短纤维复合材料宏微观内聚力模型参数测量的实验与数值混合法

提出了一种改进的实验与数值混合法。该方法采用随机短纤维增强复合材料的紧凑拉伸实验,首先得到材料的宏观内聚力模型,进而确定该材料纤维基体界面微观内聚力模型参数。通过有限元法和基于场投影的反解法得到了宏观内聚力模型结果,对比分析这两个方法的结果,得出该反解法对误差的容忍度较低。随后采用改进的反解法,用数字图像相关法(DIC)直接获取宏观内聚力模型分离量,减少了该反解法未知数的数量,提高了容错率。再将DIC和改进的反解法结合,对该材料裂纹尖端宏观内聚力区的牵引力进行了反解。采用双线性内聚力模型,根据Mori-Tanaka方法,将求得的宏观内聚力定律与纤维基体界面微观内聚力定律关联起来,从而求得了纤维基体界面微观内聚力模型参数。该方法和结果可为短纤维增强复合材料纤维基体界面的微观力学分析提供实验基础。

Experimental-numerical hybrid method for measurement of cohesive zone model parameters of short fiber composites in both macro and micro scale

An improved experimental-numerical hybrid method was proposed. Compact tension experiment of the random short fiber reinforced composites was used in this method, and macroscopic cohesive zone model (CZM) of the material was obtained firstly, then the microscopic CZM parameters of the fiber/matrix interfaces of the material were obtained. The macroscopic CZM results were obtained by both finite element method and the inverse extraction based on field projection method. By comparing the results of the two methods, the fault tolerance of the inverse extraction method was found to be lower. Then the improved inverse extraction method was adopted, and the separation amount of macroscopic CZM was directly obtained by digital image correlation method (DIC), so that the amount of unknowns in the inverse extraction method was reduced, and the fault tolerance was also improved. The DIC and the improved inverse extraction method were combined, and the traction of macroscopic cohesive zone at the cracktip of the material was inverse extracted. The bilinear CZM was adopted, and the Mori-Tanaka method was used to link the macroscopic cohesive law obtained above and the microscopic cohesive law for fiber/matrix interfaces. The model parameters of microscale cohesive of fiber/matrix interfaces were also determined. This method and the results provide an experimental basis for the micromechanics analysis of the fiber/matrix interface of short fiber reinforced composites.