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Hlavním cílem tohoto článku je popis viskozity a chování materiálu PA 6 se skelnými vlákny při plnění. Vstřikování plastů je jednou z nejčastěji používaných výrobních metod. Kvalita výsledného produktu je spojena s nastavenými parametry vstřikovacího procesu. Je nutné správně pochopit proces plnění formy a proto byl proveden tento výzkum. Spirálový test zatékavosti byl proveden, proto aby byly zjištěny vlivy různých parametrů na celkové plnění formy. Jako výsledný parametr byla srovnána celková délka spirály. Testovaný materiál byl PA6 s 15% skelných vláken (výrobní název Durethan BKV 15). Pro validaci byly provedeny virtuální simulace. Byla zjištěna lineární závislost mezi stupňem naplnění a ostatními parametry. Pro tento test byla navržena a vyrobena speciální forma. The main aim of this paper was to describe the viscosity and injection mold filling behavior of PA6 with 15% of glass fibers. Injection molding is one of the most widely used processes for polymer products. The quality of these products is directly linked to correct choice of process parameters. It is necessary to understand the filling behavior of the polymer material during the injection molding process. The spiral flow test was carried out in this study to explore the effects of several injection process parameters. The resulting lengths of spiral flow were compared. The polymer material under test was Polyamide 6 with 15% of short glass fibers (trade name: Durethan BKV 15). Virtual testing as well as real testing was performed. A predominantly linear relationship between the flow length and the mold temperature, melt temperature and injection pressure is described here. A special mold was designed for this test.

At the Alcoy Campus of the Universitat Politècnica de València, we were challenged to obtain the first double degree for our campus. This double degree was established for a Mechanical Engineering major, and our partner institution was Ostfalia Hochschule für Angewandte Wissenschaften, located in Wolfenbüttel campus. The agreement between the schools was signed in 2012, after three years of work. Students from either university could get an official diploma in Mechanical Engineering at both universities if they spent two consecutive semesters in the partner institution. This has many benefits for students and professors, which will be discussed in this paper, along with the main process followed to arrive to the final agreement.

This paper deals with the flexural stiffness of sandwich structures based on fiberglass and polymeric foams. The influence of geometrical and material parameters on the resulting effective flexural stiffness of the sandwich structure is being studied experimentally, analytically and using FEM models. The effective elasticity module of the sandwich-structured element is being studied and it’s theoretical and model dependencies on the stiffness of the foam core are being investigated. These dependencies are then compared with experimentally observed values. This study shows it is necessary to pay special attention to the issue of flexural stiffness of walls when designing sandwich shell products in order to prevent possible failures in the practical applications of these types of structures. © 2016 Trans Tech Publications, Switzerland.

This paper shows the authors experience in the implementation of cooperative learning during the fourth year of the Mechanical Engineering Grade, having involved from the second to the fourth year. Difficulties encountered are discussed.

This paper investigates the torsional load capacity of three sizes of V-section band clamps when assembled onto rigid flanges by comparing experimental data with a developed theoretical model. This mode of failure is of particular interest for turbocharger applications where, in use, they are subjected to torsional loading via thermal and vibrational effects. The theoretical model developed allows the impact on torsional load capacity of a number of joint parameters to be investigated and good correlation of the results, incorporating variations in coefficients of friction and dimensions, has been shown for the two larger band sizes. For smaller diameter bands, the experimental data suggests that as the band is tightened, contact with the flange is localised rather than being over the full circumference of the band. The coefficients of friction, in particular that between the flanges, and the position of the contact point between band and flange have been shown to have a significant impact on the theoretical torsional load capacity of V-section band clamps.

This paper aims to emphasize the necessity of introducing Project-Based Learning (PBL) to design enterprises in order to foster designers creativity and facilitate innovation of design enterprises. According to the literature review, creativity can be viewed as the first stage of innovation; PBL has at least two elements including solving real problems and group work that can provide conditions of creativity development. Moreover, creativity techniques such as brainstorming, mind mapping, checklist and morphological analysis are suggested to be integrated into PBL in the design enterprises.

This paper presents a review of creep cavitation and rupture of low Cr alloy and its weldment, particular in the heat-affected zone (HAZ). Creep damage is one of the serious problems for the high temperature industry. One of the computational approaches is continuum damage mechanics which has been developed and applied complementary to the experimental approach and assists in the safe operation. However, the existing creep damage constitutive equations are not developed specifically for low stress. Therefore, in order to form the physical bases for the development of creep damage constitutive equation, it is necessary to critically review the creep cavitation and rupture characteristics of low Cr alloy and its weldment.

Conventional condition monitoring techniques such as vibration, acoustic, ultrasonic and thermal techniques require additional equipment such as sensors, data acquisition and data processing systems which are expensive and complicated. In the meantime modern sensorless flux vector controlled drives can provide many different data accessible for machine control which has not been explored fully for the purpose of condition monitoring. In this paper polynomial models are employed to describe nonlinear relationships of variables available from such drives and to generate residuals for real time fault detection and performance comparisons. Both transient and steady state system behaviours have been investigated for optimal detection performance. Amongst 27 variables available from the drive, the torque related variables including motor current, Id, Iq currents and torque signals show changes due to mechanical misalignments. So only these variables are explored for developing and optimising detection schemes. Preliminary results obtained based on a motor gearbox system show that the torque feedback signal, in both the steady and transient operations, has the highest detection capability whereas the field current signal shows the least sensitivity to such faults.

The aim of the present paper is to provide a state-of-the-art outline of structural health monitoring (SHM) techniques, utilizing temperature, noise and vibration, for wind turbine blades, and subsequently perform a typology on the basis of the typical four damage identification levels in SHM. Before presenting the state-of-the-art outline, descriptions of structural damages typically occurring in wind turbine blades are provided along with a brief description of the four damage identification levels.

As wind turbines increase in magnitude without a proportional increase in stiffness, the risk of dynamic instability is believed to increase. Wind turbines are time dependent systems due to the coupling between degrees of freedom defined in the fixed and moving frames of reference, which may trigger off internal resonances. Further, the rotational speed of the rotor is not constant due to the stochastic turbulence, which may also influence the stability. In this paper, a robust measure of the dynamic stability of wind turbines is suggested, which takes the collective blade pitch control and non-linear aero-elasticity into consideration. The stability of the wind turbine is determined by the maximum Lyapunov exponent of the system, which is operated directly on the non-linear state vector differential equations. Numerical examples show that this approach is promising for stability identification of the non-linear wind turbine system.

The aim of this study is to present an efficient and accurate method for estimation of the failure probability of wind turbine structures which work under turbulent wind load. The classical method for this is to fit one of the extreme value probability distribution functions to the extracted maxima of the response of wind turbine. However this approach may contain high amount of uncertainty due to the arbitrariness of the data and the distributions chosen. Therefore less uncertain methods are meaningful in this direction. The most natural approach in this respect is Monte Carlo (MC) simulation. This is not practical due to its excessive computational load. This problem can alternatively be tackled if the evolution of the probability density function (PDF) of the response process can be realized. The evolutionary PDF can then be integrated on the boundaries of theproblem. For this reason we propose to use the Probability Density Evolution Method (PDEM). PDEM can alternatively be used to obtain the distribution of the extreme values of the response process by simulation. This approach requires less computational effort than integrating the evolution of the PDF; but may be less accurate. In this paper we present the results of failure probabilityestimation using PDEM. The results will then be compared to extrapolated values obtained from extreme value distribution fits to the sample response values. The results approve the feasibility of this approach for reliability analysis of wind turbines however they convey the potential for improving accuracy of the method in low probability areas

The aim of the present paper is to evaluate structural health monitoring (SHM) techniques based on modal analysis for crack detection in small wind turbine blades. A finite element (FE) model calibrated to measured modal parameters will be introduced to cracks with different sizes along one edge of the blade. Changes in modal parameters from the FE model are compared with data obtained from experimental tests. These comparisons will be used to validate the FE model and subsequently discuss the usability of SHM techniques based on modal parameters for condition monitoring of wind turbine blades.

In this paper we report on optical absorption measurements performed on several metal oxide nanoparticles (ZnO, CeO2, Fe2O3) as a function of temperature in the range 25500 °C, in order to study the optical properties, and to investigate how several heating cycles could affect nanoparticle structural stability and absorption characteristics. These are quite important issues to be investigated in order to assess the possibility to use such metal-oxide nanoparticles as gas-based high temperature nanofluid in concentrated solar power (CSP).

Proceedings of: 8th International Symposium on Impact Engineering (ISIE 2013). Osaka, Japan, September 02-06, 2013. In this paper we analyze, using the Finite Element Method, the process of brittle-ductile transition in the failure mode observed in polycarbonate notched specimens under impact loads. In order to analyze this transition we have implemented, through a user subroutine, a damage model which combines a tensional fracture criterion and an energetic, acting simultaneously. The competition between both criteria predicts the difference in material behavior from a critical impact velocity, and how this transition is produced on different planes through the thickness of the specimen. These results show the necessity of employing three-dimensional models for its study. Authors thank the Comisión Interministerial de Ciencia y Tecnología of the Spanish Government for the support of this work through the Research Project DPI2011-23191. Publicado

Assessment of concrete strength in existing structures is a very fundamental task today, because the mechanical characteristics are strictly connected to seismic protection and performance estimation of the material. To this aim, several compression tests has been carried out on drilled core samples in conjunction with different NDT methods. The activity presented in the paper is still under development and is intended as a reference in the choice of the methods and correlations for structural survey of existing buildings.

This paper proposes the validity of a Gabor filter bank for feature extraction of solder joint images on Printed Circuit Boards (PCBs). A distance measure based on the Mahalanobis Cosine metric is also presented for classification of five different types of solder joints. From the experimental results, this methodology achieved high accuracy and a well generalised performance. This can be an effective method to reduce cost and improve quality in the production of PCBs in the manufacturing industry.

Fuels for future fast reactors will not only produce energy, but they must also actively contribute to the minimisation of long lived wastes produced by these, and other reactor systems. The fuels must incorporate minor actinides (MA = Np, Am, Cm) for neutron transmutation into short lived isotopes. Within Europe oxide fuels are favoured. Transmutation can be considered in homogeneous or heterogeneous reactor recycle modes (i.e. in fuels or targets, respectively). Fabrication of such fuels can be made by advanced liquid processing methods, enabling property determination and screening irradiation experiments. This paper will describe these fabrication processes, and discuss properties and fuel irradiation experiments made to date. Both fertile and inert matrix fuel types are considered., JRC.DG.E.4-Nuclear fuels

A simple yet accurate macroscopic constitutive model of shape memory alloys has been developed. The features of this model are (1) energy-based phase transformation criterion, (2) one-dimensional phase transformation rule based on a micromechanical viewpoint, (3) dissipated energy with a form of a sum of two exponential functions, (4) duplication of the strain rate effect, and (5) adaptability to multi-phase transformation. This model is further improved to be able to express stress-strain relationships such that the reverse transformation starts at a higher stress than the martensitic transformation starts. Here, the ideal reversible transformation temperature is empirically described by a function of the martensite volume fraction. In this paper, an outline of our model is given, where the improvement is introduced. Then, it is shown that the model can quantitatively duplicate the major and minor hysteresis loops, strain rate effect, and asymmetry in tension and compression on the stress-strain relationship. And that it can also duplicate the stress-strain relationships having the reverse transformation start stress higher than the forward one.

This paper presents a new method for sputtering solar selective absorber coatings. Radio frequency magnetron reactive sputtering created stainless steel/stainless steel nitride (SS/SS-N) cermet (ceramic-metal composite) thin films under varied nitrogen gas flow ratios. In this present study, a stainless steel material is used for one-target sputtering to manufacture a solar selective absorber film having good solar absorptance of 0.91 and low thermal emittance of 0.06. This sputtering process shows considerable and stable usefulness due to the anti-oxidation and single target. Optical constants n and k have been determined by spectroscopic ellipsometry for cermet composite in a reactive gas flow from 0 percent to 50 percent. Based on the nitrogen content of the film, we used a different oscillator to analyze the film. When the nitrogen gas flow reaches 10 percent, the sputtered film has a significant transformation from metal to cermet properties. When the nitrogen gas flow goes above 17.5 percent, then the film transforms to a dielectric film which can be an anti-reflection layer. A solar absorptance of 0.92 was accepted as the theoretical prediction of optimal selective solar-absorbing three-layer processes which shows that the experimental results agree well with the theoretical prediction.

Textile integration of smart sensor systems is the key technology for the success of future e-garments oriented to emergency operators. Ubiquitous recording and transmission of human and environmental data will allow combining comfort and protection leveraging with the existing smart textile, microelectronics and telecommunication technologies. The challenge offered by emergency situation is mainly in the difficulty to acquire data in a very aggressive environment, during hard physical activity; conditions that will increase the risks of signals artefacts, as well as the presence of positive and negative false events. Security is addressed through the implementation of systems combining body sensing platform, for health alertness and environment sensing platform for context awareness; the full system has also to guarantee protective functionality. State of art textile technology allows the monitoring of heart and respiratory rate, humidity rate, activity rate, GSR and EMG, while core and external temperature, posture via accelerometers, absolute position via GPS are easily monitored through standard sensors. The body sensing platform requires a direct contact with the operator skin leading to the implementation of a sensing inner garment, at the same time environment platform are integrated in a protective jacket that is also hosting the alarm systems and the electronic unit for signal processing and transmission hardware. This paper is reporting about a study done with a pioneer e-textile system named Wealthy on healthy subjects during extreme conditions. Wealthy platform is currently evolving in a new one, specially designed for emergency scenarios, developed in the frame of the project Proetex, a preliminary description of the new system is presented; the new system that is under first testing phase, has been designed to be used without interfering with operator activities.

In the shape memory alloys (SMAs) the thermal triggering induces reversible dimensional change by the phase transformation – these materials may also be ferrior ferromagnetic, however, here only the ferromagnetic SMAs are discussed. In certain SMAs the austenitemartensite phase transformation is influenced by the magnetic field as either austenite or martensite is promoted by the field and this is exploited for the dimensional changes. However, in the magnetic shape memory (MSM) alloys no phase transformation occurs as the remarkable dimensional changes take place by the twin variant changes in the martensitic phase activated by the external magnetic field at constant temperature. In addition to the phase transformation or magnetic shape memory effect, the applied magnetic field may also result in the conventional magnetostriction (MS), enhance the superelasticity (magneticfieldassisted superelasticity MFAS) or induce the giant magnetocaloric effect (GMCE). Certain alloys such as NiMnGa may even be multifunctional showing more than one of these effects. The present paper gives an overview of the different types of the magnetically activated SMA alloys, their properties as well as their potentials for applications in the frameworks of the recent studies.

A no-power 3-axis bidirectional MEMS threshold accelerometer is presented in this paper. Threshold accelerometers of 25g, 50g, and 100g were designed and fabricated on a single 3mm chip. The design is based on a conductive spring-mass system made of Au metal layers that close a switch between two metal contacts when the designed threshold is exceeded. We present the MEMS threshold accelerometer switch fabrication process and provide an analytical and experimental framework for the device performance

This paper covers circuits and systems techniques for the construction of high reliability biosensing and stimulation medical devices. Such microsystems are dedicated for interconnections through either the central or the peripheral nervous systems. Low-power high-reliability wireless links are used to power up the implanted devices while data are exchanged bidirectionaly between these implants and external controllers. A global view of main devices is given, case studies related to applications such as bladder control, intracortical monitoring and microstimulation are discussed, altogether with modeling, characterization, as well as microsystems assembly and packaging. Also, dedicated electrode arrays and their interfaces to tissues interfaces are summarized.

Quartz length-extension resonators have already been used to get atomically-resolved imaging by frequency-modulation atomic force microscopy. Other piezoelectric materials could be appropriate for this application. Theoretical study is reported on Langasite length extension resonator. In this paper, an attempt to fabricate similar micro resonators in Langasite temperaturecompensated cuts is prospected.

This paper presents a strain monitoring approach for following up FRP elements (in this case a [90°] CFRP laminate) using an embedded fibre optic sensor. The sensor exists of two fibre Bragg gratings (FBGs) written in a polarization maintaining fibre (PMF). First, the strain response of the non-embedded sensor is determined which makes it possible to relate the different bragg peak shifts with the induced strain field in the core of the optical fibre. Secondly, a transfer coefficient matrix is presented and calculated using finite element simulations which relates the measured strain field of the sensor with the adjacent one existing in the structure as if no sensor would be present.

Water is an essential requirement in everyday life and global demand for clean usable water is increasing year by year. Therefore, developing and implementing effective water resource management and conservation strategies is vital. Generally speaking, most individuals (particularly senior citizens) prefer to use warm water when washing their hands or taking a bath. When hot water is left standing in the hot water pipe (i.e. the faucet is turned off), it will gradually cool. Consequently, when the faucet is first turned on, the water is generally allowed to run until it becomes sufficiently hot. Meanwhile, the original cooler water is simply drained away. Clearly, this approach is wasteful of both time and water. Therefore, this paper develops a green storage tank to perform a thermo-controlled water supply function. The tank is positioned between the hot water supply and the faucet and its operation is controlled by an electro-thermal thin-film heater and a thermo-controlled valve. When the faucet is turned on, the cooler water in the hot water pipe is directed into the tank. Once this water enters the tank, it is mixed with hot water stored inside until it acquires the desired temperature. The warmed water is then supplied to the faucet. When the water flowing through the hot pipe to the tank is already sufficiently warm for use, the thermo-controlled water supply function is automatically overridden, and the warm water is delivered directly to the faucet. The proposed green storage tank not only provides effective water and energy resource savings, but also provides a more convenient operation.

This paper presents ride comfort analysis of a full-vehicle featuring controllable magnetorheological (MR) shock absorbers. In order to achieve this goal, two flow mode MR shock absorbers (one for front suspension; one for rear suspension) are designed using an optimization methodology based on design specifications for a commercial passenger vehicle. The optimization problem is to find optimal geometric dimensions of the magnetic parts for the front and rear MR shock absorbers in order to improve the performance such as damping force. After manufacturing the proposed MR shock absorbers, their field-dependent damping forces are experimentally evaluated. The governing equation of motion for the full-vehicle is then established and integrated with the model of the MR shock absorbers. Subsequently, skyhook controllers for the MR suspensions are formulated and implemented. Ride comfort performances of the full-vehicle installed with the proposed MR shock absorbers are evaluated under bump and random road.

This paper describes the development of a mechanized wing concept for a perching micro air vehicle. The wings are capable of rotating in pitch at two spanwise joints to simulate the motion of a bird’s wings during a perching maneuver. This project focuses on the wing mechanization design and analysis as well as the structure/mechanism integration. The advantage of a perching type of landing is that it allows the vehicle to land with approximately zero vertical and horizontal velocity on a tree branch, power line, or ledge. The requirements to perform this maneuver were investigated, the structural design was developed, and the mechanization integration to achieve this motion was determined. A model was designed and manufactured to demonstrate the kinematic mechanism making this wing motion possible. Wind tunnel testing and analytical simulation were also completed to further develop the model.

IPMCs are one of the most promising smart actuators to replace traditional actuators for some specific applications particularly in the micro-nano scales. IPMC actuator’s shape and configuration have a dramatic effect on the actuation parameters. While the behaviour of IPMCs as a single fixed end strip actuator (cantilever) has been widely studied since the early 80’s, its behaviour in other configurations is relatively unknown. This paper presents work carried out in order to reconfigure these actuators for some new applications. The first configuration is when both ends of an IPMC actuator strip are fully constrained, in both the actuator plane and the normal direction. In this case the displacement and force measurements at the mid point of the strip are presented. The results of a series of experiments show the behaviour of the actuator in this configuration and using these results some models have been proposed. The second configuration is when only one end of the strip is fixed and the other end is constrained in the normal direction with respect to the plane of the actuator strip. A series of experiments were also carried out to explore the IPMC actuator behaviour in terms of maximum displacement and force generated in this configuration. The behaviour of the IPMC actuator in these two configurations is also investigated by studying the internal stresses in the IPMC structure.

Rhythmic movements associated with animal locomotion are controlled by neuronal circuits known as central pattern generators (CPG). These biological control systems appear to entrain to the natural frequencies of the mechanical systems they control, taking advantage of the resonance of the structure, resulting in efficient control. The ultimate goal is employing these controls in a biomimetic autonomous underwater vehicle so as to capture, and possibly improve upon, the performance capabilities of animals like the manta ray. To this end, this paper investigates the CPG control of a simple tensegrity structure. The dynamics of a tensegrity structure are linearized about a nominal configuration, and a synthesized CPG is used as the control input. Successful integration is shown by the CPG's ability to tune the structure's first mode.

Lithographic processes belong to the most critical steps in the fabrication of microelectronic circuits. Optical projection lithography which transfers the layout of a mask into a photoresist at the top surface of a silicon wafer is still the workhorse of semiconductor industry. Many innovations regarding the optical imaging system and the introduction of new mask technologies have pushed optical projection techniques close to their theoretical limits. Nowadays, optical projection lithography is used to create 45nm features with a wavelength of 193nm. This paper discusses the impact of the mask on the performance of a lithographic process. For large feature sizes the mask can be considered as infinitely thin and its local transmission and phase can be directly derived from the design. For mask features comparable to the wavelength of the used light and below, the mask becomes a complex scattering object which has a pronounced impact on the intensity, phase, and polarization of the diffracted light. The light diffraction from the mask has to be computed by rigorous electromagnetic methods. Several consequences with respect to the choice of most appropriate mask materials and geometries will be discussed.

Myliobatidae is a family of large pelagic rays including cownose, eagle and manta rays. They are extremely efficient swimmers, can cruise at high speeds and can perform turn-on-a-dime maneuvering, making these fishes excellent inspiration for an autonomous underwater vehicle. Myliobatoids have been studied extensively from a biological perspective; however the fluid mechanisms that produce thrust for their large-amplitude oscillatory-style pectoral fin flapping are unknown. An experimental robotic flapping wing has been developed that closely matches the camber and planform shapes of myliobatoids. The wing can produce significant spanwise curvature, phase delays down the span, and oscillating frequencies of up to 1 Hz, capturing the dominant kinematic modes of flapping for myliobatoids. This paper uses dye flow visualization to qualitatively characterize the fluid mechanisms at work during steady-state oscillation. It is shown that oscillatory swimming uses fundamentally different fluid mechanisms than undulatory swimming by the generation of leading-edge vortices. Lessons are distilled from studying the fluid dynamics of myliobatoids that can be applied to the design of biomimetic underwater vehicles using morphing wing technology.