Sensitivity analysis of low-velocity impact response of laminated plates

• Material parameters influencing crack lengths differ from those affecting energy dissipated.
• Model validation by comparing deflections does not necessarily imply accurate energy dissipated.
• Parameters that affect energy dissipation also affect the contact force.

We analyze the sensitivity to values of material parameters, layer thickness and impact speed of the plate deflection, the contact force between the impactor and the plate, the maximum length of a crack, and the energy dissipated during the low velocity impact at normal incidence of a clamped rectangular laminate by a rigid hemispherical-nosed cylinder. The laminate is comprised of layers of polymethylmethacrylate (PMMA) and polycarbonate (PC) bonded by an adhesive, and its deformations are analyzed by the finite element method. The mathematical and computational models of the system have been described in our previous work, and their predictions compared with test data (Composite Structures, 116, 193-210, 2014). The thermo-elasto-viscoplastic materials of the PMMA and the PC and the viscoelastic material of the adhesive involve a large number of material parameters whose precise values are unknown. Here we consider values of eleven material parameters – five for the PMMA, five for the PC and one for the adhesive. It is found that values of Young's moduli and Poisson's ratios of the PMMA and the PC, and the shear modulus of the adhesive strongly influence the plate deflection and the crack length. Values of material parameters of the PC that noticeably affect its plastic deformations also determine the energy dissipation whose correlation with the second peak in the contact force between the impactor and the laminate is exhibited. The PMMA layer thickness is found to influence the crack length and the PC layer thickness the energy dissipated.