Safety assessment of composite beam under ballistic impact

A novel stochastic design approach is presented for a lightweight composite to sustain ballistic projectile impact. Manufacturing of such lightweight composites is a challenging task. Presently, a significant difference is observed in probabilities of failure amongst the four different arrangements of ply lay ups in composite design. The material properties and initial projectile velocity are considered as random parameters. 3D stochastic finite element method is employed to obtain the stochastic dynamic response using explicit time domain solver. The stochastic stresses obtained at critical locations and strength parameters of random nature; contribute to damage initiation. Fiber failure initiation models adopted to establish the performance functions. The probability of failure (Pf) of anti-symmetric cross ply arrangement is found to be minimum in comparison to other ply lay-ups namely, symmetric cross ply, symmetric angle ply and anti-symmetric angle ply. Sensitivity based design optimization is carried out for symmetric cross ply arrangement based on Pf, significantly influenced by the random parameters. This information may be used effectively for design optimization to achieve better strength and lighter weight of composite beam.