Search

This paper presents modeling and simulation of a cantilever-type piezoelectric energy harvester based on a combined FEM (Finite Element Method) and spice circuit. The PEH having dimension of 61 mm × 37 mm × 0.4 mm provides the maximum output power of 8 mW at resonant frequency of 127 Hz. The fabricated cantilever-type PEH (Piezoelectric Energy Harvester) has been characterized with variable resistor, which reveals that maximum power transfer is achieved at 10 kΩ. The modeling and simulation have beenperformed to study the effect of piezoelectric layer thickness on PEH output power in case of load resistance. FEM modeling and simulations have been carried out to extract electrical elements such as Rm, Lm, Cm, Cp and Γ. Those electrical elements have been included into a spice model to find optimal load resistance for maximum power transfer as well as. frequency response as function of piezoelectric layer thickness. Experiment and simulation show a good agreement on optimal load resistance. [ABSTRACT FROM AUTHOR]

Wildfire evacuation triggers refer to prominent geographic features used in wildfire evacuation practices, and when a fire crosses a feature, an evacuation warning is issued to the communities or firefighters in the path of the fire. The existing wildfire trigger modeling methods consider evacuation time as an input from a decision maker and employ fire spread modeling and GIS to create a trigger buffer around a threatened asset. This paper substantially improves on previous methods by coupling fire and traffic simulation models to set triggers, which allows us to estimate evacuation time using a traffic simulation model rather than relying on expert judgment. Specifically, we propose a three-step method within a spatiotemporal GIS framework to couple these models and to evaluate the value of the generated trigger buffers. The first step uses traffic simulation to estimate the total evacuation time for a threatened community. The second step derives the cumulative probabilities for distinct evacuation times from multiple simulations and generates corresponding probability-based trigger buffers. In the last step, we evaluate the value of the generated buffers by coupling fire and traffic simulation models to examine the spatial configurations of fire perimeters and evacuation traffic. A case study of Julian, California is used to test the proposed method. The results from two evacuation scenarios with different travel demand indicate that a larger trigger buffer (more lead time) will be needed for higher levels of evacuation travel demand. For example, the time required to guarantee that 95% of the evacuating residents arrive at the safe area as a fire approaches a community is estimated at 160 min for one scenario but 292 min if the travel demand is doubled. The resulting framework advances the dynamic representation of evacuation traffic in wildfires and improves our understanding of wildfire evacuation timing and decision making. The paper concludes with a discussion of the strengths and limitations of the proposed method, as well as future research directions. [ABSTRACT FROM AUTHOR]

Research on capsule robotics has been going on for many years, it has extensively applied to the field of endoscopy. The biggest advantage of capsule robots is that they can be swallowed, move in narrow channels, drug delivery and surgery. However, to make itself be able to move in tight spaces, capsule robot must keep its volume small enough which means it also becomes the biggest challenge of the development of capsule robots. This paper carried out a series of simulations and experiments in order to evaluate the characteristic influence of different structures on motion performance for a magnetic-actuated screw jet microrobot (SJM). The whole system consists of three main parts, the power supply section, three-axes Helmholtz coils are to provide a uniform controllable rotating magnetic field; the simulated intestinal part, a transparent plastic pipe; a screw jet microrobot, it consists a radially magnetized O-ring type neodymium magnet and a rotating screw jet structure. Although we carried out this kind of robot over past few months, it still has a lot of uncertainty on the motion performance. The previous papers have proposed this type of magnetic actuated screw jet microrobot and its driving device, principle, etc., since we proved it can run smoothly (extra degree of freedom that enables various advanced functions such as axial position control). The research in paper consists of three evaluation parts, separately evaluated shell, screw, and different liquid environments. The first part evaluated the inlet and outlet size on the shell section, as for the second part, we evaluated the effect on screw with different pitch. The last part of the experiment is about experimenting different kinds of liquid. We also did the simulations and discussed about the motion performance in order to make sure that our results is realizable before the experiments. Combining the simulation results and experimental results, we will discuss the optimal choice of the design by the simulation in an ideal environment and the comparison of experimental results. [ABSTRACT FROM AUTHOR]

Clinch joining is a complexed mechanical behavior influenced by both process parameters and geometry parameters. The present clinch joining optimizations are more dedicated on geometry parameters, and except some property objectives of optimization, the other design properties of clinching process are not considered as constrained conditions. Therefore, the multiobjective optimization in the paper takes clinching process parameters such as punch speed, bottom thickness, and blank holder force into consideration besides geometry parameters, and then sets two thinning rates as constrained conditions. In the paper, a sufficient and systemic procedure for high-quality clinched joint based on FEA (finite element analysis), PS (parameter study), RSM (response surface methodology), and NSGA-II (non-dominated sorting genetic algorithm-II) is developed. Parameter study is conducted to choose significant parameters from both process and geometric parameters for neck, interlock, and tensile force. Then, mathematical models of nine selected parameters with responses are built based on RSM, and the interactions on interlock and tensile force are clearly identified by the model. Finally, three objectives neck, interlock, and tensile force and two constraints thinning rates of side face of joint are applied on multiobjective optimization using NSGA-II, which could obtain comprehensive high-quality joint, and the Pareto sets reveal negative relations of both tensile force to neck and interlock to neck, as well as the positive relation between interlock and tensile force. The result shows that the presented procedure performs well in optimization of clinch joining process and the use of finite element simulation model is valuable for complex optimization design. [ABSTRACT FROM AUTHOR]

The paper presents the process of homogenization of the composite material properties obtained by method of continuous source functions developed for simulation both elasticity and heat conduction in composite material reinforced by finite-length regularly distributed, parallel, overlapping fibres. The interaction (fibre-fibre, fibre-matrix) of physical micro-fields influences the composite behaviour. Comparing with finite element method (FEM), the interaction can be simulated either by very fine FE mesh or the interaction is smoothed. The presented computational method is a mesh-reducing boundary meshless type method. The increase in computational efficiency is obtained by use of parallel MATLAB in presented computational models. The stiffness/conductivity is incrementally reduced starting with superconductive/rigid material properties of fibres and the fibre-matrix interface boundary conditions are satisfied by the iterative procedure. The computational examples presented in paper show the homogenized properties of finite-length fibre composites; the thermal and elasticity behaviour of the finite-length fibre composites; the similarities and differences in composite behaviour in thermal and elasticity problems; the control volume element for homogenization of composite materials reinforced by finite-length fibres with the large aspect ratio (length/diameter). The behaviour of the finite-length fibre composite will be shown in similar the heat conduction and elasticity problems. Moreover, the paper provides the possibilities and difficulties connected with present numerical models and suggested ways for further developments. [ABSTRACT FROM AUTHOR]

This paper presents the development of a FE-simulation model to predict the mechanical stresses and thermal loads that a cutting tool of polycrystalline cubic boron nitride (pcBN) is subjected to, when machining AISI 316L. The serrated chip formation of AISI 316L has a major impact on the periodic loads acting on the cutting tool. Therefore, it is vital to correctly model this serrated chip formation. One of the major difficulties with FE-simulations of metal cutting is that the extreme deformations in the workpiece material, often leads to a highly distorted mesh. This paper uses the Coupled Eulerian-Lagrangian (CEL) formulation in Abaqus/Explicit, where the workpiece is modelled with the Eulerian formulation and the cutting tool by the Lagrangian one. This CEL formulation enables to completely avoid mesh distortion. To capture the chip serration process, the workpiece material is described with the Johnson-Cook damage model. The FE-simulation results are validated via comparison of the modelled cutting forces, chip serration frequency, and contact length against experimental ones. [ABSTRACT FROM AUTHOR]

Motorized spindle is an inevitable choice of precision machine, but it has a prominent heat problem for its specific configuration of build-in motor. The paper proposed temperature distribution and thermal deformation modeling and a thermal-structural coupling simulation analysis method for a motorized spindle system from a vertical machining center. In order to establish an accurate finite element model, the boundary condition of joint thermal contact resistance (TCR) was taken into account. The paper detailed on how to obtain the TCR value which is related to the machine tool parameters by means of experimental and theoretical methods, and carried out a simulation experiment for the purpose of acquiring a quantitative analysis of the TCR influence on the temperature results. In order to verify the effectiveness of the TCR relevant methods, the experiment was carried out. The agreement between the experimental results and the simulation results showed that the proposed method can more accurately simulate the thermal characteristics of the motorized spindle. [ABSTRACT FROM AUTHOR]

This paper presents the design, fabrication and experimental characterization of an electro-thermally actuated microgripper suitable for single-cell manipulation. The analysis of the mechanical properties of cells is of great interest both in medicine and biology because the study of the cellular mechanical behaviour and resistance is necessary in these fields. Microgrippers (Bio-MEMS) have an important role in the manipulation of biological tissues and cells. In recent works, the research group simulated the mechanical behavior of grippers and the different actuation strategies. Considering the dimensional specifications and targets imposed by actuation and biocompatibility, in this paper, a microgripper based on electro-thermal actuation is studied. Starting from previous numerical results, a novel SU8 structure is designed and realized according to the micro-fabrication constraints and then the structure is simulated using the finite element method (FEM)-based thermo-structural simulations in ANSYS. Therefore, the fabrication method and steps are presented and the gripper has been developed and tested. Finally, the tip displacements of the gripper, electro-thermally actuated in different operating conditions, are compared with those obtained by means of numerical FEM simulations. A good agreement is obtained between simulations and experimental results. [ABSTRACT FROM AUTHOR]

Residual stress (RS) of machined surface is one of essential factors affecting the service performance of mechanical structures and parts. By a combination of cutting experiment, theoretical analysis, and finite element analysis, this paper focuses on the radial distribution of RS of machined surfaces of a coated carbide microgroove turning tool (CCMTT), firstly, in the turning of the high strength alloy steel. The effect of cutting parameters on the radial distribution of RS of machined surfaces produced by the CCMTT is further researched. Finally, the prediction model of RS produced by the CCMTT is established and verified. Research results show that the cutting experiments and FE simulation both have the same variation tendency of RS and are validated well each other. The microgroove on the rake face of the CCMT is beneficial to increase the thickness and the maximum value of residual compressive stress of surface material. The coefficient of multiple correlation of the forecasting model of surface residual stress (SRS) machined by the CCMTT reaches 97.4%, which illustrates that the model has relatively high reliability. [ABSTRACT FROM AUTHOR]

In this paper, a 3D simulation model for nanosecond pulsed laser engraving process is developed, using the finite element method (FEM) aiming at the prediction of the final geometry of the workpiece and optimizing the process. A general heat transfer model is adapted where the incidence laser beam causing the material ablation is modeled using a Gaussian surface heat source, taking into account the interaction between the laser beam, the workpiece material, and the generated metal-vapor plasma. To validate the simulation model, a large set of experiments was performed for the purpose of comparing the experimental with the simulation results. The experiments were conducted on stainless steel and a pressure vessel steel plate using the DMG MORI Lasertec 40 machine for various combinations of the three machining process parameters: average power, repetition rate, and scanning speed. The experimental results positively validated the simulation model. Τhe numerical results were examined and some conclusions were drawn about the effect of the machining parameters on the laser engraving process. [ABSTRACT FROM AUTHOR]

Flake is an irreparable crack type defect in many huge steel products, especially in heavy forging. Lots of previous studies have revealed that flake is usually originated at cavities within heavy forging. In addition, whether it is generated and what size after it is formed both largely depend on the hydrogen pressure within the cavity. However, the most part of previous studies only related cavity hydrogen pressure to steel hydrogen concentration, and few studies considered the metal forming effect. In this paper, the relationship between cavity hydrogen pressure and metal forming process of heavy forging is addressed from a simulation perspective. Different from previous research, this paper wants to emphasize the importance of metal forming process in the flake formation. There are four parts in this paper. We start with a brief introduction to the flake and the importance of cavity hydrogen pressure in its formation. Then, we propose a cavity hydrogen pressure calculation model. After that, the simulation results and discussions are provided. We end the study with the conclusion. We find in our research that metal forming has a great influence on cavity hydrogen pressure, especially with large deformation. Based on these findings, we may conclude that flake formation not only depends on the steel hydrogen content, but also very depends on the way of forming. Admittedly, what we have discussed in this study is far from complete. And some improvements we want to make in our further research include (1) studying the influence of metal forming on flake formation in micro-scale, such as in grain scale; (2) verifying the simulation results with experiment; and (3) considering the hydrogen diffusion process in metal forming process. [ABSTRACT FROM AUTHOR]

The spreading of high computational resources at very low costs led, over the years, to develop new numerical approaches to simulate the fluid surrounding a sail and to investigate the fluid-structure interaction. Most methods have concentrated on upwind sails, due to the difficulty of implementing downwind sailing configurations that present, usually, the problem of massive flow separation and large displacements of the sail under wind load. For these reasons, the problem of simulating the fluid-structure interaction (FSI) on downwind sails is still subject of intensive investigation. In this paper, a new weak coupled procedure between a RANS solver and a FEM one has been implemented to study the FSI problem in downwind sailing configurations. The proposed approach is based on the progressive increasing of the wind velocity until reaching the design speed. In this way, the structural load is also applied progressively, therefore, overcoming typical convergence difficulties due to the non-linearity of the problem. Simulations have been performed on an all-purpose fractional gennaker. The new proposed method has been also compared with a classic weak FSI approach. Comparable results have been obtained in terms of flying shape of the gennaker and fluid-dynamic loads. The most significant characteristic of the proposed procedure is the easiness to find a solution in a very robust way without convergence problem, and also the capability to reduce the simulation time with regard to the computational cost. [ABSTRACT FROM AUTHOR]

Despite the development of pressurized irrigation systems in the second half of the twentieth century, surface irrigation continues to be the most used system in the world. Computer tools are required to support performance improvements leading to its sustainability. A simulation model of basin/border irrigation is presented in this paper combining two-dimensional overland hydraulics based on Saint-Venant equations with three-dimensional infiltration based on the mixed form of Richards' equation. The coupling of these equations is attained by enforcing continuity of pressure at the soil surface. The model applies a finite-volume approach using the diffusion-wave approximation form of the shallow water equations. Water flow on undulated topographies is simulated using a non-orthogonal curvilinear coordinate system. An underrelaxed-modified Picard iteration algorithm is used for Richards' equation, and an underrelaxed Picard iteration algorithm is used for Saint-Venant equations. The model was validated using experiments from the literature. Model performance was robust and accurate, even in complex theoretical cases with strong soil-surface undulations. Mass conservation was judged satisfactory in all cases, with the long-term ratio of mass balance error in the order of 10−2 in the most complex simulations. Soil type, mesh non-orthogonality, and the interaction of these variables had a strong effect on CPU time. Additional research will be required to transform this simulation model into an operational tool for surface irrigation. Attention will need to be paid to additional surface irrigation systems, soil types, and the optimization of computational speed. [ABSTRACT FROM AUTHOR]

In recent years, tremendous advances have been made in the choice of materials used in the industry. With weight reduction as the goal, composite and polymer materials are more and more popular but they are almost transparent to X-ray. Because of this, interest has grown in other wavelengths like terahertz (THz). Due to a difference in how X-ray and THz propagate, X-ray CT algorithms cannot be directly used. For example, THz induces refraction making the reconstruction problem nonlinear. In this paper, we present a new algorithm which complies with beam profile intensities, refraction, and reflection. It is based on linearizing the reconstruction process around a computer-aided design (CAD) model of the object to be reconstructed. The method we propose computes the deviation between the object and this model. [ABSTRACT FROM AUTHOR]

To overcome the difficulty in forward and inversion problem in complex geological model, including undulated topography and irregular subsurface interface, we in this paper realize a multistage triangular shortest-path method for multi-phase seismic ray tracing and combine a nonlinear inversion solver (damped minimum norm and constrained least squares problem solved by a conjugated gradient method) to simultaneously invert four elastic parameters (or four Thomsen parameters) in anisotropic media using combined direct and reflected arrival times. For trading-off between different parameter updating, we normalize the sensitivity functions (traveltimes derivatives with respect to different elastic (or Thomsen) parameter changes) to balance four updated elastic (or Thomsen) parameters in simultaneous inversion process, due to the magnitude and pattern of partial derivatives more sensitive to different phase slowness angles. In addition, in order to solve the multi-solution problems of qSV-wave inversion, a strategy of multistage inversion is proposed. For testing the efficiency and correctness of proposed inversion method, we use the picked traveltimes in synthetic seismograms as the observed traveltimes in the inversion. The results show that both inverted images by taking the picked traveltimes in synthetic seismograms as the observed data and by taking predicted traveltimes using ray tracing method as observed data have a similar imaging pictures, which verify the efficiency and correctness of the proposed inversion method. Furthermore, the inverted results by normalized kernel functions are better than that of inversion without applying the normalized kernel functions for both qP and qSV data, and the results of the multistage inversion are better than that of the simultaneous inversion without multistage inversion applied in qSV-wave inversion. In addition, both elastic and Thomsen parameter inversions for the same anisotropic model indicate that there are no big differences between the two inverted results even though the sensitivity kernels related to the Thomsen parameters have relatively large values. [ABSTRACT FROM AUTHOR]

Linear accelerators operating at millimeter or sub-terahertz frequencies and short pulse duration have the advantages of lower power consumption and high repetition rate. In this paper planar metallic accelerating structures with different modes operating at 210 GHz were designed. A tolerance study was also carried out to determine the sensitivities of the geometric parameters to the wakefield acceleration performance. The generated Wakefield was simulated using the beam parameter of the Compact Linear Advanced Research Accelerator (CLARA) test facility at Daresbury Laboratory. For a 55 MeV single electron bunch with charge of 250 pC and a bunch length of 0.27 mm (0.9 ps), an equivalent acceleration gradient of 20 MV/m was achieved in the simulation. The relatively modest acceleration gradient was limited by the charge in a single bunch. The acceleration gradient could be further improved by using a bunch train which has larger total bunch charge. From the simulation, the acceleration gradient of 100 MV/m can be generated when it is driven by a 10-bunch beam train. [ABSTRACT FROM AUTHOR]

This paper presents a novel hybrid observer structure to estimate the lateral tire forces and road grip potential without using any tire-road friction model. The observer consists of an Extended Kalman Filter structure, which incorporates the available prior knowledge about the vehicle dynamics, a feedforward Neural Network structure, which is used to estimate the highly nonlinear tire behavior, and a Recursive Least Squares block, which predicts the road grip potential. The proposed observer was evaluated under a wide range of aggressive maneuvers and different road grip conditions using a validated vehicle model, validated tire model, and sensor models in the simulation environment IPG CarMaker®. The results confirm its good and robust performance. [ABSTRACT FROM AUTHOR]

The diversified use of filamentary composites in harsh marine environments, recorded in recent years, has prompted researchers to focus their work on the reliability prediction. Through failure criteria, Tsai-Wu and the maximum stress, the reliability of multilayer tubular structures under mechanical loading is the subject of this paper, where Monte Carlo method estimated the failure probability. A sensitivity analysis was performed in order to identify the influence of the different parameters, such as materials' properties, geometry, manufacturing and loading, on the reliability of the composite cylindrical structure studied. To achieve a high accuracy of the results, we have carried out 105 simulations. The results showed great influence on pressure loading, ply thickness and finally winding angle of filament composite. [ABSTRACT FROM AUTHOR]

This paper presents a metamodel-based constrained optimization method, called Radial basis function-based Constrained Global Optimization (RCGO), to solve optimization problems involving computationally expensive objective function and inequality constraints. RCGO is an extension of the adaptive metamodel-based global optimization (AMGO) algorithm which can handle unconstrained black-box optimization problems. Firstly, a sequential sampling method is implemented to obtain the initial points for building the radial basis function (RBF) approximations to all computational expensive functions while enforcing a feasible solution. Then, an auxiliary objective function subject to the approximate constraints is constructed to determine the next iterative point and further improve the solution. During the process, a distance function with a group of exponents is introduced in the auxiliary function to balance the local exploitation and the global exploration. The RCGO method is tested on a series of benchmark problems, and the results demonstrate that RCGO needs fewer costly evaluations and can be applied for costly constrained problems with all infeasible start points. And the test results on the 30D problems demonstrate that RCGO has advantages in solving the problems. The proposed method is then applied to the design of a cycloid gear pump and desirable results are obtained. [ABSTRACT FROM AUTHOR]

In this paper, we articulate a novel particle-centric method to simulate the dynamics of brittle fracture for anisotropic materials. The key motivation of this paper is to develop a new hybrid, particle-based simulation that inherits advantages from both powerful finite element methods and popular mesh-free methods, while overcoming certain disadvantages of both types of methods. Our method stems from two novel aspects: (1) a physical model built upon an improved mechanical framework and the adaptive smoothed particle hydrodynamics (SPH), an improved variant of traditional SPH, which can handle complicated anisotropic elastic behaviors with little extra cost; and (2) a hybrid, adaptive particle system that serves for more accurate fracture modeling with richer details. At the physical level, in order to facilitate better control during the formation of fracture and improve its time performance, we develop a physical framework based on contact mechanics and adopt the stress and energy analysis on the anisotropic SPH numerical integration to pinpoint fracture generation and propagation. At the geometric level, in order to reduce time consumption and enhance accuracy in rigid dynamics and fracture generation, we employ hybrid, fully adaptive particles in the vicinity of fracture regions via geometric subdivision. Our novel approach can facilitate the user to control the generation of cracks with low computational cost and retain high-fidelity crack details during animation. Our comprehensive experiments demonstrate the controllability, effectiveness, and accuracy of our method when simulating various brittle fracture patterns for anisotropic materials. [ABSTRACT FROM AUTHOR]

The improvement of the simulation process requires an integration of the design and analysis models. There are two essential tasks in the design analysis process: (i) computer-aided design (CAD) which provides the geometric description of the model and (ii) the finite element method (FEM) used for mechanical behaviour simulations. The interoperability between these two tasks reduces costs and improves product quality through the acceleration of design analysis loops. Our activity fits into this research orientation by providing a method to link the FE analysis and the CAD model. This is done by reconstructing the CAD model from the FE analysis results (deformed mesh). This paper proposes a method to update the CAD geometry from the deformed mesh. This approach allows for rebuilding the CAD model after analysis by extracting geometric information from the deformed mesh. An illustration of the developed method is discussed at the end of this paper. [ABSTRACT FROM AUTHOR]

This research paper presents the development of a geometrical torque prediction method (GTPM), which could be used to determine relative torque values for tapping processes with various tapping tools and diameters. Experimental tests and three-dimensional finite element method (FEM) simulations were carried out using four different tap tools that are frequently used in practice. A segmented workpiece model, which could significantly reduce the computing time of the FEM tapping simulations, was validated by comparing the results to the experimentally obtained data. The determined relative torque values show a parabolic progression with rising tool diameter, which is the reason why the GTPM could be developed on this basis, to further reduce the high computing time and optimize the tool design process without the production of costly prototypes. To verify the developed GTPM, the according predicted relative torque values were compared to the previously carried out simulations and experiments, showing a good agreement. A FEM software module was created to implement the developed methods in an interactive and automated way, providing an efficient method to improve the tapping tool development process. [ABSTRACT FROM AUTHOR]

This paper presents the design, simulation and fabrication of LTCC-based isothermally interconnected microhotplate. A thermal electric finite element analysis is used to examine the electro-thermo-mechanical behaviour of microhotplate. The heating element is platinum having resistivity 100 mΩ/sq and LTCC is the base substrate. The simulation has been performed for different thicknesses of LTCC substrate. The fabrication has been carried out for 0.711 mm thick LTCC substrate. The comparison between simulation results and characteristics of fabricated microhotplate on 0.711 mm thick LTCC substrate has been made. The variation in temperature of simulated and fabricated microhotplates has been analyzed with respect to the applied voltages. [ABSTRACT FROM AUTHOR]

In this paper, a diaphragm based MEMS capacitive pressure sensor array in conjunction with signal conditioning circuitry is designed for measuring Heart Rate (HR) of human being. In order to measure the heart rate, an array of capacitive sensors are mounted on wrist in such a way that the radial artery blood flow during contraction and expansion of the heart, impinges on the sensor diaphragms. Due to blood flow in the wrist artery, the designed circular diaphragm of the sensor is being deflected and thus induces a corresponding change in the original capacitance value. A proposed schematic of the system to measure the change in capacitance consists of signal conditioning circuitry along with the sensors. The structure of the sensor consists of parallel plates having 1.5 micron air gap in between. This change in capacitance is detected by a CMOS based capacitance-to-voltage converter which is designed as a precision interface with the sensor array. The designed MEMS sensor has a Poly Silicon diaphragm and is capable of identifying HR (60-100 bpm) which corresponds to a specific change in absolute pressure from 10 to 100 kPa for 5 micron thick diaphragm with 3600 µm area. The design of the sensor along with its fabrication steps and characteristics analysis are performed in FEM based simulation software. [ABSTRACT FROM AUTHOR]

With the emergence of advanced high strength steels (AHSSs) and other light-weight materials, edge fracture has been one of the important issues evading reliable prediction using CAE tools. To study edge fracture behavior of AHSS, a comprehensive hole expansion test (HET) program has been carried out on a DP780 sheet. Specimen with three different edge conditions (milled edge, water jet cut edge and punched edge) are manufactured and tested. Results reveal that the hole expansion ratio (HER) of the present DP780 sheet is around 38 % for milled specimen and water jet cut specimen, and about 14 % for punched specimen. A novel method of a central hole specimen tension is also introduced for edge fracture study, showing a similar trend as found in HET. The paper briefly presents a procedure and the results for a full calibration of the DP780 sheet for plasticity and fracture, where a hybrid testing/simulation method is used to obtain parameters for Hill 48 plasticity model and modified Mohr-Coulomb fracture model. The finite element simulation gives an accurate prediction of HER, as well as the load displacement response and specimen deflection distribution in the hole expansion tests on uncracked material. The correlation between simulation and tests on central hole specimen also turns out to be very good. The paper also presents a very interesting insight of the initiation and propagation of cracks from the hole edge during a hole expansion test by numerical simulation in comparison with testing observation. The number of final cracks are accurately predicted. Other new aspects of the present paper include an improved 3D DIC measurement technique and a simplified analytical solution, from which a rapid estimation of displacement and hoop strain field can be made (see 'Appendix 2'). [ABSTRACT FROM AUTHOR]

Studying human motion using musculoskeletal models is a common practice in the field of biomechanics. By using such models, recorded subject's motions can be analyzed in successive steps from kinematics and dynamics to muscle control. However simulating muscle deformation and interaction is not possible, but other methods such as a finite element (FE) simulation are very well suited to simulate deformation and interaction of objects. In this paper we present a practical framework for the automatic generation of FE ready meshes based on subject-specific segmented MRI data. The proposed method resolves several types of data inconsistencies: noise, an incomplete data set and self-intersections. This paper shows the different steps of the method, such as solving overlaps in the segmented surfaces, generating the volume mesh and the connection to a musculoskeletal simulation. [ABSTRACT FROM AUTHOR]

In this paper, we propose multilevel Monte Carlo (MLMC) methods that use ensemble level mixed multiscale methods in the simulations of multiphase flow and transport. The contribution of this paper is twofold: (1) a design of ensemble level mixed multiscale finite element methods and (2) a novel use of mixed multiscale finite element methods within multilevel Monte Carlo techniques to speed up the computations. The main idea of ensemble level multiscale methods is to construct local multiscale basis functions that can be used for any member of the ensemble. In this paper, we consider two ensemble level mixed multiscale finite element methods: (1) the no-local-solve-online ensemble level method (NLSO); and (2) the local-solve-online ensemble level method (LSO). The first approach was proposed in Aarnes and Efendiev (SIAM J. Sci. Comput. 30(5):2319-2339, 2008) while the second approach is new. Both mixed multiscale methods use a number of snapshots of the permeability media in generating multiscale basis functions. As a result, in the off-line stage, we construct multiple basis functions for each coarse region where basis functions correspond to different realizations. In the no-local-solve-online ensemble level method, one uses the whole set of precomputed basis functions to approximate the solution for an arbitrary realization. In the local-solve-online ensemble level method, one uses the precomputed functions to construct a multiscale basis for a particular realization. With this basis, the solution corresponding to this particular realization is approximated in LSO mixed multiscale finite element method (MsFEM). In both approaches, the accuracy of the method is related to the number of snapshots computed based on different realizations that one uses to precompute a multiscale basis. In this paper, ensemble level multiscale methods are used in multilevel Monte Carlo methods (Giles 2008a, Oper.Res. 56(3):607-617, b). In multilevel Monte Carlo methods, more accurate (and expensive) forward simulations are run with fewer samples, while less accurate (and inexpensive) forward simulations are run with a larger number of samples. Selecting the number of expensive and inexpensive simulations based on the number of coarse degrees of freedom, one can show that MLMC methods can provide better accuracy at the same cost as Monte Carlo (MC) methods. The main objective of the paper is twofold. First, we would like to compare NLSO and LSO mixed MsFEMs. Further, we use both approaches in the context of MLMC to speedup MC calculations. [ABSTRACT FROM AUTHOR]

Grinding is regarded as a special multiple edge cutting process, in which the abrasive grains remove the workpiece material at the microlevel. The grain-workpiece interaction, which resembles the microcutting process, directly modifies the workpiece surface and dominates all the output measures of grinding process. Recently, a virtual single-layer cubic boron nitride (CBN) grinding wheel model is developed by simulating each wheel fabrication step, which makes the estimation of the single grain material removal mode possible in grinding. Therefore, the study of the grain-workpiece interaction through microcutting behavior on the abrasive grains becomes necessary for the quantitative investigation of grinding processes. In this paper, the influence of the grain orientation on the microcutting performance of CBN grains is studied through finite element method (FEM) simulation based on response surface methodology (RSM). The FEM simulation helps in both qualitative and quantitative understanding of microcutting process. And the RSM analysis is proved to be an effective tool for factorial analysis in this paper. The results indicate that the single grain microcutting force is sensitive to the grain wear condition and orientation status, and there exists preferable orientation condition for microcutting with abrasive grains to achieve minimum cutting force. [ABSTRACT FROM AUTHOR]

This paper deals with the mathematical modelling of confinement of paralic ecosystems. It is based on the recent paper (Frénod and Goubert in Ecol. Model. 200(1-2):139-148, ) that presents a modelling procedure in order to compute the confinement field of a lagoon. Here, we improve the existing model in order to account for tide oscillations in any kind of geometry such as non-rectangular lagoons with a non-flat bottom. The new model, that relies on PDEs rather than ODEs, is then implemented thanks to the finite element method. Numerical results confirm the feasibility of confinement studies thanks to the introduced model. [ABSTRACT FROM AUTHOR]

To understand the stress evolution and failure mechanisms of thermal barrier coatings (TBCs), finite element simulations are an invaluable tool. Simulations are especially useful to unwrap complex interactions of different phenomena at high temperature, including creep, sintering, diffusion, and oxidation. However, the correct setup and evaluation of a finite element model for this problem are difficult. This article reviews critical issues in modelling TBC systems. Some of the most important aspects are as follows: (a) stresses in 3D simulations may differ considerably from 2D models; (b) the interface shape strongly affects the stresses and using an idealized geometry may underestimate stresses; (c) crack propagation requires simulating sufficiently large regions to correctly capture stress redistribution; (d) a correct description of the material behaviour (visco-plasticity, TGO growth, sintering) is crucial in determining the stress state. The article discusses these and other issues in detail and provides guidelines on the choice of model parameters, boundary conditions, etc. The paper also points out open questions in modelling TBC systems and discusses aspects of verification and validation. [ABSTRACT FROM AUTHOR]

In this paper, a simulation model for two-roll cross wedge rolling (CWR) was presented to investigate the deformation mechanism for forming shafts without concavity by using the finite element method. Based on the simulation results, the reason for concavity in both sides of the rolled piece in the CWR process was analyzed in detail, and a method to implement the CWR process without loss of material was brought forward by billet compensation. In addition, the influence of the main process parameters on the concavity depth of the workpiece with a tapered or circular-arc end was compared and ascertained. The study results show that the concavity depth is in direct proportion to the cone angle, but in inverse proportion to the central angle, and the concavity can be improved with larger area reduction and mill length under the two profiled ends. Subsequently, the feasibility of using profiled billets to effectively control the concavity was verified via the rolling experiments. [ABSTRACT FROM AUTHOR]

In this paper, we firstly discussed the principle and deformation characteristic of axial-pushed incremental rolling process of spline shaft, and then, an axial-pushed incremental warm rolling process of spline shaft with 42CrMo steel is introduced and studied to investigate the formation mechanism and analyze the effects of process parameters. In order to improve the accuracy of finite element simulation, the plastic flow behavior and constitutive characteristic of 42CrMo steel during warm forming process are studied through the isothermal warm compression tests, and then, the microstructure of tempered sorbite and high-accuracy constitutive equations of 42CrMo steel are obtained. Next, the effects of die angle and deformation temperature on forming load and tooth-filled quality during axial-pushed incremental warm rolling process are analyzed based on finite element analysis (FEA). The optimum die angle of the entrance section and warm forming temperature are determined as 8 and 700 °C, respectively. To verify the results of simulation, the corresponding experiments are carried out on the warm rolling equipment, which is designed by the authors. Finally, the relevant improvement by tooth divided flow method (TDFM) is raised to eliminate the negative effect of blank diameter on this process. [ABSTRACT FROM AUTHOR]

This paper is devoted to monolithic modeling of piezoelectric energy harvesting devices. From a modeling perspective, piezoelectric energy harvesting is a strongly coupled phenomenon with two-way coupling between the electromechanical effect of the piezoelectric material and the harvesting circuit. Even in applications related to shunt damping, where the attached electrical circuit is passive, accurate modeling of the strong coupling is crucial for proper evaluation of the relevant parameters. The article proposes a monolithic mixed-hybrid finite element formulation for the predictive modeling and simulation of piezoelectric energy harvesting devices. The governing equations of the coupled electromechanical problem are converted into a single integral form with six independent unknown fields. Such a holistic approach provides consistent solution to the coupled field equations which involve structural dynamics, electromechanical effect of the piezoelectric patches and the dynamics of the attached harvesting circuit. This allows accurate computation of the eigenvalues and corresponding mode shapes of a harvester for any finite resistive load coupled to the harvester. The fully three-dimensional mixed-hybrid formulation is capable of analyzing structures with non-uniform geometry and varying material properties. The results of the finite element model are verified against the analytical results of a bimorph harvester with tip mass reported in the literature. [ABSTRACT FROM AUTHOR]

Twin-wire welding based additive manufacturing (TWAM) is a novel additive manufacturing (AM) process for creating metallic objects using gas metal arc welding (GMAW). The twin-wire welding, apart from offering higher deposition rates, also makes it possible to create gradient objects by the use of dissimilar filler wires. However, there is necessity to manage the thermal stresses while depositing multiple layers on the substrate plate; this is one of the major challenges to be addressed. With the help of finite element analysis (FEA) and experimental methods, this paper studies the effect of area-filling paths on the residual stresses developed during weld-deposition. Three area-filling patterns viz. raster, spiral-in, and spiral-out were chosen. FEA for these three patterns was done using ANSYS Mechanical APDL. The twin-wire arc weld-deposition was modeled as a set of two moving heat sources separated at a fixed distance. The deposited material was activated by element birth method once the arc passes over a location, simulating the weld material deposition. The temperature gradient induced residual stresses produced during and post material deposition was predicted using passively coupled thermo-mechanical simulations. For validation, the weld-deposition experiments were done using twin-wire GMAW welding set up, and residual stresses were measured using an X-ray diffraction (XRD) system. Temperature distribution plays a critical role in the evolution of the residual stresses during weld-deposition. Hence, two metrics viz., thermal mismatch profile, and secant-temperature rate were introduced to quantify preheat and conduction. It was observed that raster patterns had the lowest thermal mismatch and secant rates resulting in the lowest residual stresses of the three area-fill patterns. Residual stresses from experiments has reasonable correlation with those obtained from elastic-FE simulations in order as well as trend and provide valuable insights into the evolution of the stresses for various area-fill patterns in TWAM. [ABSTRACT FROM AUTHOR]

Shot peening is a mechanical surface treatment widely used in the automotive and aerospace industries to improve the fatigue performance of metallic parts. This treatment extends the fatigue life by (i) retarding the crack growth due to the induced compressive residual stresses and (ii) inhibiting the crack initiation through the surface work hardening. However, the effect of shot peening on the fatigue performance is mainly influenced by the choice of the process's parameters. The aim of this research paper is to propose a simple methodology for optimizing the shot-peening surface's process parameters taking into account the redistribution of the initial shot-peening properties after cyclic loading. For this purpose, the response surface methodology coupled with finite element analysis is implemented. Moreover, the effects of shot velocity, shot diameter, and peening coverage (duration of treatment) and their interactions on the fatigue performance of shot-peened parts subjected to cyclic loadings are discussed. This analysis can be considered as a very helpful tool for designer engineers in shot-peening parameter optimization. [ABSTRACT FROM AUTHOR]

An electrical response of a microflow sensor would open a wide horizon of uses and should intensify the integration of MEMS (Micro-Electro-Mechanical-System) microfluidic-based LOC (Lab-On-Chip). This paper presents an original microflow sensor which will be able to measure a low fluid flow rate. The sensor is designed and optimized using a multiphysics modelling and FEM (Finite Element Method) simulations implemented on Comsol Multiphysics software. The sensing element made of CPDMS (Conductive PolyDiMethylSiloxane) consists in microbridge suspended into PDMS microchannel. The microbridge acts as a transducer. It converts the mechanical bending due to a fluid flow to an electrical signal using the piezoresistive property of the CPDMS. The numerical simulation results show that under specific geometrical parameters, the sensor has a sensitivity of 0.12 % ml min for low flow rates. Furthermore, the simulation results also show that the laminar aspect of the flow is maintained and to avoid the strangling effect, a good equilibrium must be achieved between the microchannel height and the desired range of the microbridge dimensions. This work opens a horizon for microfluidic devices to measure a low flow rate using a piezoresistive effect giving access to an electrical response. [ABSTRACT FROM AUTHOR]

In this paper, the industrial hammer peening process is optimized using multi-objective, sequential approximate optimization, which is a mathematics- plus finite element- based algorithm. Since the number of design and objective variables is significant, the global optimization problem is split into two, more manageable multi-objective subproblems. The use of surrogate modelling together with an intensification and diversification strategy for solving the optimization subproblems allows for significant computational cost savings without loss of accuracy. Additionally, we propose a Bayesian inference criterion-based sensitivity approach for 'filtering-out' design variables which do not significantly affect objectives variables. Finally, guidelines for selecting appropriate Pareto optima are given using $N-1$ Pareto diagrams, where N is the number of objective variables. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive approach developed to design an effective prediction model for hardness profile in laser surface transformation hardening process. Based on finite element method and Artificial neural networks, the proposed approach is built progressively by (i) examining the laser hardening parameters and conditions known to have an influence on the hardened surface attributes through a structured experimental investigation, (ii) investigating the laser hardening parameters effects on the hardness profile through extensive 3D modeling and simulation efforts and (ii) integrating the hardening process parameters via neural network model for hardness profile prediction. The experimental validation conducted on AISI4340 steel using a commercial 3 kW Nd:Yag laser, confirm the feasibility and efficiency of the proposed approach leading to an accurate and reliable hardness profile prediction model. With a maximum relative error of about 10 % under various practical conditions, the predictive model can be considered as effective especially in the case of a relatively complex system such as laser surface transformation hardening process. [ABSTRACT FROM AUTHOR]

Subsurface stresses in welded structures increase the likelihood of fatigue cracks and environmental induced material degradation. The ability to evaluate stresses at the surface as well as in the interior of welded structural members would substantially increase the accuracy of structure life estimation. The longitudinal critically refracted ( L) wave is a bulk longitudinal mode that travels within an effective depth underneath the surface. It may be used to detect in-plane subsurface stresses in the structures. This paper presents a three dimensional thermo-mechanical analysis to evaluate welding residual stresses in dissimilar plate-plate joint of AISI stainless steel 304 and Carbon Steel A106-B type. After finite element simulation, the residual stresses were evaluated by L ultrasonic waves. Finally the results of two methods were compared and verified by hole-drilling method. This paper introduces a combination of 'Finite Element Welding Simulation' and 'Ultrasonic Stress Measurement using the L Wave' which is called as ' FEL'. The capabilities of FEL″. The capabilities of FEL in residual stress measurement are confirmed here. And also this paper evaluates residual stresses of dissimilar welded joints by LCR ultrasonic waves. It has been shown that predicted residual stress from three dimensional FE analyses is in reasonable agreement with measured residual stress from LCR method and also the results of both are verified with hole-drilling experimental measurements. [ABSTRACT FROM AUTHOR]

An appropriate assessment of the dynamic behavior of marine propulsion shaft in ships is essential to enable optional delivery of power to the propeller and to minimize unnecessary vibration. Various vibrations coupling with each other can significantly influence the dynamical behavior of the shaft and threaten the reliability of ships. This paper presents a finite element analysis model with multiple constraint conditions to analyze the coupled transverse and longitudinal vibrations of a marine propulsion shaft. Based on this model, in addition to the coupled natural frequencies of each direction, the maximum acceleration are also determined. Furthermore, the simulation of an idling and loading vibration analysis is discussed and validated against experimental results, over a range of rotational speeds. The output of numerical simulation is found to agree with the corresponding results from experimental tests. Finally, an accurate and applicative FEA model for coupled transverse-longitudinal vibration of shaft has been obtained. [ABSTRACT FROM AUTHOR]

In order to achieve efficiently the optimal design and evaluation of PDC (polycrystalline diamond compact) bit, a finite element model for PDC bit cutting rock was established, forecasting the torque and the drilling pressure distribution trends of the cutting teeth on the bit. Through the PDC bit drilling rock, our experimental model validates the reasonableness and effectiveness of finite element simulation. It further demonstrates that the results of the changing trend of experiment and finite element simulation are very close and verify the accuracy and feasibility of the simulation model. The finite element model for single wing PDC cutting rock was established. This paper analyzes the distribution trends of the cutter torque and drilling pressure on bit under the conditions of the different penetration rates and rotational speeds. The 'attack' of the cutting teeth is also analyzed. The results show that the torque of the cutting teeth is increased with the increasing penetration rate with the other conditions being the same. Under the same penetration rate and rotating speed, the drilling pressure of the cutting teeth tends to increase first with the increasing distance from the center axis of the drill bit, and then decrease. The cutting force of each tooth increases with the increasing penetration rate, and near the shoulder, it reaches the maximum, even though the cutting force is less affected by the rotating speed. [ABSTRACT FROM AUTHOR]

Classical strength criteria, like the von Mises criterion, are used to postulate the failure of ductile materials like steel or brass. It is known that for the application of foams in modern lightweight structures extended criteria are required, since foams are sensitive to hydrostatic stress. This observation on the macroscale can be explained by the deformation mechanisms of one single foam cell. Under hydrostatic stress, the deformation of the cell causes a non-uniform stress state of the cell walls. To understand the mechanism on the microlevel, a finite element model on the basis of a tetrakaidecahedron as unit cell was implemented. Utilising a strain energy-based homogenisation concept, the effective properties of the foam can be obtained. To adapt the geometric properties of the model to the real microstructure of the foam, results of a computer tomography image analysis were used by considering several imperfections in the cell geometry. For the analysis of the stress state on the microlevel, different load cases were applied to the unit cell. By means of these simulations, the geometrically nonlinear stress-strain curves on the macrolevel were deduced. Furthermore, the analysis of the finite element model provides an insight into the deformation mechanism on the microscale and allows the prediction of failure as well. Finally, the predicted failure points are represented in the Burzyński plane and compared with experimental results. The current paper focuses on the hard foam ROHACELL $${^{\circledR}}$$ IG-series (industrial grade), which is a closed-cell PMI foam produced by Evonik Industries AG, Germany. [ABSTRACT FROM AUTHOR]

Ploughing force is a parasitic force induced by the blunt cutting edge and the contact at flank face. Investigation on the ploughing force is necessary for the cutting mechanism understanding, the tool wear monitoring, and the tool sharpness evaluation. In this paper, a new comparison method to determine the ploughing force is developed by considering the cutting edge radius. This method is verified in the FEM simulation. Cutting experiments are performed to investigate the ploughing force in microcutting. Not only the cutting edge radius but also the uncut chip thickness is found to have great effects on the ploughing force. The nonlinear increase of the total specific cutting energy is also attributed to the ploughing force. [ABSTRACT FROM AUTHOR]

The paper discusses finite element (FE) modeling for predicting structural damage and correlation studies of dynamic responses in rotorcraft composite structures under high energy bird impact. Before these applications of numerical modeling techniques the simulations are to be accepted by the industry for design development and certification of composite aircraft structures, composites damage models have to be developed and implemented in commercial FE codes, and validation studies at specimen and substructure level have to be performed. Since the experimental tests are expensive and difficult to perform, numerical simulations can only provide significant help in designing high-efficiency bird-proof structures. The design concept is based on the absorption of the major portion of the bird kinetic energy by the composite skins, in order to protect the inner honeycomb core from damage, thus preserving the end plate functionality for safe landing. To this purpose, the end plate skin is fabricated from composite layers, which unfold under the impact load and increase the energy absorption capability. The numerical modeling of bird strike using the Lagrangian approach and smooth particle hydrodynamics formulation and the critical design parameters are considered in carrying out the analysis. A numerical model of this problem has been developed with an explicit finite element code Autodyn. Analysis is carried out for the developed model using the test parameters. Numerical results by means of bird modeling approaches and accurate simulations of composite structures phenomena during impact are substantiated with experimental test results. The results obtained from the analysis and test shows close conformity implying their appropriateness in the simulation of bird strike. [ABSTRACT FROM AUTHOR]

Prediction of forces in cutting operations is a valuable asset to manufacturers. This paper demonstrates the improvements in force prediction achievable in finite element simulations of orthogonal cutting with the incorporation of temperature-dependent friction data obtained from a custom heavy-load, high-temperature tribometer. The tribometer employed is briefly described and its similarities to tool-chip contact in cutting discussed. Simulations with the temperature-dependent friction data were performed over a range of uncut chip thickness, cutting speed, and tool flank wear conditions. For comparison sake, select simulations were also run using a constant friction coefficient model and all simulation results were validated against experimentally obtained force measurements. The temperature-dependent friction data simulations capture the experimental trends in force with respect to all three of the parameters investigated. For unworn tools, the simulations tend to slightly overestimate the tangential and feed force components. For worn tool profiles, the simulations predicted forces with minimal error for most scenarios, overestimating the tangential force and underestimating the feed force. Comparison of simulated temperatures with the range of those for which experimental material properties were obtained, particularly friction coefficients, is proposed as a useful check as to whether simulation results can be reasonably trusted. [ABSTRACT FROM AUTHOR]

In spite of the development of automated tolerance inspection systems for manufactured parts over the years, there are still processes that inevitably require manual intervention making full automation impossible in most cases; in particular when dealing with deformable parts. In most current industrial inspection systems, a deformable part under inspection must first be mechanically constrained on a rigid support or jig so as to be able to compare it with its nominal shape. This paper presents a new system to perform real-time surface inspection of deformable parts that does not require fixturing. Instead, the proposed system applies virtual forces to the part's CAD model as if the part was installed in the fixturing device. Normally, a precise finite element method (FEM) simulation should be used to approximate the deformation that appends when the part is installed in the device. Even with a fast parallel computer, FEM is far from being real-time and cannot be used for on-line inspection. In the proposed system, a radial basis function approximation of the FEM simulation is trained off-line and used to speed-up the simulation by an order of magnitude. Experimental evaluation of the proposed system is presented for three plastic parts. Using the proposed scheme, an approximation of 0.25 mm compared with the real deformation was obtained. In this paper, statistical results are presented such as the average deviation, standard deviation, and processing time between the approximations obtained with the proposed method and with the finite element method applied to the full CAD model. [ABSTRACT FROM AUTHOR]

This paper describes an investigation of a high-strength concrete frame reinforced with high-strength rebars that was tested in the structure engineering laboratory at Shenyang Jianzhu University. The frame specimen was pseudodynamically loaded to indicate three earthquake ground motions of different hazard levels, after which the test specimen was subjected to a pseudo-static loading. This paper focuses on the design, construction and experiment of the test frame and validation of the simulation models. Research shows that a high-strength concrete frame reinforced with high-strength rebars is more efficient and economical than a traditional reinforced concrete frame structure. In addition to the economies achieved by effective use of materials, research shows that the frame can provide enough strength to exceed conventional reinforced concrete frames and provide acceptable ductility. The test study provides evidence to validate the performance of a high-strength concrete frame designed according to current seismic code provisions. Based on previous test research, a nonlinear FEM analysis is completed by using OpenSees software. The dynamic responses of the frame structure are numerically analyzed. The results of the numerical simulation show that the model can calculate the seismic responses of the frame by OpenSees. At the same time, the test provides additional opportunities to validate the performance of the simulation models. [ABSTRACT FROM AUTHOR]

The influences of cutting parameters on temperature, stress, and shear angle during dry hard orthogonal cutting (DHOC) of D2 tool steel (62 ± 1 HRC) are investigated in this paper. Temperature and stress are considered the most important aspects to be taken into account in dry hard machining; however, dry hard machining is a complex process, and the temperature fields and residual stress are the most difficult to be measured. Up to now, only very few studies have been reported on influences of cutting parameters on shear angle, temperature, and stress of AISI D2 tool steel (62 ± 1 HRC). In this paper, the Johnson-Cook model is utilized to propose a finite element (FE) model. The FE model is properly calibrated by means of an iterative procedure based on the comparison between experimental resultant forces obtained from literatures and simulated resultant forces. At last, this FE model is utilized to predict the influences of cutting speed and depth of cut on temperature fields and residual stress within a workpiece, cutting tool edge temperature, and shear angle during DHOC hardened AISI D2 tool steel (62 ± 1 HRC) and validated by experimental results. As shown in this investigation, it is also possible to properly analyze the influences of cutting parameters on the cutting mechanism for industrial application. [ABSTRACT FROM AUTHOR]

Abstract  The paper presents a combined noise and damping analysis for MEMS structures, based on frequency-dependent behavioral models extracted from finite element simulations. The design of high sensitivity MEMS-based microsystems needs to consider the frequency noise shaping induced by damping phenomena on micro scale motion, for its contribution can be significant in the system level noise analysis. Frequency-dependent behavioral models for squeeze-film damping are generated from finite element analysis simulations. Unlike existing noise analysis reported in literature, based on frequency-independent damping assumption, the paper integrates the damping and noise aspects using the same frequency-dependent models. The results can be used for a noise-based optimization procedure applied to the design of resonating microsensors, as illustrated for the case of a MEMS-based gyroscope. [ABSTRACT FROM AUTHOR]

The response of a structure to medium-frequency vibrations is highly dependent on several phenomena. One of these, the behavior of joints between substructures, is essential because it controls the distribution of the power injected into the structure and governs most of the dissipative effects. This paper introduces a new method for the identification of joint parameters from experimental vibration data, inspired by previous works on finite element model updating using the error in the constitutive relation. Since such numerical techniques are not suitable for the medium-frequency range, in which the finite element mesh must be refined, our work uses the numerical framework of the variational theory of complex rays, which is a Trefftz approach entirely dedicated to the calculation of medium-frequency vibrations at very low cost. The main scope of this paper is the presentation of the formulation and its validation against actual and numerically-simulated experimental results. [ABSTRACT FROM AUTHOR]