A SIFT approach for analysing failure by delamination and disbonding in composite structures

摘要

A strain invariant failure theory (SIFT) has been developed to predict resin failure in damaged and pristine composite structures The finite element (FE) analysis in this work uses shell elements consistent with common practice in the aeronautical industry. The new SIFT is similar in nature to a characteristic length method that requires a matched finite element mesh. It samples the strains in brick elements lofted between two layers of shell elements, each representing half of the damaged laminate in the failure critical zone. Experimental tests involving three laminate materials have been carried out to validate t he modified SIFT approach for notched laminates, including single and multiple level delamination tests, and stiffened panel tests under shear or compression load. These results are summarised in a table. Square and rectangle single delamination tests are presented in more detail and indicate that failure location and load predicted by the modified SIFT approach correlates well with the experimental results.