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The energy absorption characteristics of a stitched sandwich panel were investigated using experimental and analytical techniques. The structural stability aspects of the proposed mechanism were evaluated using the existing buckling and wrinkling theories. The effect of through-the-thickness stitches on the stability characteristics was investigated using finite element analysis. The configuration of the energy absorption mechanism was based on the stability analysis. The actual energy absorption process was characterized by conducting static crush tests. The experimental results indicated an increase in energy absorption capability with smaller stitch spacing and also resulted in smoother load deflection curves. A broad design guideline was developed for the design of a sandwich panel for energy absorption, based on stability analysis and experimental results.

The coupled influence of material configuration (number of facesheet plies, core density, core thickness) and impact parameters (impact velocity and energy, impactor diameter) on the impact damage resistance characteristics of sandwich composites comprised of carbon-epoxy woven fabric facesheets and Nomex honeycomb cores was investigated using empirically based quadratic response surfaces. The diameter of the planar damage area associated with TTU C-scan measurements and the peak residual facesheet indentation depth were used to describe the extent of internal and detectable surface damage, respectively. Estimates of the size of the planar damage region correlated reasonably well with experimentally determined values. For a fixed set of impact parameters, estimates of the planar damage size and residual facesheet indentation suggest that impact damage development is highly material and lay-up configuration dependent.