Static and Dynamic Delamination of Foam Core Sandwich Members

Abstract

Delaminationofsandwichcolumnsisstudiedusingsimplecohesivelayermodels,onewitha finitethicknessandthe other with zero initial thickness, designated, respectively, as user supplied material and user supplied element models. The latter model predicts accurately the test results of delamination of a facing sheet of a sandwich member and is seen to be more accurate than the former which predicts an earlier termination of crack growth. The user supplied elements model is applied to sandwich columns under compression. Both static and dynamic delamination problems are studied. The static problem involves monotonically increasing end-shortening, whereas the dynamic delaminationisstudiedunderconstantend-shorteningwithdelaminationssuddenlytriggered.Itisseenthatforendshortening values close to that causing delamination buckling in the static case, the dynamic delamination is abrupt and total. Two typical cases of sandwich columns, one relatively stout and the other somewhat slender, are studied and they offer interesting contrasts with the corresponding static behavior. Nomenclature d = depth of specimen E2 = transverse Young’s modulus of the cohesive layer Ex, Ey, Ez = longitudinal, transverse, out-of-plane Young’s moduli, respectively