In situ characterization and numerical simulation of cavitation upon explosive decompression in a gas-saturated elastomer
This thesis was focused on cavitation damage in rubbers submitted to gas decompression. Previous studies have shown cavities appearance in elastomers when a level of hydrostatic loading is reached. Cavitation may also occur on rubbers saturated with a gas pressure when this pressure is suddenly removed. Purely mechanical criterions were used in order to predict cavitation damage observed under gas-loading. The first step of the study consisted in a temporal and spatial experimental characterization of the of the damage appearance conditions. A macroscopic pressure or a critical hydrostatic stress were not able to fully predict all experimental results. Gas diffusion adds a non-negligible temporal aspect. These results justify the coupled diffuso-mechanical study with a numerical model at the scale of the cavity. This model consisted in a cavity placed at the center of an incompressible hyperelastic sample submitted to both mechanical loading and gas saturation. This hollow sphere model has allowed observing a stable growth of the cavity during an entire cycle, with a swelling phase during decompression. A critical elongation criterion was used during this swelling phase to qualitatively and quantitatively reproduce experimental results concerning the effect of the gas cycle on the time of appearance of the first cavity. In addition, the numerical model was able taking into account the distance from the cavity to the free surface of the sample, which has never been modeled before.