In the past viscoelastic materials have been simulated with springs and dampers. It was found that this simulation was very poor for polyurethane foam, a viscoelastic material having general use.This paper describes techniques for simulating the force-penetration properties of viscoelastic materials. It is based on results of pendulum impact tests on polyurethane foam. Sample thickness, impact velocity, and impactor shape were varied, with four replications of each test. The simulation accounts for the effects of the variables and gives a very close approximation to the test data.A dynamic-property comparison index is suggested for evaluating foam materials. This index is a ratio of absorbed energy to peak deceleration.