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Prosthesis has been advancing since the day of its introduction, having a tremendous degree of advancement and examination in clinical field as well as in robotics. This has been an influence for researchers who made it conceivable with various types of prosthetics that are accessible these days in the market both commercially and uniquely crafted. This paper throws light on numerical simulation and design of a prosthetic leg. The work focuses on the optimization and simulation of a prosthetic leg, improving its strength and making it cost effective. The paper has described the design and analysis of two early-existed models of prosthetic leg, comparing their strength and durability through different material analysis and thereafter designing a new model with better strength, having a high deformation rate or durability, and having much cost-efficient design and material. The Finite element analysis (FEA) was done in Ansys software, the material properties and cost efficiency were kept in mind during the analysis as well as during selection of material. Prosthetics are modified for every person, remembering the utilization and actual properties. In any case, the conventional prosthetics are heavier, and the production is costly andtedious. The current study resolves this issue and proposes an elective plan for prosthetic legs. The designed prosthetic was simulated properly and has been compared with earlier existed models. The study concludes that the new design is much more efficient and user friendly that the wearer will feel comfortable, to live a normal life. [ABSTRACT FROM AUTHOR]

This paper is tackling the elbows bending process using hot mandrels. Through this process the pipe is pushed over a fix or mobile mandrel, which defines the expansion and the radius of curvature and is very important that mandrel deformation to be minimum. The paper presents the finite element model developed for the process described above, the optimization of tool parameters used to obtain and validate the simulation conditions in order to evaluate the effect of different materials on mandrels performances. The numerical simulation analyses were carried out by finite element analysis software NASTRAN and LS-DYNA which has a vast array of capabilities to simulate extreme deformation problems. Results obtained following the manufacturing process FEM simulation optimization are expected to reduce the mandrel production and exploitation costs. [ABSTRACT FROM AUTHOR]

The automobile contains several very important parts, one of which is the friction clutch. Its importance comes from being it is a mechanical coupling device that plays the role of connecting and transmitting the torque generated in the engine to the gear set in the gearbox. The friction material is an important parameter due to withstand the mechanical and thermal load generated in the clutch system. This paper focused on studying the thermal behavior of four different friction lining materials (LUK, Tiger, G95, and HCC) to identify the temperature distribution for each material separately and then compare these materials to arrive at the best material that you can choose in the dry clutch design. Modeling of the model was done by the method of finite element and with the help of the ANSYS program to perform numerical simulations and show results. It may be determined that the thermoelastic behavior of the clutch is influenced by the type of frictional lining material used. After comparing the data, it was discovered that the materials (HCC and G95) were vulnerable to clutch activation for long periods. In the current investigation, the lining materials stood out because they demonstrated a high thermal efficiency when compared to the other materials in the prior study. [ABSTRACT FROM AUTHOR]

The paper presents the finite element modeling of the spatial heat transfer to identify the temperature and the heat flux distributions both in the linear and point thermal bridges in various up-to-date wall systems. The paper considers the spatial heat transfer in the corner zone of the brickwork fragment. The ANSYS finite element program is used for the numerical simulation of the temperature fields and thermal fluxes for the brickwork connection with a hollow-core slab and a balcony slab. The influence of hollow cores in the floor slab is considered in relation to the temperature behavior along the inner surface of the brickwork fragment. To eliminate the negative effect from thermal bridging, it is suggested to increase the temperature on this inner surface. The brickwork thermal properties are investigated herein. [ABSTRACT FROM AUTHOR]

The article is devoted to the method of estimation of the effective mechanical properties of rocks by performing numerical calculations on the digital model of core. The digital model of core is constructed in the form of structured hexahedral grid based on CT scan data. In the representative volume element (RVE) of the core sample, a number of boundary value problems of the elasticity theory with various boundary conditions are solved. The pre-loading of the rock caused by pore pressure is also taken into account. The elasticity problems are solved numerically with the help of finite element method using CAE Fidesys. The results of the solution of each problem are averaged over the volume. Effective properties of core are estimated in the form of the generalized Hooke's law. The paper presents the results of calculations carried out at variable pressure for core made by one (sandstone) and several (pyrite, solid and solid calcite) minerals. It is shown that the dependence of the estimated elastic moduli on the pore pressure is linear. [ABSTRACT FROM AUTHOR]

The aim of this paper is to formulate a new concept of Discrete Element Method (DEM) dedicated to solid body mechanics. The new method is to be an answer to the disadvantages of the classic DEM, which are evident in computer simulations of small solid body objects but less important in the case of rock or powder mechanics. The creation of a computer code implementing the new algorithms is an integral part of the research. The paper presents the basic assumptions of the new method but omits implementation details. At the time of writing, the computer program has been in its pre-alpha phase and no results of computer simulations have been available. The proposed version of the method has been named DEM D+. [ABSTRACT FROM AUTHOR]

This paper concentrates on selected aspects of numerical modeling of a short span thin-walled beams. The performed numerical simulations cover different types of finite elements (shell or solid finite elements) and different mesh sizes. Moreover the shape and magnitude of an initial geometrical imperfection is also investigated. The numerical analysis were made with the Newton-Raphson procedure with geometrical and material nonlinearity. The numerical results were compared with the laboratory four point bending test of a thin-walled beam. Furthermore, some guidelines for numerical simulations of a short span thin-walled beams in bending were proposed by authors. [ABSTRACT FROM AUTHOR]

This paper deals with the simulation of UNS A92024 aluminium alloy cutting processes. In particular, 2D and 3D Finite Element Method (FEM) simulations were carried out in order to estimate cutting forces and chip morphology during turning operations. The material is modelled with two different set of parameters for the Johnson-Cook's (J-C) constitutive equation and a failure Cockroft and Latham's model exploited considers damage. The comparison between the predicted chip morphology and principal cutting forces at varying of J-C parameters and cutting regimes with those experimentally found are presented and discussed. The paper shows the importance of damage criterion in the cutting forces, during the simulation, especially in 3D. [ABSTRACT FROM AUTHOR]

Computer simulation is widely used in the design and development of technical products. Multiscale nature of deformation and fracture of novel materials requires to use for this purpose not only the conventional finite element method but particle methods at different spatial scales as well. This paper presents a computer code aimed for discrete-continuum simulation of friction based on coupling finite elements (as a continuum method) with movable cellular automata (discrete particle method). Two computer codes based on finite elements and written in different programming languages are used: commercial and in-house. Peculiarities of the application program interfaces of the particle code for coupling with both finite element codes are described and analyzed. It is shown that the code developed takes the advantages of both cases and promises to be very efficient for simulating various contact problems including friction. [ABSTRACT FROM AUTHOR]

Bio-heat transfer deals with the heat transfer in the biological bodies. Human skin burn can be analyzed using the Pennes bio-heat equation which has been adopted in many commercial finite element software. Human skin burn also known as thermal burn can result from direct contact with heated object such as a hot disk, hot fluid or being exposed to radiation. Depending upon the condition and duration of exposure thermal burn may cause severe skin damage. In this paper, the three dimensional Finite Element (FE) models of human skin is developed. The burn effect on human skin under the contact with hot object or hot fluid has been analyzed. The radiation effect of a hot object on the skin burn has also been analyzed. The commercial numerical software COMSOL Multiphysics® is used for the purpose. The burn intensity in terms of degree of burn is measured with different burning conditions. The results from this analysis can be used in treatment of burn injuries. [ABSTRACT FROM AUTHOR]

The paper presents a practical implementation of hybrid simulation using Real Time Finite Element Method (RTFEM). Hybrid simulation is a technique for investigating dynamic material and structural properties of mechanical systems by performing numerical analysis and experiment at the same time. It applies to mechanical systems with elements too difficult or impossible to model numerically. These elements are tested experimentally, while the rest of the system is simulated numerically. Data between the experiment and numerical simulation are exchanged in real time. Authors use Finite Element Method to perform the numerical simulation. The following paper presents the general algorithm for hybrid simulation using RTFEM and possible improvements of the algorithm for computation time reduction developed by the authors. The paper focuses on practical implementation of presented methods, which involves testing of a mountain bicycle frame, where the shock absorber is tested experimentally while the rest of the frame is simulated numerically. [ABSTRACT FROM AUTHOR]

The analysis of the interpolation error is particularly important for the error analysis of the finite element methods. In the previous paper, we proved that the finite element solution converges to an exact solution if the maximum circumradius of the triangular elements converges to zero. We call such situation "circumradius condition" and claimed that the circumradius condition is more essential than the well-known maximum angle condition. It is considered that the better finite element solution can be obtained by using the mesh division consists of "good" triangles. However, the generation of such mesh division is time consuming task within the simulation process of the finite element method. On the other hand, the effecient algorithm is known for computing Delaunay triangulation. However, the mesh division produced by Delaunay triangulation sometimes contains collapsed triangles. In this paper, we will introduce "circumradius condition" and show that the effecient error estimate can be obtained by the circumradius condition with Delaunay triangulation. [ABSTRACT FROM AUTHOR]

Two phase titanium alloy-TC11 alloy and Superalloy-IN718 alloy are being considered for high-temperature structural applications in aero-engine because of their excellent mechanical properties at elevated temperatures. The mechanical properties of their forgings are sensitive to the microstructure. Therefore, it is crucial to obtain a corresponding microstructure by controlling the hot working process. For the forging of TC11 alloy, the ingot break down in the subtransus region is an important process which acted as the primary role in the transformation of lamellar structure to equiaxed one as well as its poor formability because of lower deformation temperature. In this paper, the lamellar globularization kinetics and fracture behavior during forging are studied and modeled. For the hot forging of IN718 alloy. the grain size evolution is an important process. As the δ phase in the alloy can control grain growth through the strong pinning effect, the effect of δ phase on the microstructure evolution during hot working has been considered in this paper, and the microstructure evolution model has been established. As a applications, The lamellar globularization and fracture during the subtransus cogging process of large size TC11 alloy billet, and the microstructure development during the hot forging process of IN718 alloy turbine disk have been investigated commercial FE Software with user subroutines. The prediction results showed good agreement with the actual ones. [ABSTRACT FROM AUTHOR]

Wrinkling is one of the major defects in forming processes of auto-body panels. This paper focuses on application of universal formability technology to analyze and eliminate wrinkling defect. To analyze refinedly and eliminate efficiently, universal formability technology is introduced into finite element environment. This paper presents a procedure of formability simulation analysis for wrinkles appeared on an auto fender model. The analysis results provide the approaches to eliminating wrinkles, which demonstrates the effectiveness of universal formability technology to analyze wrinkling phenomenon. The study also shows the feasibility of universal formability technology introduced into finite element environment. [ABSTRACT FROM AUTHOR]

Nonlinear contact analysis including forming simulation via finite element methods has a crucial and practical application in many engineering fields. However, because of high nonlinearity, nonlinear contact analysis still remains as an extremely challenging obstacle for many industrial applications. The implicit finite element scheme is generally more accurate than the explicit finite element scheme, but it has a known challenge of convergence because of complex geometries, large relative motion and rapid contact state change. It might be thought as a very painful process to diagnose the convergence issue of nonlinear contact. Most complicated contact models have a great many contact surfaces, and it is hard work to well define the contact pairs using the common contact definition methods, which either result in hundreds of contact pairs or are time-consuming. This paper presents the advanced techniques of nonlinear contact analysis and forming simulation via the implicit finite element scheme and the penalty method. The calculation of the default automatic contact stiffness is addressed. Furthermore, this paper presents the idea of selection groups to help easily and efficiently define contact pairs for complicated contact analysis, and the corresponding implementation and usage are discussed. Lastly, typical nonlinear contact models and forming models with nonlinear material models are shown in the paper to demonstrate the key presented method and technologies. [ABSTRACT FROM AUTHOR]

This paper shows how advanced numerical methods can help to improve the thermal efficiency of multi-holed brick walls. In order to get this objective, we will present a new methodology based on different numerical simulations. With the help of the finite element analysis (FEA), we present an optimization procedure in order to determine the best big-holed candidate brick from the thermal point of view. With respect to the ecological design and the energy saving for housing and industrial structures, there is also a great interest in light building materials with good physical and thermal behaviors, which fulfils all thermal requirements of the new CTE Spanish rule for further energy savings. On the one hand, we want to validate the numerical analysis procedure, based on the simulation of three-dimensional walls by the finite element method (FEM). On the other hand, we have analyzed the material conductivity for different compositions of the light concrete. The FEM is used for finding accurate solutions of the heat transfer equation for light concrete bigholed brick walls. Mathematically, the non-linearity is due to the radiation boundary condition inside the inner recesses of the bricks. Afterwards, the thermal optimization of the walls is carried out from the FEA of several hollow brick geometries through the average mass overall thermal efficiency and the equivalent thermal conductivity. In order to select the appropriate wall satisfying the CTE requirements, detailed instructions are given. Finally, conclusions of this paper are exposed. [ABSTRACT FROM AUTHOR]

This paper presents the research work conducted to investigate the dynamics characteristics of the offshore riser pipeline due to vortex flow and to develop a model that could predict its vortex induced responses. Glass-fiber reinforced plastic (GRP) pipe is used for this study which has smaller density from the steel. A two-dimensional finite element computational method is implemented to describe the dynamic behavior of the riser. The governing equation of motion was based on Hamilton's principle, consists of the strain energy due to bending and axial deformation, kinetic energy due to both riser and internal fluid movement and also external force from currents and waves. A direct integration method namely Newmark integration scheme is proposed to solve the equation of motion. A MATLAB program code was developed to obtain the simulation results. The natural frequency and damping ratio are presented for each mode. Dynamic response of riser is shown in time-domain and the numerical results are discussed. Several parameter effects are used to investigate dynamic responses and the results show an agreement with the theory. Vortex shedding phenomenon also has been discussed in this paper. As a conclusion, the simulation results have successfully shown the vortex induced vibration responses for GRP pipeline. [ABSTRACT FROM AUTHOR]

One main influence on the dimensional accuracy in robot based incremental sheet metal forming results from the compliance of the involved robot structures. Compared to conventional machine tools the low stiffness of the robot's kinematic results in a significant deviation of the planned tool path and therefore in a shape of insufficient quality. To predict and compensate these deviations offline, a model based approach, consisting of a finite element approach, to simulate the sheet forming, and a multi body system, modeling the compliant robot structure, has been developed. This paper describes the implementation and experimental verification of the multi body system model and its included compensation method. [ABSTRACT FROM AUTHOR]

In cold extrusion of steel tools make direct contact with the metal to be extruded. Those tools are exposed to high contact stresses which, in certain cases, may be limiting factors in applying this technology. The present paper was bound to the influence of punch head design on radial stress at the container wall in the process of cold backward extrusion. Five different punch head geometries were investigated. Radial stress on the container wall was measured by pin load cell technique. Special tooling for the experimental investigation was designed and made. Process has been analyzed also by FE method. 2D models of tools were obtained by UGS NX and for FE analysis Simufact Forming GP software was used. Obtained results (experimental and obtained by FE) were compared and analyzed. Optimal punch head geometry has been suggested. [ABSTRACT FROM AUTHOR]

A heartbeat is the consequence of cardiac tissue deforming in response to tension generated in cardiac fibres. This tension is a result of biochemical reactions that occur as part of cardiac electrophysiology. This coupled electro-mechanical system is usually modelled by coupling a model of tissue deformation with a tissue level model of cardiac electrophysiology such as the bidomain equations [1]. One difficulty with computing a numerical solution of this coupled system is numerical stability [3, 7]. In this paper we describe how numerical stability may be attained by embedding the model of generation of active tension within the tissue deformation model. [ABSTRACT FROM AUTHOR]

The subject of the paper is a symmetrical seven layer beam with foam cores and it is extended version of abstract presented by authors in [7]. The beam consists of the main core, two inner sheets, two outer cores and two external sheets. The cores are metal foams, while the sheets are metal. The analytical model of the beam is developed. The displacement is formulated with consideration of the zig-zag hypothesis of deformation of a flat cross-section of the beam and the governing differential equations for the considered beam are derived based on the stationary total potential energy. The studies are devoted to deflections of the beams under a three-point bending. The influence of the different types of cores and faces on the deflections of the beam is analyzed. Moreover, the numerical FEM-model of the beam is presented in two different FEM programs: ABAQUS System and SolidWorks Simulation. The results of the analysis are presented in Tables and Figures. [ABSTRACT FROM AUTHOR]

The mathematical modeling of the throughput-pressure behavior of the co-rotating twin screw extrusion process was subject of a variety of publications. Due to limited options within the area of numerical simulations, most of the modeling was based on analytical simplifications and adaptions. For that reason, commonly known models for describing the throughput behavior of co-rotating twin screws are based on the concept of the kinematical inversion principle. Within this concept, in comparison to the real kinematic behavior supposing the screws are rotating with a rotational velocity, the barrel is inducing the drag flow with an approximated translational velocity in the system. Further, the channel geometry is transferred to a rectangular shape with a constant channel height and is set in two-dimensional level for a simplified calculation. However, with regards to the geometrical diversity of the co-rotating systems with varying ratios of outer to inner diameter of the screws, the resulting channel geometry indicates different heights which have a significant influence on the inducing drag flow within the process. The model for the melt throughput-pressure behavior allows a variation of general screw and barrel geometry ratios but neglects the significance of the induced drag flow depending on the varying channel height. For that reason, a new method to measure the influence of the non-inverted drag flow by using 3D FEM simulations are presented in this paper. With the presented data, it is possible to extend the conventional model by considering the varying channel height and the correct induction of the drag flow with different screw ratios. The results indicate a systematical deviation between the analytical model and the data of this study. Overall, the consideration of the varying channel height increase the accuracy of the induced drag flow within the calculation of the throughput-pressure gradient. [ABSTRACT FROM AUTHOR]

B-Pillars are specifically designed to absorb substantial energy with a minimum amount of deformation to limit its intrusion in the passenger compartment during an event of side impact. In this paper, the B-pillar has been developed using composite materials, with the main objective is to improve crashworthiness performance at a lesser weight, as a replacement for steel. The three-point bending test simulations of the composite B-pillar model were modelled, which applied various parameters of materials, number of ply and additional reinforcement. The composite B-pillar design parameter that scored the highest performance to weight ratio in the numerical simulation was then fabricated using vacuum bagging method. Subsequently, the B-pillar was tested under three-point bending experimental work. The force and central displacement results were compared to simulation data and a good agreement was obtained, where B-pillar made of carbon fibre reinforced polymer (CFRP) performed better than glass fibre reinforced polymer (GFRP). The simulation and experimental results indicated errors ranging between 6 and 15%. With the additional reinforcement at the critical area, the energy absorption of CFRP B-pillar was considerably improved by 18%. The weight of the fabricated composite B-pillar was 58% lighter compared to the original steel B-pillar. These results confirmed that the novel composite material holds a high strength, and has lightweight potential to substitute steel as car B-pillar material. [ABSTRACT FROM AUTHOR]

Computer simulation tool SHeM-comp 1D for modeling one-dimensional coupled heat, moisture and salt transport is presented in the paper. The C++ code was developed at the Faculty of Civil Engineering, Czech Technical University in Prague with the finite element method implemented. The mathematical model is based on Bear and Bachmat model extended by crystallization mechanism and heat transfer. As an example of application, a historical sandstone wall subjected to climatic conditions of Prague, Czech Republic is analyzed. [ABSTRACT FROM AUTHOR]

Using the HyperXtrude module based on the Arbitrary Lagrangian-Eulerian (ALE) finite element method, the paper simulates the steady extrusion process of the asymmetric structure aluminum die successfully. A verification experiment is carried out to verify the simulation results. Having obtained and analyzed the stress-strain field, temperature field and extruded velocity of the metal, it confirms that the simulation prediction results and the experimental schemes are consistent. The scheme of the die correction and optimization are discussed at last. By adjusting the bearing length and core thickness, adopting the structure of feeder plate protection, short shunt bridge in the upper die and three-level bonding container in the lower die to control the metal flowing, the qualified aluminum profile can be obtained. [ABSTRACT FROM AUTHOR]

In this paper, comparative study on a Mannesmann roll piercing process with respect to supporting equipment including Diescher's guiding disk and Stiefel's guiding plate of shoe is carried out. The same process conditions and geometries except the supporting equipment with those of the roll piercing process found from the literature are used for the two cases. A rigid-thermoviscoplastic finite element method with intelligent remeshing capability of tetrahedral elements is employed to simulate a roll piercing process. The important of remeshing and mesh density control in simulating the roll piercing process is emphasized to minimize the numerical errors due to change of material geometry as well as smoothing of state variables. Predictions of the processes with different supporting equipment show distinct difference in plastic deformation. It has been shown that the Diescher's type is the better of the two in terms of ellipticity but that the Stiefel's type is to the contrary for spatial efficiency. [ABSTRACT FROM AUTHOR]

The current paper intends to realise a fast method for determining the material characteristics in the case of composite materials used in the airbags manufacturing. For determining the material data needed for other complex numerical simulations at macroscopic level there was used the inverse analysis method. In fact, there were carried out tensile tests for the composite material extracted along two directions - the direction of the weft and the direction of the warp and afterwards there were realised numerical simulations (using the Ls-Dyna software). A second stage consisted in the numerical simulation through the finite element method and the experimental testing for the Bias test. The material characteristics of the composite fabric material were then obtained by applying a multicriterial analysis using the Ls-Opt software, for which there was imposed a decrease of the mismatch between the force-displacement curves obtained numerically and experimentally, respectively, for both directions (weft and warp) as well as the decrease of the mismatch between the strain - extension curves for two points at the Bias test. [ABSTRACT FROM AUTHOR]

The paper presents a comparison study based on the numerical simulation with the finite element method (using the Ls-Dyna software) of incremental sheet metal forming and experimental researches regarding the same process. For this comparison study we selected four different shell formulations: Belytschko-Tsay (shell formulation number 2), fully-integrated shell formulation (shell formulation number 16) and two relatively new shell formulations Belytschko-Tsay with thickness-stretch (shell formulation number 25) and fully integrated with thickness-stretch (shell formulation number 26). In order to compare the results of the numerical simulations with the results of the experimental researches we focused on the maximum values of the main's strains, the thickness reduction and the forces on two directions. [ABSTRACT FROM AUTHOR]

This paper presents results from numerical simulations of a configuration in which a tungsten heavy alloy SRP penetrates a thick RHA 4340 steel at 2.6 km/s using the 2006 version of the Lagrangian finite element code EPIC. Penetration experimental data show improved penetration efficiency by the segmented projectiles when compared to monolithic (single solid rod) projectiles. For SRP with an aspect ratio (L/D) = 1/8, a loss in penetration efficiency was seen upon successive segment impacts. The projectile configuration considered in this study was collinear impacts of eight successive discs which measured 2mm in thickness and 16mm in diameter. The EPIC simulations considered a range of parameters that influenced the Depth of Penetration (DOP) including element-particle conversion, spacing and number of segments, failure criteria, impact velocity, and mesh resolution. The EPIC results are also compared with open-literature DOP data from simulations using an Eulerian finite element code, AUTODYN for a similar configuration. In addition, the effects of back-flowing ejecta generated by the impact of first segment on the penetration processes of subsequent segments were studied in details. An alternate SRP design is proposed in this paper to alleviate the ejecta problem. [ABSTRACT FROM AUTHOR]

The paper focuses on the miniaturization of the bulging test for material characterization of micro tubes. For the design of the experimental device, numerical simulations are conducted first. Even if no scale effect is taken into account in material modeling, numerical results give some information before designing the set-up and performing experimental works: level of pressure inside the tube, volume of fluid necessary to create such a level of pressure and bulge height to measure. The main results are a design of the experimental device and choices for its instrumentation. [ABSTRACT FROM AUTHOR]

Forming conical parts is one of the most complex and difficult fields in industries. Due to the low contact between punch and sheet in the initial stage of deformation, high stresses are applied to the sheet causing its bursting. Because most of the sheet surface in the area between the punch tip and the blank holder is free, some wrinkling will appear on the sheet wall. So, these parts are formed through multi-stage deep drawing, spinning, and explosive forming. Each of these methods has its own limitations, because of the severalty of processes in multi- stage processes, the requirement of special machines, forming safety, long forming time, etc. Few research works have been performed in the area of forming conical shapes. In this paper, forming conical parts with sharp tips has been investigated by using sheet hydroforming process. This subject has not been previously examined by any researchers. In this respect, pure copper sheet with 2 mm was formed in two forming stages. In the first stage, through the hydromechamcal deep drawing with radial pressure an uncompleted cone is formed. The optimum cone shape has been obtained through using the FEM simulation. In the second stage, through using redrawing, a cone with 8 mm tip radius has been created. By the new forming process a conical shape was produced with a good thickness distribution. [ABSTRACT FROM AUTHOR]

Solar thermal power generation systems, including direct steam generation, require isothermal energy storage systems for a saturation temperature range between 190° C and 310° C. One option to fulfill this requirement is the application of phase-change materials to absorb or release energy. In this paper, the basic concept of latent heat storage system is described, and a model of phase-change heat transfer of latent heat storage thermal unit for thermal energy storage system is built. Base on the practical thermo-physical properties of phase-change materials, Quasi-Steady State temperature distribution of phase-change heat transfer is analyzed under low Ste number. Numerical simulation (finite element method) taking account into the sensible heat is adopted and the results prove that the Quasi-Steady State temperature distribution obtained from theoretical is in good agreement with the results of numerical simulation. For a latent heat storage system with low Ste number characteristic, Quasi-Steady State solution can be used as the theoretical calculation foundation for engineering design. [ABSTRACT FROM AUTHOR]

Bimetallic components take advantage of two different metals or alloys so that their applicable performance, weight and cost can be optimized. However, since each material has its own flow properties and mechanical behaviour, heterogeneous material flows will occur during the bimetal forming process. Those controls of process parameters are relatively more complicated than forming single metals. Most previous studies in bimetal forming have focused mainly on cold forming, and less relevant information about the warm forming has been provided. Indeed, changes of temperature and heat transfer between two materials are the significant factors which can highly influence the success of the process. Therefore, this paper presents a study of the material flow in warm-forming bimetallic components using finite-element (FE) simulation in order to determine the suitable process parameters for attaining the complete die filling. A watch-case-like component made of stainless steel (AISI-316L) and aluminium alloy (AL-6063) was used as the example. The warm-forming processes were simulated with the punch speeds V of 40, 80, and 120 mm/s and the initial temperatures of the stainless steel TiSS of 625, 675, 725, 775, 825, 875, 925, 975, and 1025 °C. The results showed that the AL-6063 flowed faster than the AISI-316L and so the incomplete die filling was only found in the AISI-316L region. A higher TiSS was recommended to avoid incomplete die filling. The reduction of V is also suggested because this can save the forming energy and prevent the damage of tooling. Eventually, with the experimental verification, the results from the simulation were in agreement with those of the experiments. On the basis of the results of this study, engineers can gain a better understanding of the material flow in warm-forming bimetallic components, and be able to determine more efficiently the punch speed and initial material temperature for the process. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The paper presents numerical simulation data on the abutment pressure redistribution in rock mass during face advance, including isolines of maximum shear stress and pressure epures. The stress state of rock in the vicinity of a breakage heading is calculated by the finite element method using a 2D nonlinear model of a structurally heterogeneous medium with regard to plasticity and internal self-balancing stress. The thus calculated stress field is used as input data for 3D discrete element modeling of the process. The study shows that the abutment pressure increases as the roof span extends and that the distance between the face breast and the peak point of this pressure depends on the elastoplastic properties and internal self-balancing stress of a rock medium. [ABSTRACT FROM AUTHOR]

The present paper is aimed at working out the algorithm of multi-contact interaction of solid bodies; it studies the influence of the shape of projectile (damage agent) on its penetration capability. Steel projectiles of different shape have been considered as damage agents: sphere, regular tetrahedron, cube, cylinder and plate. The weight of projectiles has been kept the same. Antitank grenade has been used as a target. The study has been conducted by means of numerical simulation using finite element analysis. The simulation is three-dimensional. Behavior of materials has been described by elasto-plastic model taking into consideration the fracture and fragmentation of interacting bodies. The speed of interaction has been considered within the range of 800 to 2000 m/s. Research results demonstrated significant influence of the projectile shape on its penetration capability. Projectile in the shape of elongated cylinder has shown better penetration capability. Considering the weight of damage agents (except for sphere and plate) their maximum penetration capability has been reached at the speed of 1400 m/s. Increase of the speed of interaction has been followed by intensive fracture of damage agents and their penetration capability thus has worsened. [ABSTRACT FROM AUTHOR]

This paper deals with the computer modelling of tightening of the bolted connection. The analysed bolted connection consisting of the M24 metric thread is used for clamping the flexible yokes that fix the steel segments of the mine yielding support. In mining practise, it is necessary to cause the prescribed pretension in the bolted connection. One of the methods to precisely determine dependency of tightening moment on the pretension in the bolt is the finite element method. The models of the bolt and the nut were created and assembled according to drawings without shape simplification. This work was created on the basis of practical requirements from mining industry and the obtained results will be reflected in the optimization of the bolted connection. [ABSTRACT FROM AUTHOR]

The paper describes some experiences from the deterministic and probabilistic analysis of the safety of the tall building structure. There are presented the methods and requirements of Eurocode EN 1990, standard ISO 2394 and JCSS. The uncertainties of the model and resistance of the structures are considered using the simulation methods. The MONTE CARLO, LHS and RSM probabilistic methods are compared with the deterministic results. On the example of the probability analysis of the safety of the tall buildings is demonstrated the effectiveness of the probability design of structures using Finite Element Methods. [ABSTRACT FROM AUTHOR]

This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete . The results show that the ultimate capacity of the connections is improved with sectional dimension of the ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete. [ABSTRACT FROM AUTHOR]

Mechanical property improvement of rubber is widely carried out by adding carbon black or silica as a filler in rubber. In general, this improvement aims on the increase of stiffness and abrasion resistance. By means of the static straight blade indentation technique, this paper studies the mechanical properties of Unfilled Styrene Butadiene Rubber (SBR-0) and Filled Styrene Butadiene Rubber that is compounded with carbon black (SBR-25). The numerical method applied was Finite Element Analysis (FEA) in which the rubber was modeled as a hyper-elastic material and indented by a blade indenter with various wedge angles i.e. 30, 45 and 60 degrees. At the same depth of indentation, the results showed that there was an increase in both rubber stiffness and maximum stress if the rubber was compounded. However, it is found that the rubber stiffness showed a regular slight increase, while the maximum stress experienced an irregularly significant increase. Especially for the 30 degree wedge angle, the maximum stress extremely increased at a certain depth of indentation. [ABSTRACT FROM AUTHOR]

The separation systems based on dielectrophoretic field-flow-fractionation (DEP-FFF) are used for a wide range of bioparticle types, including cells, bacteria, viruses, proteins, etc. An array of interdigitated microelectrodes lining the bottom surface of a thin chamber is used to generate dielectrophoretic forces that levitate the bioparticle mixture. The balance between DEP levitation and gravitational forces determines the bioparticles position at equilibrium heights within a fluid-flow profile, and consequently determines their velocities and the corresponding elution times. The elution time depends on the voltage applied on the microelectrodes, geometry of the device, bioparticle dielectric properties and density. This paper analyses numerically the behavior of a bioparticle mixture suspended in a dense and viscous fluid under dielectrophoresis. The controlled spatial separation of bioparticle mixture is performed by a combination of dielectrophoretic and hydrodynamic forces. The theoretical background and a set of numerical results (calculated DEP force, particle trajectories, etc.) are presented. The numerical solutions are obtained using the COMSOL Multiphysics finite element solver. The presented results demonstrate that the DEP-FFF method can be successfully applicable to many biomedical cell separation problems, including microfluidic-scale diagnosis and preparative-scale purification of cell subpopulations. [ABSTRACT FROM AUTHOR]

Numerical simulation of deformation in structural elements under quasi-static thermal power and thermal radiation effects is the most important stage in the strength design and justification of nuclear power plants. Methods and software based on FEM for solving such problems should be reliably verified. Thermal creep is one of the deformation processes in the materials of structures subjected to thermal radiation. In the present paper, the numerical simulation of pipe deformation under thermal-force loading and neutron irradiation is performed. It is shown that the results of calculations using the original methods and software of finite element modeling of deformation in structures under thermal radiation loads are in good agreement with the analytical solution. [ABSTRACT FROM AUTHOR]

The subject of inquiry is a tractor unit consisting of a wheeled tractor and a hydraulic manipulator. The hydraulic manipulator is installed onto the back console of the tractor with the help of a bracket provided with a mounting plate. The question at issue is low fatigue strength of the mounting plate, which disintegrates approximately after four months of manipulator operation. The purpose of the study is Prevent fatigue disintegration of mounting plate to allow for a sufficiently long period of operation. From finite element analysis, it has been established that excessive stresses occur in the mounting plate during movement on bumpy forest drives. A new design of the manipulator’s mounting pad is substantiated, including an additional device intended to limit vertical movements of the manipulator’s beam. As a result, maximum stress at the mounting pad was reduced in half. Justifications are also given for additional possibility to increase fatigue strength of the manipulator mounting pad by means of minimizing loads onto welded joints. [ABSTRACT FROM AUTHOR]

In this paper, the heat transfer process of an injection mold heated by electricity was studied. A model used to study the transient heat transfer process was established. By using birth and death finite element simulation technique, the variation of mold temperature during the whole injection molding cycle was obtained. Engineering experiment proved that the simulated results were basically the same with the actual test results. The present method and obtained results could provide an important theoretical basis for optimizing heating rods in the mold cavity plate in order to improve product quality. [ABSTRACT FROM AUTHOR]

Micro-forming refers to the application of conventional forming processes to manufacture products from ultra-thin sheet materials. While attempting to meet the increasing demand for cost-effective manufacturing of micro-formed components, it is very important to reduce the defects in the products. In this paper, we report a number of Finite Element (FE) simulations of the micro-deep drawing process with various sample thicknesses and eccentric distances. The simulations indicated that when the sample thickness is nearly equal to the gap between the plunger and the die, the sample is likely to develop fractures at the bottom corner. When the sample thickness is much smaller than the gap, wrinkling appears in the sample. If the sheet thickness is reduced, the wrinkles approach the bending zone. If the punch-die eccentricity is increased, the pressing process results in a defective product. The simulation results compared well with experimental results. This suggests that the computer simulations can be used to design future experiments. [ABSTRACT FROM AUTHOR]

The paper deals with simulation of ejection of thermoplastic moldings from an injection mold using a consecutive combination of finite element mold filling and mechanical analyses. A new software system was developed able to predict the ejection forces, deformed shape, stresses and strains during the ejection phase of the injection molding process. A simple case study demonstrates that ejection parameters and even feasibility of the ejection itself are strongly dependent upon geometrical parameters of the moldings and design of the mold and that simple formulas are not adequate for ejection analysis. [ABSTRACT FROM AUTHOR]

This paper aims at demonstrating the interest of the Dual Mesh method in the case of incremental forming simulation. This technique offers the quality of results obtained with very fine mesh at a cost corresponding to a coarser one. The first section describes the method. In a second one, we demonstrate the method effectiveness by comparing Dual Mesh and traditional FEM both in terms of obtained results and requested computational time on two relatively simple examples. A large speed-up is obtained without compromising on quality result. In a third section, we apply the method to two more complex cases which would have been difficult to simulate without such a technique. [ABSTRACT FROM AUTHOR]

Drop test simulation via finite element methods can help simulate the effects of high impact and shock. It has become an indispensable tool during the virtual product design processes to reduce the cost of experimental test and to help improve the durability of products. The choice of a reliable contact method is critical for drop test simulation. Of all the contact algorithms, the penalty method has the advantage of taking the contact constraint into account without increasing the degrees of freedom while being easy to implement into existing software. The implicit analysis is generally known to be more accurate than the explicit analysis, but has convergence issues. This paper presents a penalty finite element method based on dynamic implicit scheme to implement impact planes for drop test simulation. An idea of impact element groups, which allows multiple impact planes with different normal directions, is presented. Two impact plane types are implemented: 'Full general' and 'Slide/no bounce'. The general drop process is divided into three durations with different time step sizes to efficiently and accurately capture the fast change within the microtime of the impact. Typical and interesting drop test models are simulated and discussed for the presented method. [ABSTRACT FROM AUTHOR]

In this paper, based on rolling technology of hot reversible rolling mill, a multi-filed coupled finite element (FE) model of hot reversible rolling process of large dimension cross-section GCr15 steel rod is established. Thermal, mechanical and microstructural phenomena during the rolling process are coupled in the model. By employing grain growth experiment, double and single hit hot compression experiments, the austenite grain size growth mathematical model and recrystallization behavior mathematical models are determined. And a designed subprogram is coupled in the FE model. Actual hot reversible rolling process of GCr15 steel is simulated using the model and the distribution and evolution of different filed-variables, such as temperature, effective strain and austenite grain size are obtained. To verify the model predictions, hot rolling experiments are carried out and the temperature and microstructure of the rolling metal are compared with the predicted results. The comparison between the two sets of data shows a good agreement. [ABSTRACT FROM AUTHOR]

A novel flexible roll forming method is proposed for manufacturing of large curved metal plates. By adjusting the position of three rows of staggered arranged rollers, a large curved metal plate is formed in an incremental way. In this paper, FE (finite element) model is established to analyze the stress-strain distribution of the deformed plates in the forming process. Based on the numerical simulation, the influence of the relative position between upper rollers and lower rollers on the dimensional accuracy of the large curved metal plate is studied. Comparison results show that roller arrangement has great influence on the dimensional accuracy of deformed plates, and process with staggered arranged rollers has the best dimensional accuracy. [ABSTRACT FROM AUTHOR]

MITICA is the ITER neutral beam test facility to be built in Padova for the generation of a 40A D- ion beam with a 16×5×16 array of 1280 beamlets accelerated to 1MV. The background gas pressure distribution and the particle flows inside MITICA accelerator are critical aspects for stripping losses, generation of secondary particles and beam non-uniformities. To keep the stripping losses in the extraction and acceleration stages reasonably low, the source pressure should be 0.3 Pa or less. The gas flow in MITICA accelerator is being studied using a 3D Finite Element code, named Avocado. The gas-wall interaction model is based on the cosine law, and the whole vacuum system geometry is represented by a view factor matrix based on surface discretization and gas property definitions. Pressure distribution and mutual fluxes are then solved linearly. In this paper the result of a numerical simulation is presented, showing the steady-state pressure distribution inside the accelerator when gas enters the system at room temperature. The accelerator model is limited to a horizontal slice 400 mm high (14 of the accelerator height). The pressure profile at solid walls and through the beamlet axis is obtained, allowing the evaluation and the discussion of the background gas distribution and nonuniformity. The particle flux at the inlet and outlet boundaries (namely the grounded grid apertures and the lateral conductances respectively) will be discussed. [ABSTRACT FROM AUTHOR]