Experimental Investigation of Flange and Web Crippling of Blade Stiffened Composite Panels

Stiffened composite panels are widely used in aeronautical applications. The crippling failure of blade stiffened composite panels has not been clearly understood. Often, semi-empirical equations are used in the preliminary design of these panels. Valid tests shall be undertaken to qualify new composite materials for their use in aircrafts. In this paper, experimental investigations are presented to predict the crippling strength of carbon-epoxy blade stiffened panels. To undertake the crippling tests for flange and web sections, two experimental setups were presented. These test results are validated using linear and non-linear finite element analyses for a static compression loading. Crippling design curves similar to the composite material handbook (CMH17) were computed using non-dimensional parameters. For both the flange and web specimen test results, the design curves are slightly higher than the CMH17 data. It is concluded that the composite material handbook design curves are conservative to use.