Finite element simulation of PMMA aircraft windshield against bird strike by using a rate and temperature dependent nonlinear viscoelastic constitutive model

In this study, a nonlinear viscoelastic constitutive model including the rate and temperature effect is developed to describe the mechanical behavior of polymethylmethacrylate (PMMA) material under high speed impact loading. Based on the updated Lagrangian approach, the incremented form of the constitutive model is deduced using the updated Kirchhoff stress tensors and strain tensors. Then this model is implemented with a user subroutine into the explicit dynamic finite element program LS-DYNA to simulate the dynamic behaviors of PMMA aircraft windshield under high speed bird strike. Numerical results are validated against experimental data and further investigations are carried out to study the influence of environmental temperature, impact location on windshield and bird impact velocity.