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Different material properties leads to different metal fracture behaviors.Even if the powder material is composed of plastic metal,the fracture still does not show macroscopic plastic deformation characteristics if the material contains a large number of voids.Eight-node isoparametric elastic-plastic finite element method was used to simulate the tensile process of sintered powder material.By setting a number of voids in the analyzed metal cuboid,the initial density was taken into consideration.The material properties of the three-dimensional solid for the tensile simulation were defined with reference to the known pure iron material parameters,The load-displacement curves during elongation were obtained with a universal testing machine,and then the simulated curves were compared with the experimental results.The factors that cause the stress concentration and strength decrease were analyzed according to the simulated equivalent von Mises stress distribution. 相似文献
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为了探究材料力学性能对超声冲击处理焊后应力应变的影响,采用有限元分析软件ABAQUS建立了不同力学性能参数的超声冲击模型.分别讨论了弹性模量、泊松比以及静态屈服强度对超声冲击处理后材料应力应变的影响,旨在探讨超声冲击处理对不同力学性能材料的应力应变强化程度.结果表明,材料的弹性模量、泊松比以及静态屈服强度都会影响超声冲击处理的应力应变;且冲击处x方向应力随着材料的弹性模量、泊松比以及静态屈服强度的增加而增大;而等效塑性应变会随着弹性模量和静态屈服强度的增加而变小,随着泊松比的增加而增大;泊松比对等效塑性应变影响大于x方向应力的影响. 相似文献
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S. A. Krishnan G. Sasikala A. Moitra S. K. Albert A. K. Bhaduri 《Journal of Materials Engineering and Performance》2014,23(5):1740-1749
A local damage approach based on plastic strain equivalent to uniform strain and grain diameter of the material is proposed for prediction of crack initiation. Plane strain, plane stress, and 3D FEM simulations are carried out for compact tension (CT) geometry with blunt notch of different a/W ratios under mode-I loading. Elastic-plastic fracture parameters have been estimated based on certain assumptions on blunting at notch tip and micromechanisms of events leading to onset of crack. The various crack initiation parameters evaluated based on proposed local damage approach and initial assumptions have been verified by conducting experiments on CT specimens and subsequent scanning electron microscopy study on fracture surface. The laboratory scale experimental results of AISI 316L(N) stainless steel material are in good agreement with FEM-predicted fracture parameters for notch type of stress raisers. The local damage approach and FEM procedure established in the present study would be easily extendable to the analysis of stress raisers in components for the prediction of crack initiation under elastic-plastic condition. 相似文献
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双孔模型材挤压过程的有限元分析 总被引:2,自引:0,他引:2
本文采用大变形弹塑性有限元理论 ,对双孔模型材挤压成形过程进行了有限元分析。模拟了双孔模非对称角铝型材挤压变形过程 ,获得了挤压变形时网格畸变、流速、应力和应变分布 ,展示了型材挤压件变形不均匀细节。并与单孔模型材挤压过程进行了比较 ,发现双孔模[1] 挤压时 ,变形体内存在两个互为相反方向的涡流场 ,它们相互抵消 ,从而可以消除型材挤压过程中产生的扭拧、波浪、弯曲等缺陷。为提高挤压件质量 ,优化设计多孔型材挤压模以及制定合理的工艺 ,提供了理论依据 相似文献
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X65管线钢焊接接头H2S应力腐蚀研究及其有限元数值分析 总被引:5,自引:0,他引:5
在X65管线钢H2S应力腐蚀试验的基础上,建立了三维弹塑性有限元模型.通过三维弹塑性有限元的数值分析,得到了裂纹尖端应力场分布和氢浓度的分布特征.通过对X65管线钢焊接接头的显微组织观察和基本力学性能研究,对影响其应力腐蚀影响因素提供了实验依据.并根据楔形张开加载恒位移试样得出了X65管线钢焊接接头的临界应力强度因子KISCC和裂纹扩展速率,其应力腐蚀试验结果在有限元数值分析中得到了验证。 相似文献
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Failure assessment of the integrity of a ductile flawed structural component is done currently by a one-parameter fracture
mechanics approach. The J-integral is the one-parameter used; it has proven to be useful in order to predict ductile crack initiation. However, when
tension loading dominates and/or a fully plastic condition develops around the crack, the J-integral alone does not describe completely the crack-tip stress field and a second parameter is needed. In this work, an
accurate modeling of the elastic-plastic stress field around a deep crack in a three-dimensional three-point bend specimen
is carried out. Numerical results for the crack-tip stress field are used to evaluate a crack-tip constraint parameter Q, in terms of applied loading, from contained plasticity to large-scale yielding. The parameter Q, measures the degree of stress triaxiality and constraint around the crack-tip. In order to obtain the stresses in the near-crack-tip
field with high accuracy, a detailed mesh with higher order three-dimensional finite elements is located around the crack
front. The modeling of crack-tip blunting deformation is performed by using a small notch radius in the crack-tip. Large-strain
and finite-rotation nonlinear behavior effects around the crack-tip are included. The material, an ASTM A 516 steel, is modeled
with incremental theory of plasticity. Numerical results of the Q triaxiality parameter are presented for increasing level loads to obtain an extended yield condition. Additional results
of J-integral parameter and crack-tip opening displacement, for different load ratios and for different position across the specimen
thickness are shown. 相似文献