Mechanical performance of water-blown polyurethane foams at varying densities under impact loading: Experimental and numerical investigation

Water-blown polyurethane foams, produced using water as a sustainable blowing agent, exhibit complex, density-dependent mechanical behavior that is pivotal for energy absorption in impact-resistant structures. Compared to traditional chemical blowing agents, the water-blowing technique offers improved environmental compatibility, avoiding harmful effects associated with conventional methods. This study comprehensively investigates the mechanical performance and perforation energy absorption of these foams under high-velocity impact loading, employing both experimental testing and advanced numerical simulation techniques. Foam specimens, with densities ranging from 60 to 200 kg/m 3 , were subjected to compression tests to accurately determine their elastic modulus, plateau stress, and densification strain. High-velocity impact tests were conducted using a gas-gun apparatus to launch spherical impactors at an initial velocity of 147 m/s, thereby providing critical insights into the foam’s dynamic energy dissipation and perforation behavior. A detailed numerical model was developed in ABAQUS utilizing a custom VUMAT subroutine for foam material that integrates an energy-based damage criterion, wherein the critical energy parameter W was meticulously calibrated against the experimental impact test data. Predictive models were established through systematic curve fitting of the experimental results, enabling reliable interpolation of key mechanical properties across the specific density range. The simulation results reveal distinctly nonlinear trends in both the residual velocity of the impactor and the specific perforation energy as foam density varies. Notably, although increasing foam density generally enhances energy absorption capabilities, the improvements become marginal within the density range of 100–150 kg/m 3 , exhibiting minimal changes in specific perforation energy. In contrast, density increments below and above this range yield more pronounced changes, highlighting critical density intervals for optimized energy absorption. This eco-friendly approach, combined with optimized mechanical performance, provides a robust framework for designing advanced, impact-resistant, and sustainable energy-absorbing systems made of polyurethane foams.