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Complex composite parts, and especially curved laminated composites, are more subject to defects than flat laminates. One of the most common defects is the presence of wrinkles, which can occur in the radius of curvature. Wrinkle effects must be studied to evaluate their influence on the mechanical properties of laminated composites. In this study, a numerical model was developed to take wrinkle and local delamination defects into consideration and assess their impact on the failure load of L-angle specimens under four-point bending tests. Experimental wrinkles based on a previous work were modelled using the Discrete Ply Model strategy and four-point bending simulations were run. The numerical model allowed the effects of each defect (local delamination and wrinkle) to be distinguished and their combined influence on the failure load to be studied with respect to the maximum misalignment. [ABSTRACT FROM AUTHOR]

Highly curved laminated parts are used at the junction between two different perpendicular panels on aircraft primary structures. Usually, these laminates fail by delamination due to a bending moment, which appears when the part is loaded. The bending moment tries to flatten the part and out-of-plane tensile stresses are generated in the curvature. This failure is traditionally called unfolding failure. The modelling strategy called the 'Discrete Ply Model' (DPM) is used to simulate four-point bending tests on L-angle specimens. Experimental results of four point bending tests carried out at ONERA are used to validate the approach. Four different stacking sequences with the same thickness are taken into consideration in this study. In a second part, a sensitivity analysis on frictional coefficient, intralaminar matrix cracking, transverse tensile and shearing strength, and critical energy release rate in modes I and II is performed numerically and provides an original explanation of the failure scenario and the most influential parameter. [ABSTRACT FROM AUTHOR]