Dynamic compaction of polyurethane foam: experiments and modelling

The framework of this paper is to investigate the mitigation ability of an expanded rigid polyurethane foam against extremely fast (>10(6) s(-1)) and intense ( >10 GPa) dynamic loadings. Cyclic quasi-static tests and dynamic experiments (gas gun and low inductance generator) have been performed to investigate the foam behaviour for strain rates ranging from 10(-3) to 10(5) s(-1). Analysis of the experimental results shows that the foam has an elastic behaviour phase followed by a compaction phase with significant permanent sets. Compaction threshold is about 8 MPa under quasi-static loading, and 21 MPa for strain rates above 10(4) s(-1). A porous compaction model is used to represent the macroscopic behaviour of the foam for the whole range of strain rates. The parameters are identified from dynamic experimental results. The model is validated by comparing calculated velocity profiles with an explicit hydrocode and velocity profiles measured during the experiments.