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.