Papers by Keyword: Finite Element Analysis (FEA)

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Authors: Bang Hung Tsao, Jacob Lawson, James D. Scofield, Clinton Laing, Jeffery Brown
Abstract: Three dimensional models of both single-chip and multiple-chip power sub-modules were generated using ANSYS in order to simulate the effects of various substrate materials, heat fluxes, heat transfer coefficients, and device placement configurations on temperature and thermal stress contours. Alumina, aluminum-nitride, and CVD diamond were compared as substrates. Heat fluxes of 100 to 500 watts/cm2 resulted in SiC device junction temperatures in the range of 350 to 650 K. The predicted maximum operating temperature for a chip, to which 300 watts/cm2 of heat flux was applied, would be 239°C (512 K). In the applied heat flux range, the minimum and maximum Von Mises stress of a simulated single SiC device sub-module was between 1.2 MPa to 2.4 GPa. The maximum shear stress at 300 watts/cm2 was predicted to be 243 MPa. Both the maximum and minimum chip temperature decreased with increasing heat transfer coefficient from 25 to 2500 watts/m2 K. With modest cooling, represented by a heat transfer coefficient (hconv) of 250 watts/m2 K, SiC chips operated at 300 watts/cm2 power density maintained junction temperatures Tj < 400 K. If consistent with simulation results, CVD diamond integrated substrates should be superior to those comprised of AlN or Al2O3. Asymmetric device placement in the multi-chip module proved more effective at avoiding potential hot spots than the symmetric configuration.
Authors: Bin Li, Pedro M. Amaral, Luís G. Reis, Carlos A. Anjinho, Luís Guerra Rosa, M. Freitas
Abstract: The objective of this work is to develop analysis methods based on 3D-FEM simulations for optimum design of the diamond cutting tools under various loading conditions, considering the sintering process of diamond–metal matrix to originate residual stresses. The work concerns the use of finite element simulation for modelling of thermal residual stresses generated during the sintering process of metal matrix diamond tools normally employed by the industry. Stress distribution fields were determined for the diamond shape using a 4-node, reduced integration ABAQUS solid element type C3D4. The residual stress fields in the nearby region of a diamond particle are examined to study the effects of the sintering temperatures, the stress–strain behaviour of the metal matrix and the compression pressure on the upper surface of the metal matrix. Through the simulations of the cutting forces on the diamond, it is demonstrated that the diamond retention capacity induced by the metal matrix (important for extending the life of a diamond tool) is principally dependent on the sintering process. Optimum design of the diamond cutting tools can be achieved by selecting the appropriate sintering temperatures, the stress–strain behaviour of the metal matrix and the compression pressure on the upper surface of the metal matrix during the sintering process.
Authors: Jae Hyun Kim, Jung Yup Kim, Bong Kyun Jang, Kyung Shik Kim, Byung Ik Choi, Sang Hyun Jun, Jun Ho Kim
Abstract: In this study, we propose a simplification scheme for modeling a complex bellows structure. Using 3-dimensional finite element analysis, vibration modes and natural frequencies are analyzed. The analysis results are compared with those measured by telemetry system of acceleration. It is found that bending mode of vibration can be activated even a low operation frequency and this leads to uneven distribution of stress. The uneven distribution of stress can be a possible cause for the early failure of a bellows with a large diameter.
Authors: Jae Soon Jang, Myoung Rae Cho, Won Ho Yang
Abstract: Cold expansion method and interference fit of fastener hole have been used for over 40 years by the aircraft industry to improve the fatigue life of structures because they induce compressive residual stresses around holes. Especially, interference fits are very widely applied in the industry, because of their simple manufacturing process. There have been only few studies on the difference in the effect between cold expansion method and interference fit. The purpose of this study is to compare the effect between cold expansion method and interference fit according to plate thickness. Furthermore, residual stress distribution according to real clamping force is also investigated.
Authors: Qiu Xiang Bu
Abstract: Giant tire is characterized by low-speed high load, and conditions of use harsh. Drum is a core component of giant tire drum testing machine. Carried on the analysis to the drum's lasting quality experiment operating mode, using SolidWorks Simulation to carry on the finite element analysis (model building, grid division, boundary condition load and so on), obtained the drum's stress distributed and displacement distribution graphic solution. The quality minimum optimization design of the drum's FEA reduces the drum's design cost reasonably and shortens the design cycle effectively, has certain value engineering.
Authors: Constantin Bratianu, Paul Rinderu, Lucian Gruionu
Abstract: A 3D finite element model of a human knee was constructed to study the response of articular tissues to loads applied to the surface of the femur similar to normal and extreme movements of the joint as in sports activities. A solid model of the femoral and tibial cartilages and menisci were built from post mortem MR images of human knee at full extension using the Pro/Engineer software package. The knee kinematics data was registered for this model and successive articular surface positions were obtained as a function of flexion angle. The cartilage and menisci were modeled as nonlinear orthotropic materials and contact elements were used to compose the contact layer between articular surfaces. The model determined average contact areas and stress values, which were then compared with published experimental results for equivalent boundary conditions. The presence of menisci increased the contact area in the knee joint, thus creating lower contact stresses on the cartilage than those measured experimentally. Validation of results allows the utilization of 3D knee model for determining the contact areas and the contact stress field for diverse bones positions simulating sports activities.
Authors: Ting Wu, Wen He Liao, Ning Dai
Abstract: In this paper biomechanical behavior of dental implant and surrounding bone system are investigated under static occlusal loads through 3D nonlinear finite element analysis (FEA), taking into account the interaction of implant-bone and implant-abutment contact interfaces. Stress-based performances of four commercially-available dental implant systems are evaluated in detail, demonstrating that implant and bone stability is strongly affected by implant-abutment connection structure as well as by a number of geometrical parameters. The results also indicate that platform-switching configuration can significantly reduce the crestal bone stress peaks, which contributes to the bone preservation for long-term success.
Authors: Ding Xin Leng, Ling Yu Sun, Da Yong Hu, Yi Lin
Abstract: To explore the dynamic impact fracture behavior of nanoparticle-reinforced composites, a bottom-up numerical method was proposed and verified through the fracture process simulation of nano-SiO2/epoxy sample in Charpy impact test. At the nano-scale, a parametric micromechanics model having interphase was built. And the effective material properties of the nanocomposites with variant volume fractions were obtained. Based on the homogenization theory, the macro-scale model of impact sample was established. It is demonstrated that this proposed bottom-up method can predict the locations and directions of cracks at macro-scale, and the growth process of rupture can also be visualized dynamically. The impact strength obtained from this method has a good agreement with the measuring results in literature. And this simulation method can also be used as an assistant tool for comparing the crack propagation rate of nanocomposites with variant particle contents.
Authors: Shi Yan, Hao Yan Ma, Xue Lei Jiang, Bao Hui Qi, Fu Xue Liu
Abstract: Researches on health monitoring technology of concrete structures by using piezoelectric smart aggregates have achieved a great development. However, the technique is not widely used so far in practical engineering.   Because when constructing large-scale structural health monitoring (SHM) system using wire-based sensors, it requires a lot of cables to form a monitoring network, resulting in huge cost of abundant material of wires and labor for wire placement, and the relatively heavy maintenance work in case of failure of the SHM system. A kind of wireless sensor network based on the protocol for Zigbee802.15.4 and the passive piezoelectric smart health monitoring technology is developed in the paper. Through internal load monitoring tests of a concrete bridge model under impact loading, the developed wireless smart aggregate (WSA) health monitoring system is experimentally validated. The finite element method (FEM) is used to simulate the process as the same as the bridge model test, and the numerical results are consistent with those of the experiment. The experimental results show that the developed wireless system is stable and reliable, and can be applied in concrete bridge structure health monitoring under impact loading.
Authors: Simon P. Shone, Brian R. Mace, Tim P. Waters
Abstract: This paper concerns flexural and axial wave motion in a cracked beam. A combined finite element (FE) and spectral element (SE) model of a cracked beam is presented. A portion of the beam, which contains the crack, is modelled using FE analysis and combined with semi-infinite SEs. From the combined model the reflection and transmission coefficients of the crack are estimated. To determine the accuracy of this approach, a beam with a mass discontinuity is considered in the first instance. The reflection coefficients are estimated numerically and compared with experimental results. Secondly, a slot-type transverse crack is cut along the width of the beam. The experimental results are compared with both an FE model and a conventional lumpedparameter spring model. The purpose of this work is to investigate further the use of audiofrequency wave propagation as a basis for crack assessment and provide a valid model to use in the development of an assessment procedure.
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