Cylindrical explosion containment vessels with locally filled solid mitigants: Dynamic response and blast mitigation mechanisms

Cylindrical explosion containment vessels (CECVs) are critical for blast confinement, yet traditional global reinforcement strategies are limited by excessive weight and cost. This study proposes a novel local filling strategy, embedding solid cushioning materials with varying strengths, including polyurethane foam, aluminum foam, and aluminum alloy, into CECVs. A combined experimental and numerical simulation approach is used to comparatively investigate their dynamic response and blast mitigation mechanisms under a controlled local filling configuration. The results show that, within the tested configurations, locally filled solids significantly reduce the structural response, with the peak deformation of the steel shell decreasing by 27.6% to 53.0%. Among the tested materials, 6061 aluminum alloy produced the largest absolute deformation reduction, whereas low-density aluminum foam showed the highest mass-specific protection efficiency. Furthermore, a dimensionless material strength-impact ratio (Ψ) is introduced as a phenomenological indicator to describe the transition between energy-absorption-dominated and energy-dispersion-dominated blast mitigation mechanisms. The analysis reveals that when the effective material strength is much lower than the incident shock pressure, the medium behaves like a quasi-fluid, and the blast mitigation mechanism is mainly associated with diffraction-induced load redistribution, accompanied by momentum extraction. As the strength becomes comparable to the shock loading, the dominant mechanism shifts to energy absorption driven by significant plastic deformation or material collapse. Conversely, when the strength far exceeds the loading, the mechanism is dominated by energy dispersion, as the material's retained geometric integrity enables continuous diffraction shielding. The local filling strategy proposed in this study significantly enhances the protective performance of CECVs while effectively reducing material usage and structural weight.