Energy exchange mechanism between blast wave and expansion tube.

• This article elucidates the energy exchange mechanism between blast loading and energy absorbing structures through the proposed theoretical analysis model. • Energy exchange efficiency (EEE) is positively corrected with the peak overpressure and specific impulse of reflected wave, as it enhances the reflection coefficient. • Increasing areal density of ETS enhances impulse transfer while impending energy exchange with the blast wave. • Effective impulse of reflected wave is inversely corrected with equivalent strength of ETS, leading to a reduction in EEE by increasing equivalent strength. The mechanical response and energy absorption characteristics of the energy-absorbing structure under blast loading are widely concerned in engineering protection, while the energy exchange mechanism remains poorly understood, thereby limiting improvements in energy absorption performance under blast loading. This paper utilizes the expansion tube structure (ETS) as a typical energy-absorbing structure to investigate the energy exchange mechanism under blast loading. Following an experimental verification, numerical simulations are conducted to investigate the effect of relevant parameters on the energy exchange characteristics. A theoretical model based on the strong-shock hypothesis is developed and validated against numerical results to predict the energy absorption efficiency of ETS under blast loading. The findings reveal that increasing the areal density of ETS positively impacts impulse transfer, but does not contribute significantly to energy exchange between the blast wave and ETS. Notably, there exists a significant negative correlation between the energy exchange efficiency and areal density. An approximately linear positive correlation is observed between the energy exchange efficiency and both peak overpressure and specific impulse of the reflected wave due to an enhanced reflection coefficient of the blast wave. Moreover, increasing equivalent strength leads to a decrease in energy exchange efficiency as it negatively correlates with effective impulse of the reflected wave. This study elucidates the underlying mechanisms governing energy exchange in expansion tube under blast loading, providing valuable insights for optimizing designs of energy-absorbing structures. [Display omitted] [ABSTRACT FROM AUTHOR]