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Fig. 7. (A) Normalized maximum deflection of the top face of the square honeycomb sandwich panel (dashed lines) and counterpart solid plate (solid lines) made of HY80 subjected to two shocks versus core relative density. (B) Maximum core crushing strain at the center of the square honeycomb sandwich plate versus the relative density of the core. (C) Deformed configuration of square honeycomb sandwich panels with three different core densities subjected to two consecutive shocks loading with peak over-pressures 100 and 80 MPA, respectively. In all diagrams, no failure criterion is incorporated for HY80, and sandwich panel has M = 156 kg/m2 and L = 1 m.
This and the next image are from:
Hamid Ebrahimi and Ashkan Vaziri (Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, United States), “Metallic sandwich panels subjected to multiple intense shocks”, International Journal of Solids and Structures, Vol. 50, Nos. 7-8, pp 1164-1176, April 2015, https://doi.org/10.1016/j.ijsolstr.2012.12.013
ABSTRACT: The mechanical response and fracture of metal sandwich panels subjected to multiple impulsive pressure loads (shocks) were investigated for panels with honeycomb and folded plate core constructions. The structural performance of panels with specific core configurations under multiple impulsive pressure loads is quantified by the maximum transverse deflection of the face sheets and the core crushing strain at mid-span of the panels. A limited set of simulations was carried out to find the optimum core density of a square honeycomb core sandwich panels under two shocks. The panels with a relative core density of 4%–5% are shown to have minimum face sheet deflection for the loading conditions considered here. This was consistent with the findings related to the sandwich panel response subjected to a single intense shock. Comparison of these results showed that optimized sandwich panels outperform solid plates under shock loading. An empirical method for prediction of the deflection and fracture of sandwich panels under two consecutive shocks – based on finding an effective peak over-pressure – was provided. Moreover, a limited number of simulations related to response and fracture of sandwich panels under multiple shocks with different material properties were performed to highlight the role of metal strength and ductility. In this set of simulations, square honeycomb sandwich panels made of four steels representing a relatively wide range of strength, strain hardening and ductility values were studied. For panels clamped at their edge, the observed failure mechanisms are core failure, top face failure and tearing at or close to the clamped edge. Failure diagrams for sandwich panels were constructed which reveal the fracture and failure mechanisms under various shock intensities for panels subjected to up to three consecutive shocks. The results complement previous studies on the behavior and fracture of these panels under high intensity dynamic loading and further highlights the potential of these panels for development of threat-resistant structural systems.
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