Development of Nonlinear Simulation Models for a Polyurethane-based Shock Waveform Generator

This paper reports on the development of nonlinear simulation models to reproduce the dynamic response of a polyurethane-based shock waveform generator (PWG) used to generate half-sine pulses in impact tests. Two approaches were adopted. The first is a finite element analysis (FEA) model incorporating visco-hyperelastic behavior. A third-order Yeoh model was used to capture the hyperelastic characteristics identified from static compression tests, and the viscoelastic response was represented by a Prony series calibrated from stress-relaxation tests. The FEA results showed close agreement with experimental data, particularly for pulse duration. The second is a nonlinear rigid-body analysis model based on a modified Cross–Huntley formulation. Its coefficients were identified from drop-impact test data. This model reproduced the trend of nonlinear dynamic behavior associated with Shore A hardness levels and accurately predicted the peak acceleration. However, it overestimated the half-sine pulse duration. Although some discrepancies remain for each model, both approaches provide practical tools for early-stage PWG design and enable reliable evaluations of shock waveform characteristics.