Interface fracture assessment on honeycomb sandwich composite DCB specimens

► Modified elastic foundation model to analyse sandwich DCB specimens. ► Validation of the model by performing the complex 3D finite element analysis. ► Improved procedure is proposed for evaluating the interface fracture toughness. ► Failure load estimates of sandwich DCB specimens match well with existing test results. This paper deals with the fracture analysis on the honeycomb sandwich composite double cantilever beam (DCB) specimens. Analytical expression for the strain energy release rate (GI) of the specimen is derived from modified elastic foundation model utilising the compliance derivative method. The results obtained from 3D finite element analysis for various delamination lengths compare well with the analytical results. A simple and improved procedure is suggested for evaluation of the interface fracture toughness (GIC), which takes into account the scatter in fracture data, and demonstrates its validity through comparison of existing test results with estimated failure loads.