有限元模拟SiC增强Al基复合材料的力学行为

Simulation of mechanical behaviors of SiC reinforced Al matrix composites by finite element method

采用有限元方法和轴对称单胞模型模拟了增强体(SiC)形状、体积分数以及不同基体类型对铝基复合材料力学行为的影响。模拟结果表明:增强体的加入会阻碍基体的塑性流变,使基体内发生非均匀变形,在增强体尖角处出现应力集中;椭圆柱形增强体对基体塑性变形的阻力最大,传递载荷的能力最强,因此强化效果最好。在一定范围内,随着增强体体积分数的增加,基体与增强体之间的比表面积增大,有利于载荷的传递;增强体体积分数的增加导致颗粒间距减小,几何必须位错自由运动的路径减少,复合材料的强度也随之增加。此外,不同类型基体自身的塑性流变能力不同,Al-Zn-Mg基体强度最高,在拉伸变形过程中,受到增强体的阻碍作用最大,会有更多的载荷从基体传递到增强体,以Al-Zn-Mg为基体的复合材料的强度最高。

The effects of reinforcement shape,volume fraction and matrix type on the mechanical behaviors of Al matrix composites were studied by finite element method based on the axisymmetric unit cell model.The simulation results show that the addition of reinforcement particles can inhibit plastic flow of the ductile matrix and result in non-uniform deformation of the matrix,with the stress concentration presenting around the particle corner.The truncated cylinder-shaped SiC particles have the maximum inhibition on the plastic flow of the ductile matrix and result in higher load transferring ability of the reinforcements.When the volume fraction of reinforcements is small,the interfacial area between the SiC particles and the matrix increases with the volume fraction of the SiC particles increasing,and thus more load can be transferred from the soft matrix to the hard SiC particles.At the same time,the dislocation strengthening effect increases with the decrease of the particle interspacing.Different types of Al matrixes have different flow abilities.During the tensile deformation process,the composite with Al-Zn-Mg matrix has the highest strength due to the higher strength of Al-Zn-Mg matrix and more load transferred from the matrix to the reinforcement.