Prediction of compressive strength of stiffened composite plate after impact

Abstract

It is important to develop numerical methods for the prediction of the residual strength of damaged structures in damage tolerance design. The buckling and postbuckling strength of stiffened composite plates with impact damage are studied numerically and experimentally. The delamination distributions through the thickness due to low velocity impact are predicted by finite element analysis. The delamination failure criterion under impact loading is modified for stiffened composite plates. The predicted delamination distributions are compared with experimental ones those are detected by an improved ultrasonic technique. To predict residual strength, a progressive failure model with degradation of elastic moduli in damaged region is adopted in a nonlinear finite element method. The degradation ratio in each sublaminate is determined by delamination distributions through the thickness of laminates. The predicted buckling and postbuckling residual strength show good agreements with experimental results. The impact damage and the postbuckling residual strength of blade stiffened composite plate are discussed.