Buckling Response of Stitched Polyurethane Foam Composite Sandwich Structures.

Edgewise compression (buckling) tests were performed on unstitched and stitched sandwich specimens made of glass/epoxy face-sheets and polyurethane foam core. The buckling characteristics of the specimens with through-the-thickness stitches and the influence of strain rate on buckling were investigated. Ultimate load carrying capacity of the specimens was determined. Modes and causes of failure along with their relation to the buckling properties were identified. The effect of stitch row spacing on the instability preceding the crush failure was investigated using finite element analyses, which were found to explain the fracture and debonding phenomena accurately. The average sustained critical compression load increased with reduced stitch row spacing and the total buckling load decreased with decrease in strain rate, as revealed by the buckling experimental studies. [ABSTRACT FROM AUTHOR]