Debonding Criterion in the Push-Out Process of Fiber-Reinforced Titanium Matrix Composites

摘要

In this paper, the interfacial fracture process during the push-out test was subjected to finite element analysis using a three concentric axisymmetrical model which consisted of fiber, matrix, and composites. A stress criterion and an energy criterion for debonding were used to determine the interfacial shear strength and interfacial fracture energy respectively for different test temperatures based on the measured maximum load to break the fiber/matrix bond. Load versus displacement and load versus debonding length behavior during the push-out test are modeled as a function of various factors (such as testing temperature, frictional coefficient and so on) under different interfacial strengths. The critical interfacial strength and the critical energy release rate of SCS-6/IMI 834 titanium-matrix composites in the temperature range of room temperature to 530°C were determined as a function of testing temperature. It is found that the stress criterion is dependent on the size of element. The critical interfacial strength obtained is somewhat arbitrary because of singular stress fields in front of the crack tip. The energy criterion applied is principally independent on the size of the element. So it seems that the energy criterion is a more appropriate way to characterize the interfacial bond.