Analysis of sandwich panels with multiple-site damage

Hail impaction may cause multiple-site damage to sandwich panels used as a part of control surfaces and is therefore a major maintenance and repair concern for the airlines. A strength analysis of the damaged sandwich panels is essential to predict the influence of the multi-site damage, which is necessary for establishing allowable damage limits. The location of the damage sites in relation to each other and their size influence the stress field significantly. This study presents an analytical method to determine the stress distribution in sandwich panels with arbitrarily located damage, that is elliptical or circular in shape. The validity of this method is established by comparison against the three-dimensional finite element models of sandwich panels with multiple damage zones.