Study on the reactive material-illed structure under multiple impacts: Segmented fracture mechanism of the shell

The reactive material filled structure (RMFS) possesses a self-distributed energy release behavior, which enables an adaptive damage effect to the targets. Such energy release behavior strongly depends on the segmented fracture behavior of the RMFS shell under multiple impacts. To reveal the segmented fracture mechanism of the RMFS shell, an axial stress distribution model and a three-segmented radial and circumferential stress distribution model were developed, considering the coupled impact and internal deflagration loadings. A theoretical model combined with ballistic tests demonstrates that the segmented fracture of the RMFS shell is predominantly governed by the axial stress reversal effect, which originates from the internal deflagration loading. The radial and circumferential stress distributions of the RMFS shell exhibit a three-segmented pattern along the axis. Additionally, three circumferential failure modes of the RMFS shell are proposed based on the distribution characteristics of circumferential stress, namely, the complete crack, hidden cracks, and non-crack modes. The impact loading predominantly induces axial fractures at the head and tail regions of the RMFS shell, whereas the circumferential failure triggered by the internal deflagration loading results in the disintegration of its cylindrical segment. Discussion on the structure of the RMFS and the loading conditions reveals that a higher ratio of the internal-to-external cross-sectional area of the RMFS shell (Sin/Sout) reduces its resistance to internal deflagration loading, resulting in earlier axial fracture and circumferential separation occurrence.