Skin Wrinkling of Impact Damaged Sandwich Composite

Abstract

The effect of impact damage on the edgewise compressive properties and failure mechanism of a sandwich polymer composite is investigated. The composite was made from a thick core of polyvinyl chloride foam sandwiched between thin face skins of glass fibre reinforced polymer laminate. This material was impacted at a low energy that caused damage to the skin and at a high energy that severely damaged the skin and core. The unimpacted sandwich composite failed in edgewise compression by crimping of the foam core. When damage created by the low and high energy impacts exceeded a critical size the failure mechanism changed suddenly to wrinkling of the impacted skin. Failure by skin wrinkling resulted in large reductions to the edgewise compressive stiffness and strength of the sandwich composite. A model is proposed to determine the edgewise compressive stress required to induce skin wrinkling in impact damaged sandwich composites. Good agreement was found between the theoretical and measured skin wrinkling stresses in some cases.