颗粒增强金属基复合材料的屈服行为

运用空间轴对称弹塑性有限元方法和混合律模型，给出了应力应变分配系数与复合材料的弹性模量，屈服强度以及切线模量之间的定量关系式，并由此提出了一种新的定义颗粒增强金属基复合材料比例极限和屈服行为的方法，进而研究了颗粒形状（球体，正圆柱体以及椭球体）和材料结构参数（颗粒体积分数和颗粒根间距）对颗粒增强金属基复合材料拉伸变形行为的影响。研究表明，通过研究应力应变分析系数及其二阶导数来确定复合材料屈服行为的方法不仅适用于短纤维增强金属基复合材料，而且也适用于颗粒增强金属基复合材料。该方法可以较好地反映出颗粒形状和材料结构参数对复合材料屈服行为的影响，预测的比例极限与已发表的实验结果吻合较好。

YIELDING BEHAVIOR OF PARTICLE REINFORCED METAL MATRIX COMPOSITE

Based on the large strain axisymmetric elasto-plastic finite element and the law of mixture, the analytical expressions between the elastic modulus, the yielding stress and the tangent modulus of composite and the stress strain partition parameter were derived. A new method for defining the yield behavior of particle reinforced metal matrix composite (PRMMC) was proposed. The effects of the particles shape (sphere, unit cylinder, ellipse) and the material structure parameters (particle volume fraction, particle end spacing) on the deformation behavior of PRMMC were investigated. It was demonstrated that the method to describe the yielding behavior of composite by examining the variation of the second derivative of the stress-strain partition parameter can be used for both PRMMC and short fiber reinforced metal matrix composite. The effects of particles shape and the material structure parameters on initial yielding behavior are shown more appropriately by this new method. The predicted proportion limit is in good agreement with the experiment.