基于微观图像及内聚力模型的复合材料裂纹扩展模拟

为研究材料微观结构及晶界强度对材料力学性能的影响,在晶界处引入内聚力单元模型,模拟晶间破坏过程。以ZrB_2-SiC复合材料为研究对象,将其扫描的微观结构图片进行矢量化处理,并导入ABAQUS有限元软件中建立模型,同时在其晶界处,设置内聚力单元模拟晶界破坏过程。通过改变Zr B2与Si C相界面强度,得到了晶界及材料不均匀对材料应力分布及裂纹扩展的影响。结果表明,由于晶界的存在,材料内部出现应力分布不均匀现象并产生应力集中。随着晶界强度的改变,裂纹起始位置及扩展方向发生改变,且裂纹沿低强度的界面进行扩展。随着ZrB_2-SiC界面强度增大,材料的强度提高,拉伸模量不变。

Simulation of crack propagation in composite materials using cohesive zone model and image-based numerical model

The cohesive zone model is used to simulate the intergranular fracture propagation to get the effects of the microstructure and the interfacial strength on the mechanical properties of the composites.The microstructure morphology of ZrB2-SiC ceramics illustrated by SEM was imported into ABAQUS finite element software,with the cohesive elements embedded along grain boundaries,to predict the intergranular fracture propagation.The effects of grain boundary and material inhomogeneity on the stress distribution and crack propagation were investigated by changing the ZrB2-SiC interfacial strength.The result shows an uneven stress distribution and stress concentration are observed due to the presence of grain boundaries.The locations of the crack initiation and propagation direction vary with the interfacial strengths and the crack propagates along the grain boundaries with low strength.The strength of polycrystals increases as ZrB2-SiC interfacial strength increases, and the elastic modulus remains substantially unchanged.