Inverse identification of the high strain rate properties of PMMA

Abstract

Due to its low density and transparency, PMMA is frequently used as a glass substitute in aircraft and automotive components. Polymer windows are expected to resist impact loads and can be subjected to high strain rate loading (> 1000 s−1). While the quasi-static behavior of PMMA is well characterized, significantly fewer studies have looked into its high strain rate response. PMMA exhibits rate-dependent elastic and failure behavior, with both the modulus and the yield stress becoming sensitive to strain rate above a threshold of approximately 100 s−1. A new experimental technique for quantifying the response of glassy polymers at high strain rates using the virtual fields method is proposed. Samples were subjected to inertial impact tests and images of the sample deformation during the impact was captured using an ultra-high speed camera, recording at 2 Mfps. The full field displacement, strain, and acceleration were input to the virtual fields method to perform an inverse identification of the material parameters.