Effects of environmental temperature and interfacial friction on the micromechanical properties of fiber reinforced polymer composites

A modified cohesive zone model (CZM) incorporating environmental temperature and interfacial friction effects was proposed to simulate the fiber/matrix interface. Concurrently, a micromechanical model for composite materials accounting for thermo-frictional effects was developed through an algorithm-generated representative volume element (RVE) with randomly distributed fibers, combined with the temperature-dependent elastic modulus of the polymer matrix. To validate the micromechanical model, microdroplet debonding tests and mechanical tests on unidirectional composite laminates were conducted under both ambient and cryogenic conditions. The simulation results demonstrated excellent agreement with experimental measurements. An analysis was performed on the microscopic failure mechanisms of the composite material. The results indicated that the reduction in ambient temperature enhances the interfacial shear strength and transverse compressive strength, the presence of a thermal stress field, as well as the influence of temperature on the properties of both the matrix and the interface, collectively alter the micro-mechanical behavior under different temperature conditions. Furthermore, under compressive loading, interfacial friction plays a critical role in the failure process of the composite, thereby exerting a substantial influence. A notable variation in the extent of interfacial damage is observed locally.