Abstract
In order to comparatively study effect of foam filling and connecting ribs on dynamic response of multi-cell thin-walled structure (MTS), high velocity (30–70 m/s) mass block impact tests were performed on empty MTS, polyurethane foam (PUR) filled MTS (FMTS) and 2nd order MTS (MTS-2nd) with connecting ribs between sub-cells. The dynamic enhancement mechanism of energy absorption of three kinds of thin-walled structures was discussed based on experimental and numerical results. The results indicate that the dynamic enhancement coefficient (DEC) of the mean crushing force (MCF) is 1.07–1.23 and 1.08–1.33 for empty MTS and FMTS, respectively. The dynamic enhancement of total energy absorption (EA) is 11.4–26.32% for MTS, 13.83–32.52% for FMTS and 4.3–9.68% for MTS-2nd, compared to the quasi-static compression. The multi-cellularization tends to degenerate the crushing force sensitivity of MTS to the loading rate, while the foam filling increases the sensitivity. The inertia effect is the main reason for the dynamic enhancement of crushing force of thin-walled structures. The coupling effect of FMTS is related to the dimensions of sub-cells, the impact velocity and the foam strength. The folding pattern and deformation stability of MTS can be improved by filling foams and increasing impact velocity. The multi-cellularization by using connecting ribs is still the most effective method to improve the specific energy absorption of thin-walled structures, although it causes a size effect and reduces the robustness of deformation modes.
Published Version
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