Degradation mechanism of CFRP mechanical properties in acid thermal environment

Carbon fiber reinforced resin matrix composites (CFRP) have been widely used in aerospace and other fields due to their advantages of high specific energy absorption, high specific strength and high specific modulus. However, CFRP is inevitably exposed to corrosive environments such as acid rain during long-term service. The lack of in-depth and systematic research on the performance evolution of CFRP under acid-heat coupling environment has become a key bottleneck restricting its reliable application in complex working conditions. In order to explore the degradation mechanism of mechanical properties of CFRP in acid-heat environment, the acid-heat aging test of CFRP was designed and the mechanical properties of materials were tested. The results showed that the acid-heat environment can cause the degradation of the matrix and the weakening of the fiber-matrix interface, which leads to the abnormal increase of the tensile strength of CFRP. The longitudinal and transverse tensile strength were increased by 93.85% and 7.14%, respectively, reflecting the load transfer mechanism dominated by carbon fiber. The longitudinal and transverse compressive strength decreased by 39.96% and 34.14%, respectively. The main reason is that acid corrosion leads to the degradation of CFRP interface bonding performance and weakens the overall bearing capacity of the material. A refined finite element model of CFRP was established using ABAQUS. The constitutive relationship of the material was defined by the VUMAT subroutine, and the cohesive contact was introduced to simulate the failure behavior of the fiber-matrix interface. The maximum error between simulation and test was within 9.28%, which verifies the validity of the model and provides theoretical basis and technical support for the long-term performance prediction and reliability design of CFRP in acid-heat environment.