材料断裂内聚力区牵引-分离曲线的测量方法研究

On the measurement method of traction-separation curve in material fracture cohesive zone model

内聚力模型是模拟复合材料界面分层、脱粘等力学行为的有效工具。本文分别提出了改进的直接测量法和交互M积分反解法来测量材料的内聚力区牵引-分离关系曲线。在紧凑拉伸断裂力学实验的有限元数值模型中,分别应用两种方法测取了内聚力模型的牵引-分离曲线。通过与有限元数值解和交互J积分反解法的比较,验证了方法的准确性。本文以20%和49%纤维体积含量的随机云杉短纤维增强聚丙烯复合材料（云杉/PP）为例,分别应用改进的直接测量法、交互M积分反解法和交互J积分反解法得到了该材料内聚力区的牵引-分离曲线。三种方法结果的对比验证表明：三种方法得到的牵引-分离曲线变化趋势一致,曲线所反映的材料内聚力区强度、初始损伤和完全破坏分离量大小以及断裂的能量释放率等主要内聚力参数能够吻合,它们的测取结果都能够完整地描述内聚力区材料的力学行为。

Cohesive zone model（CZM）is an effective tool to simulate delamination,debonding and other mechanical behaviors of composite material.In this paper,an improved direct method of measurement and an interaction M-integral inverse method are proposed to measure material′s traction-separation relation curve in CZM.In finite element numerical model of compact tensile fracture mechanics experiment,the traction-separation curve in cohesive zone model were measured by two methods,respectively.The accuracy of the method was verified by comparing with finite element numerical solution and results from interactive Jintegral inverse method.In this paper,random spruce short fiber reinforced polypropylene composite（spruce/PP）with 20% and 49% fiber volume content is taken as an example,the traction-separation curves in cohesive zone were obtained by using improved direct method of measurement,interactive M integral inverse method and interactive J integral inverse method,respectively.The comparison of results obtained from three methods proves that the variation trend of traction-separation curves obtained by three methods is consistent;the main cohesive parameters reflected by curves,such as cohesive strength,initial separation,debonding separation and fracture energy release rate etc.,are all consistent. Measurement results can completely describe material′s mechanical behavior in cohesive zone.