Fracture Analysis of Adhesively Bonded Cracked Panels

Abstract

An analysis procedure is presented for predicting crack tip stress intensity factors, adhesive stiffener stresses and strains, and the residual strength of adhesively bonded stiffened panels containing cracks equally spaced between stiffeners. The approach considers the cracked skin as a linear elastic fracture mechanics problem but accounts for the effects of plasticity on both adhesive and stiffener. The solution is based on displacement compatibility between the cracked sheet and the stiffener, accounting for shear distortion of the adhesive. Displacements in the cracked sheet are determined using the Westergaard complex stress function approach. The analysis was correlated with test using data from a cracked panel, simulating typical aircraft fuselage construction, previously tested during the Air Force Primary Adhesive Bonded Structures Technology (PABST) Program.