Effects of porosity on shock wave propagation and mesostructural evolution in polyurethane foams

Polyurethane (PU) foam is widely used in blast protection due to its excellent mechanical properties and efficient shock wave attenuation. In this work, the low-intensity shock wave propagation and energy dissipation in PU foam are investigated by developing a CT-based multiscale framework that bridges mesoscopic representative volume elements (RVEs) and macroscopic finite element models. Our simulations show a non-monotonic porosity-shock attenuation relationship, with optimal attenuation at 20 %-40 % porosity under shock wave loading at a peak pressure of 4.72 MPa. Additionally, two distinct pore evolution modes dominated by energy dissipation and yield softening are revealed. The former, mainly observed at low porosity, involves localized collapse followed by partial shape recovery, while the latter, more common at high porosity, is marked by pore coalescence. Furthermore, the validity of the simulation parameters calibrated from RVEs is verified through shock wave simulations on finite element models of PU foam plates, offering a theoretical basis for blast protection and related engineering applications.