameters that in turn may promote killer defects dangerous for the fatigue strength of load bearing mechanical components. This contribution is aimed at highlighting the influence of defects on the fatigue resistance of AlSi10Mg samples produced by laser powder bed fusion. The combination of process parameters were obtained that maximizes the fatigue strength and reduces the scattering of the results.

Precision coatings applied to mechanical components do not only provide different degrees of protection of their surfaces but can also contribute to significant improvement of performance. Given this fact, this chapter presents the main coating technologies and their practical applications. Beginning with the presentation of the main functions and types of coatings, the chapter progresses by offering information regarding the methods, the area of application, and the performance properties for each of the presented coating technologies. Furthermore, the quality and precision aspects, as well as the applicable standards, are discussed. Some practical examples regarding the performance improvement of different mechanical components by applying precision coatings are additionally presented. The final goal of this chapter is to enable the readers to choose the proper system for their application, by providing all the relevant information regarding various coating types.

Friction between moving bodies in mutual contact is a field studied in depth. A strategy to improve the tribological performance of mechanical components consists of modifying the surface microstru...

In the mechanical design, the selection among material alternatives has become a pressing issue due to the progressive growth in the complexity of mechanical systems, in search of continuous increase in performance and the presence of a wide range of possible materials. Moreover, there are many requests for projects, and this makes the choice of material a decisive activity for the success or failure of the project itself. This paper makes a comparative evaluation of two important approaches to identify the best materials alternatives: The C-VIKOR and the Fuzzy Axiomatic Design. The work considers as a case study the selection of the material for the production of the valve seats in a high-performance engine. An evaluation of the results obtained is made to show the peculiarity of each of the two approaches.

Since the early 1900’s, the time when IPT acquired its first optical microscope for metallography, failure analysis has been a duty whose accomplishments have never stopped. The term “failure analysis” has a broad meaning, but the intent now is to restrict this meaning to the analyses performed on fractured or cracked mechanical components and structures intended to determine their causes. Cases related to loss of stability of structures due to deformation, wear and general corrosion that are also considered failures will not be treated in this article. Engineers normally try to design machines, engines and all sorts of mechanical components and structures to be failure proof. For that material selection, manufacturing processes, assembling and maintenance recommendations are carefully specified. The appliance to these specifications normally prevents failures. However, if one or more of the items specified above is not obeyed, the probability of failure increases. Furthermore, there are situations in which, even though all the specifications are followed by the book, a part may fail and an accident ensue. Some selected failure analysis performed by IPT are presented in this paper. The trends for the future are to apply monitoring techniques to mechanical components and structures, capable of alerting possible failures before they occur . Keywords : failure; fracture; fatigue; overloading, liquid/gas equilibrium, hydraulic block.

The design of modern mechanical components often requires the use of low-density and high-strength parts. Additive manufacturing presents competence in obtaining format complexity internally (voids, ducts, channels) and externally (shape, holes). However, parts obtained by material extrusion additive manufacturing are highly anisotropic and relatively weak. This paper aims to present a new mechanical design technique that combines the high geometry flexibility of additive manufacturing with internal structuring reinforcement by high-strength materials, which enables optimized parts with reinforcement in the most mechanical stressed areas during service, through adopting structured internal geometry filled with reinforcement material. Dense test specimens and test specimens with internal structural canals filled with reinforcement material (epoxy resin and carbon fibers) were designed, fabricated and tested physically and virtually. The obtained results provide property values for 3D-printed acrylonitrile butadiene styrene (typical material of additive manufacturing) and for this polymer reinforced with various reinforcement material configurations (useful for mechanical design). The reinforcement decreased anisotropy and improved mechanical properties. Optimized parts filled with resin and long carbon fibers had maximum flexural resistance of 112 MPa, with a specific weight of 1.1 g/cm3. This reinforcement provided parts with specific flexural strength similar to structural aluminum alloys, preserving the geometry and external dimension of the printed parts. The technique presented here shows the possibility of new conceptions in mechanical components design and strength optimization by internal reinforcement canals in parts. The technique is useful for mechanical design activity and allows for new product conceptions based on additive manufacturing.

Safety is important in rehabilitation assist suits. To address this issue, we have developed a velocity-based mechanical safety device (VBMSD) for an assist suit to aid flexion and extension of a patient’s knee joint. The VBMSD turns off the assist suit’s motor when the knee joint angular velocity generated by the motor is equal to or higher than a preset threshold level. The name for this level is the “detection velocity level (DVL).” The DVL is adjustable according to the requirement of each patient’s gait exercise. In addition, the VBMSD works even when the assist suit’s computer has broken down, because it consists of only passive mechanical components such as springs. However, not only safety, but portability is also important in the assist suit because patients wear it. Therefore, the VBMSD attached to it is also required to be as small and light as possible. In this paper, we introduce a new compact velocity-based mechanical safety device (compact VBMSD) designed in this study. Comparing the previous VBMSD and the compact VBMSD, we describe how much smaller and lighter the compact VBMSD is. Furthermore, we check that the compact VBMSD does not theoretically resonate with a walking cycle (0-IHz) in their gait exercise. Finally, in order for many patients to use it, we confirm that the DVL in the compact VBMSD is adjustable up to the kneejoint angular velocity of 6 rad/s, which is the velocity level of healthy adults’ walking.

The failure of moving mechanical components is often accompanied by hydrogen embrittlement caused by hydrogen diffusion in steel. One considerable mechanism for hydrogen diffusion is its ingress from lubricant decomposition. We investigated quantitatively the ingress of hydrogen generated by lubricant decomposition into bearing steels using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Deuterated lubricants were used to discriminate between the original hydrogen in steel and the hydrogen generated from lubricant decomposition. The highest concentration of deuterium was always near the raceway surface, and the concentration decreased gradually as the depth was increased. The diffused deuterium increased in a parabolic relation with the duration of friction. To protect steels against the ingress of hydrogen, we studied the effect of a diamond-like carbon (DLC) coating, which has a low diffusion coefficient of hydrogen. DLC reduced but did not completely prevent the ingress of hydrogen, which resulted from the reduction in the amount of hydrogen generated from the tribochemical and thermal decomposition of lubricants.

The life prediction of mechanical components in presence of Thermo-Mechanical Fatigue (TMF) is a crucial issue of the design activity. In the combustion engine, that action looks rather difficult because of a superposition of several damage phenomena. Some TMF models are currently available in the literature, but they include many parameters, whose calibration usually requires an onerous testing activity. Therefore, industry requires an assessment of those techniques, to be implemented through some simplified and reliable procedures. In this paper, the prediction of TMF life of a lightweight engine component is based on a new procedure, exploiting the isothermal Low-Cycle Fatigue (LCF) and creep tests, some theoretical approaches applied to TMF and numerical modeling. The A356 Aluminum Alloy is analyzed, as an example of strategic material used to design the new automotive lightweight engines. The calibration of TMF models based on the isothermal LCF and creep tests was found reliable. The fatigue life prediction looks compatible with some preliminary experimental results. Therefore, the proposed approach is suitable to simplify the design procedure, to decrease costs, especially related to testing, and to perform a preliminary trade-off activity of the engine layout.

The chapter presents a framework for establishing human-robot collaborative assembly in industrial environments. To achieve this, the chapter first reviews the subject state of the art and then addresses the challenges facing researchers. The chapter provides two examples of human-robot collaboration. The first is a scenario where a human is remotely connected to an industrial robot, and the second is where a human collaborates locally with a robot on a shop floor. The chapter focuses on the human-robot collaborative assembly of mechanical components, both on-site and remotely. It also addresses sustainability issues from the societal perspective. The main research objective is to develop safe and operator-friendly solutions for human-robot collaborative assembly within a dynamic factory environment. The presented framework is evaluated using defined scenarios of distant and local assembly operations when the experimental results show that the approach is capable of effectively performing human-robot collaborative assembly tasks.

The industrial progress has reached a level in which it is necessary to understand the behavior of mechanical components and to monitor their conditions without disassembling them. Nowadays, a suitable methodology is based on vibrational analysis usually performed through acceleration signals measured directly on the system to be tested. However, in the last years, the industrial scenario has deeply changed due to the need for time reduction, in particular, for the control operations at the end of the productive line. The genuine methods based on acceleration measurements, for example, through piezoelectric accelerometers, came into conflict with the industrial need as the sensors used for the quality control have to be easily and fastly mounted and unmounted. A valid alternative is represented by the exploitation of laser triangulation sensors that are able to measure the dynamic displacement in a contactless way, strongly reducing the (un)mounting time. The target of this paper is to highlight pros and cons of the contactless displacement analysis through laser triangulation sensors with respect to the contact one through genuine accelerometers by means of a comparison between the results obtained both for experimental modal analysis and vibrational diagnostics of rotating machines.

This chapter presents a mechatronic system concept for highly productive and accurate machine tools. Using the example of an experimental machine called ‘MAX’, it will be demonstrated that the working precision of a machine can be increased whilst the effort required for machining and assembly of its mechanical components is kept to a minimum. Firstly, a novel machine structure is introduced, which allows a high reproducibility with low manufacturing effort and provides the necessary degrees of freedom for the correction of motion deviations as well as the additional actuators required for the compensation of dynamic excitations. The simplified requirements for production and assembly of the machine presented leads inevitably to large geometric and kinematic errors. These errors are modelled using rigid-body kinematics. Circularity tests and angular measurements are performed to verify the machine’s ability to correct its geometric-kinematic deviations. For a highly dynamic engraving process, the reduction of the dynamic excitation caused by the drive reaction forces is demonstrated using the principle of impulse compensation. Finally, an approach to the correction of elastic and thermo-elastic errors and the comprehensive modelling and simulation-based analysis of the experimental machine are outlined.

As the number of elevators increases, some parts of the elevator tractor are not in place, which leads to the occurrence of elevator accidents. The safety of elevator tractor is very urgent. In the process of elevator operation, due to frequent use, friction and impact between mechanical components intensified, resulting in unnecessary loads leading to vibration, thus reducing the stability and safety of elevator tractor, shortening the service life of elevator tractor and existing security risks. Faced with serious elevator safety problems, it is necessary to design an elevator detection system for common mechanical faults of elevator tractor. This system can display the waveform of the current tractor vibration signal in real time to detect the elevator operation status data. The staff can judge the current safety situation according to the elevator parameters stipulated by relevant regulations, and can provide special inspection and maintenance personnel with certain information support.

The use of fracture mechanics based methodologies to assess the influence of defects on the high cycle fatigue resistance of mechanical components has become increasingly important for industrial applications and design. This presentation introduces the most commonly used fracture mechanics methods, emphasizing the assumptions on which they are based and analyzing their potential in predicting the influence of the main geometrical, mechanical and microstructural variables involved in the definition of the fatigue resistance of the components. Underlying hypotheses are discussed thoroughly and possible directions for future research are suggested. Applications examples on different configurations with small defects are presented. Finally, the potential of the fracture mechanics methodologies is analyzed when proposing simplifications suitable for use in the development of design documents for engineering applications.

An estimation of elastic-plastic stresses and strains is presented for mechanical components, using pseudo elastic analysis based on the deformation theory of plasticity. Analysis of two applicatio...

Experiments have demonstrated that signals in nerve fibers are composed by electrical and mechanical components. In this paper a coupled mathematical model is described which unites the governing equations for the action potential, the pressure wave in the axoplasm and the longitudinal and the transverse waves in the surrounding biomembrane into one system of equations. As a solution of this system, an ensemble of waves is generated. The main hypotheses of such a model are related to the nature of coupling forces between the single waves in the ensemble. These coupling forces are assumed to have bi-polar shapes leading to energetically stable solutions. The in silico modeling demonstrates the qualitative resemblance of computed wave profiles to experimental ones. The ideas of possible experimental validation of the model are briefly described.

This work aimed to produce mechanical components of nickel–titanium shape memory alloys using investment casting processes. Then, in order to validate processing, different designs of nickel–titanium shape memory alloy components as staple implants, Belleville springs, meshes, helical springs, screws and hexagonal honeycombs were produced and submitted to thermal and mechanical characterization. Thermoelastic martensitic transformation of the nickel–titanium shape memory alloy parts was determined by differential scanning calorimetry and electrical resistance with temperature, while the superelastic behaviour was verified by cyclic tensile and compression tests. It has been demonstrated that the employed investment casting processes are suitable to manufacture nickel–titanium shape memory alloy mechanical components with simple and complicated designs as well as functional properties related to phase transformation and superelasticity.

Angular contact ball bearing (ACBB) is widely used in rotating machinery for its great external load capacity. The operating condition of ACBB is easily affected by surrounding mechanical components. The variations of contact angles and load distributions can sufficiently reflect the operating condition of ACBB. A localized defect on the raceway will lead to the dramatic change of contact angle and load distribution of ACBB. In this paper, a mechanical model of ACBB with a localized defect on outer raceway is established, in which the effects of centrifugal force and gyroscopic moment on the force equilibrium relation of balls in high speed operating condition are considered. The proposed model is verified by comparing with the existing model in literature. On the basis of the proposed bearing model, the effects of some parameters on the variations of contact angles and load distributions are investigated. The results show that as the operating speed increases, the centrifugal forces of balls increase and the balls are gradually moving towards outer raceway, which results in that the load distributions between balls and outer raceway are much larger than those between balls and inner raceway. In view of the combined external forces and moments acted on the bearing, the variations of contact angles and load distributions become more complicated than those under the single force or moment applied condition. With the increase of the circumferential extent of localized defect, abrupt changes of contact angles and load distributions in defect area increase obviously.

Understanding the defect characterization of electronic and mechanical components is a crucial step in diagnosing component lifetime. Technologies for determining reliability, such as thermal modeling, cohesion modeling, statistical distribution, and entropy generation analysis, have been developed widely. Defect analysis based on the irreversibility entropy generation methodology is favorable for electronic and mechanical components because the second law of thermodynamics plays a unique role in the analysis of various damage assessment problems encountered in the engineering field. In recent years, numerical and theoretical studies involving entropy generation methodologies have been carried out to predict and diagnose the lifetime of electronic and mechanical components. This work aimed to review previous defect analysis studies that used entropy generation methodologies for electronic and mechanical components. The methodologies are classified into two categories, namely, damage analysis for electronic devices and defect diagnosis for mechanical components. Entropy generation formulations are also divided into two detailed derivations and are summarized and discussed by combining their applications. This work is expected to clarify the relationship among entropy generation methodologies, and benefit the research and development of reliable engineering components.

There are many mechanical components and complex structures in the aircraft gun weapon system of armed helicopters. It is difficult to diagnose only on the basis of maintenance experience of aircraft personnel. In order to improve the efficiency of fault diagnosis, the intelligent fault diagnosis method based on BP neural network is adopted. Through the collection, analysis and arrangement of a large number of fault phenomena, the cause of the failure and the fault sample, the intelligent diagnosis model of aircraft gun weapon system is established by BP neural network. It reflects the fault diagnosis process and its effect. The system has the advantages of high accuracy of the system diagnosis result, the fault treatment efficiency is effectively improved. It provides a scientific decision basis for the implementation of battlefield repair, and it has important practical application value.

The materials such as Al 2024-T3, Mg AZ31B, and Ti–6Al–4V are mostly used in various mechanical components that subject to very harsh operating environment. These components may be prone to various kinds of loadings such as impact, blast, and fire. The behavioral study of the response of these components under such loadings is complex due to dynamic nature of the loadings. It becomes more challenging when it is under a thermal environment that means at various temperatures. In the present study, a Continuum Damage Mechanics model is used to predict the behavior of these materials subjected to ballistic impact, blast and fire loading considering various levels of plate temperatures. The temperature and strain rate dependent Johnson–Cook model is implemented in ABAQUS/Explicit using VDLOAD and VDFLUX user subroutines for blast and fire loading, respectively. The localized temperature rises in the plates due to plasticity is studied at various plate temperatures. The comparative investigation is performed by varying plate temperatures and loading conditions. The results can be interpreted for usage of these materials in various aerospace and structural applications.

Fatigue as a mode of failure becomes increasingly relevant with age in tissues that experience repeated fluctuations in loading. While there has been a growing focus on the mechanics of networks of collagen fibers, which are recognized as the predominant mechanical components of soft tissues, the network's fatigue behavior has received less attention. Specifically, it must be asked (1) how the fatigue of networks differs from that of its component fibers, and (2) whether this difference in fatigue behaviors is affected by changes in the network's architecture. In the present study, we simulated cyclic uniaxial loading of Voronoi networks to model fatigue experiments performed on reconstituted collagen gels. Collagen gels were cast into dog-bone shape molds and were tested on a uniaxial machine under a tension-tension cyclic loading protocol. Simulations were performed on networks modeled as trusses of, on average, 600 nonlinear elastic fibers connected at freely rotating pin-joints. We also simulated fatigue failure of Delaunay, and Erdős-Rényi networks, in addition to Voronoi networks, to compare fatigue behavior among different architectures. The uneven distribution of stresses within the fibers of the unstructured networks resulted in all three network geometries being more endurant than a single fiber or a regular lattice under cyclic loading. Among the different network geometries, for low to moderate external loads, the Delaunay networks showed the best fatigue behavior, while at higher loads, the Voronoi networks performed better.

This paper presents test results and analyses of safety lock wire and cotter pins with castellated nuts used as locking features in threaded fasteners. These mechanical components are used to secure hardware in aerospace and other applications as well as to assess whether a fastener has been tampered with. Tests are performed on aerospace threaded fasteners. Locking moments up to safety lock wire and cotter pin failure are measured. Calculations of locking moment to failure are provided and compared to measured results. For fasteners with safety lock wire, the angle of turn with applied moment is measured and computed. For fasteners with cotter pins and castellated nuts, the angles of turn from clearances and applied moment are computed. Since both safety lock wire and cotter pin with castellated nut applications result in some angle of turn, analysis for loss of preload with angle of turn is developed. Calculations show modest loss in preload for typical angles of turn for long bolts, but a significant loss of preload is found for short bolts.

The use of multibody simulation tools allows complex machinery to be described in detail while still providing a solution for the system in real time. As mechanical components are often accompanied by other dynamical systems, such as hydraulics, description of each subsystem is required to fully describe the dynamics of complex machinery. A potential candidate for solving the multiphysics problem at hand is known as the unified or monolithic approach. This strongly coupled approach yields a single set of equations to be integrated and, compared to co-simulation and co-integration approaches, a relatively simple integration procedure. In this paper, a monolithic formulation for a combined simulation of multibody and hydraulic dynamics using an efficient semi-recursive formulation and the lumped fluid method is introduced. The results indicate that the proposed method shows potential for efficient simulation of combined multibody and hydraulic problems. The robustness of the multibody method is maintained when combined with the hydraulic dynamics description and higher efficiency is observed than with an equivalent global approach.

Fabrication of complex and multi-articulated mechanisms is often seen as a time consuming and demanding process. The development of functional multi-articulated mechanisms that could be fabricated in a single step without the need for post-manufacturing assembly is therefore very attractive. Additive manufacturing (AM) has been pointed out as a feasible solution due to its numerous advantages and high versatility in comparison to other manufacturing techniques. Nevertheless, AM techniques also present different shortcomings that limit the complexity of the mechanism for single step fabrication. Here, we review the applications of AM techniques in fabrication of non-assembly multi-articulated mechanisms and highlight the involved challenges, thereby providing a perspective regarding the advantages and limitations of current AM techniques for production of complex mechanical devices. The paper starts off with basic joint elements in rigid-body and compliant configurations and proceeds with presenting an overview of multiple arrangements of joints and assemblies with embedded mechanical components. For every case of non-assembly fabrication, the limitations of the applicable AM processes are presented and further discussed. This work concludes with a discussion of the major shortcomings found in current non-assembly mechanisms fabricated by AM and recommending alternative techniques and future developments on AM.

Swept-source optical coherence tomography (SS-OCT) is a powerful tool for fast medical imaging. For the real-time three-dimensional imaging, the wide tuning range over 100 nm and fast sweep rate over 100 kHz are typically required. We have proposed a new wavelength-swept laser for SS-OCT. It is based on a principle called dispersion tuning. Since the cavity contains no mechanical components, such as tunable filters, we could achieve the very high sweep rate. In this paper, we describe the principle of the dispersion-tuned swept laser and present our recent works on the applications to the SS-OCT system.

Tolerance analysis of mechanical components and assemblies is a key element in the industry for improving product quality and reducing overall cost. This paper is an attempt to propose a methodolog...

Fatigue is one of the main reasons of fracture in mechanical components. Generally performing experiments is a useful and effective method for determination of fatigue life. In this paper, results of different notch geometry effects on the fatigue life under mixed mode I and III were studied experimentally and numerically. For this purpose, fatigue specimens were manufactured according to the ASTM-A370 standard and all the specimens were quenched and tempered. Two types of notch geometries, V-shape and U-shape were considered in this study. The fatigue life was determined experimentally for each notch geometry and results were verified by finite element method simulation. Fractographic investigation was done broadly to determine cause of failure in the specimens. Our results showed that the notch geometry had significant effect on the fatigue life. Fatigue crack growth in the V-shape notch specimens happened quickly and the maximum fatigue life reduction occurred for that.

Wear is an important factor for failures of mechanical components. Current research on wear is mainly focused on experiments while the numerical simulation of wear is hardly used owing to the complexities of the wear process. Explaining the effect of friction on the wear process is important, as it will lead to a deeper understanding of the evolution of wear. This study proposed a numerical method to expound the wear process in the contact between an elastic cylinder and a half-space simulating the ring-block tester. There are two difficulties during the calculation; one is that the contact shapes vary with time, causing the pressure distribution to change simultaneously and the other is the integral equation for calculating the contact pressure under different worn shapes. In the present study, the wear rate was computed using Archard’s law and the wear process was calculated step by step until the specified total sliding distance was achieved. During each step of the calculation, the contact topography was updated. The simulation intuitively reproduced the contact state of change from line to surface contact throughout the wear process. Reasonable agreements on the changes of the wear scar, achieved from experiments and numerical simulations, were obtained.

In this paper, it is described the design of seedling separation device with reciprocating movement of seedling cups and control system of the full automatic plug seedling transplanter. The analysis of the research indicates that the specific strategic path seedling is plane and corresponding control system is formulated. It is put forward special intention on the specific designing of the main components (transplanting device, seedling device and seedling cup) of the seedling separation device. The linear driving motor and driving cylinder are used to control the reciprocating motion, open and close mechanism of mobile seedling cups. The control schemes of the seedling picking, seedling transmission and seedling dropping are designed in detail. It is assured the control program of picking of seedling in the fixed position and the transmission of seedling rapidly and dropping of seedling in the fixed position. The positioning accuracy tests of the linear transmission device and the success rate tests of the seedling device are carried out separately. It is found that the positioning accuracy of a linear transmission device decreased gradually with the increase of seedling speed, especially when the motor pulse frequency exceeds 20,000 Hz. The motor gets out of steps and the precision will drop rapidly. After that it is optimized the motor by setting different pulse frequencies, and fix the range of error values between 0.2 mm and 0.8 mm which is according to the requirement of seedling location. The results of seedling tests of seedling device indicate that the qualified rate of seedling decreases gradually with the increase of seedling speed and the success rate of 70 working cycles/min is 95.03%. This demonstrates that the structure of mechanical components of seedling separation device meets the sub-seed movement requirements. The optimization of the control system could increase the position accuracy according to requirements and achieve the goal of automated sub seedlings.

The purpose of this study is to measure airtightness of building components in newly constructed apartment buildings in South Korea. For the measurements, electrical, architectural and two mechanical components regarding water and air systems were categorized and air leakage rates of these parts were measured by the blower door test. In addition to these building components, air leakage rates on the entrance door and three different building heights were analyzed. Moreover, the results obtained by the blower door test were compared with the tracer gas measurements. As a result, the air leakage rates (ACH50) were between 0.7 and 1.0 h−1, when all parts were sealed. When unsealing all parts, the ACH50 values ranged from 1.6 to 2.7 h−1. In addition, the ACH50 values were highly influenced by the entrance door and window systems. By improving the windows and the entrance door, the air leakages can be significantly reduced in residential buildings. Furthermore, the comparison results obtained by the tracer gas and blower door showed that artificially produced pressure difference condition can cause the overestimated ACH value.

In the manufacturing field, the assembly process heavily affects product final quality and cost. Specific studies, concerning the causes of the assembly defects, showed that operator errors account for high percentage of the total defects. Also, models linking the assembly complexity with the operator-induced defect rate were developed. Basing on these models, the present paper proposes a new paradigm for designing inspection strategies in case of short-run productions, for which traditional approaches may not be carried out. Specifically, defect generation models are developed to get a priori predictions of the probability of occurrence of defects, which are useful for designing effective inspection procedures. The proposed methodology is applied to a case study concerning the assembly of mechanical components in the manufacturing of hardness testing machines.