System probability of failure and sensitivity analyses of composite plates under low velocity impact

Abstract

Probabilistic response of graphite epoxy composite plates under low velocity impact is studied modeling matrix cracking and delamination damage. Probabilistic design methodology of composite material based on progressive damage model is developed and implemented in a user defined subroutine to consider the scatter in material properties (Young’s moduli, Poisson’s ratio, ultimate strength, and fracture energy) and in initial velocity. Damage initiation and propagation failure due to matrix cracking and delamination are investigated for limiting criteria for the low velocity impact. The Gaussian process response surface method, is adopted to determine the system probability of failure and sensitivity analyses of the composite plates. The scatter in random parameters shows significant influence on the contact force and displacement histories. There is a probability of underestimation of the peak contact force and displacement by 28% and 44% respectively, if the scatter in the properties is not considered. The target reliability of the plate is achieved for an optimal combination of impactor masses and velocities. The sensitivity based probabilistic design optimization procedure is investigated to achieve better strength and lighter weight of composite for body armors.