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提出一种三维黏聚力界面损伤模型,可以描述单调和交变载荷下层合复合材料混合型的分层损伤。损伤用界面所经历过的最大位移间断来定义,交变荷载下一个周期的加、卸载过程均考虑有损伤积累,模型还考虑了单调和疲劳损伤的门槛效应和交变载荷下裂纹的闭合效应。建立了包含该界面损伤模型的初始无厚度八节点等参界面单元,并引入加速损伤的算法,用一次计算循环代替若干次实际循环,提高计算效率。用该单元模型对某复合材料动部件疲劳分层裂纹的形成和扩展进行了模拟,得到了分层裂纹前沿界面局部损伤和结构疲劳分层的发展规律,模型预测的裂纹长度荷载循环次数对数(alogN)曲线和结构剩余刚度与试验数据吻合。
A three-dimensional cohesion interface damage model is proposed to describe the delamination damage of composite laminates under monotonic and alternating loads. The damage is defined by the maximum displacement discontinuity experienced by the interface. The damage accumulation is taken into account during the loading and unloading process under alternating load. The model also considers the threshold effect of monotonic and fatigue damage and the closure effect of cracks under alternating load . The initial non-thickness eight-node isoparametric interface unit including the damage model of the interface is established, and the algorithm of accelerating damage is introduced. One calculation cycle replaces several actual cycles to improve the computational efficiency. The unit model was used to simulate the formation and propagation of fatigue layered cracks in a composite material moving part. The development rules of the local damage and structural fatigue stratification of the layered crack front interface were obtained. The logarithm of the predicted crack length load cycles (alogN) curve and structure of the remaining stiffness and experimental data.