Low-velocity impact and post-impact biaxial residual strength tests and simulations of composite laminates

The failure and biaxial residual strength after low-velocity impact of composite laminates are very important in the service and maintenance of aero-engine. In this paper, cruciform structure and cruciform structure with slots were designed and used for impact WA and post-impact biaxial tensile test, respectively. Experimental results showed that damage evolutions under biaxial loading vary greatly for different impact energies. Subsequently, a full process analysis method for low-velocity impact damage and biaxial residual strength of composites was proposed and used to simulate the low-velocity impact damage and biaxial residual strength. The comparisons between the simulation results and tests showed that the maximum error of the impact projection area and biaxial residual strength is less than 10%, proving the accuracy of the simulation results and the rationality of the full process analysis method developed in this paper. M last, the biaxial strengthening effect and the effects of impact energy on the biaxial residual strength were analyzed. The simulation results showed that (1) T300/QY8911 composite laminates has the property of biaxial strengthening effect; (2) There are two thresholds of impact energies for the post-impact biaxial residual strength, which are located in the ranges from 7.5-J to 10-J and from 15-J to 17.5-J, respectively.