Testing and multiscale modeling of a foam-based lung surrogate subjected to underwater shock loading

A combined experimental and computational study was conducted to investigate the structural response of a foam-based lung simulant subjected to underwater pressure wave. In the physical experiments, a lung surrogate made from porous medium was exposed to underwater pressure wave in an impact force - driven testing tube. The pressures in the water and surrogate deformation profile were recorded throughout the event. A numerical model of the underwater shock tube was developed using finite element (FE) method and validated against experimental data. An arbitrary Lagrangian-Eulerian (ALE) fluid–structure coupling algorithm was then utilized to simulate the interaction between the underwater pressure wave and the lung surrogate. Based on the numerical model, a multiscale modeling strategy was used to link the surrogate responses in macro and micro scales. The modeling process consists of two steps, namely (1) macro scale FE modeling to predict the overall surrogate reponse; and (2) micro scale Representative Volume Element (RVE) modeling for the detailed microstructure response. The strain tensors computed in Step (1) were applied to the RVE as the boundary condtions in Step (2) to calculate its response in the micro scale. With this multiscale modeling approach, a parametric study was carried out to study the influence of waveform on the RVE strain response. The results indicate that for current input pressure levels, the strain response within the foam surrogate model is more sensitive to the overpressure than the duration of pulse. The modeling approach developed in this work can potentially serve as a basis for further numerical models to gain a deeper insight into the mechanism of underwater blast-induced lung injury.