Analytical approaches to predict flexural behaviour of curved composite beams

This thesis is concerned with the analysis of curved laminates and sandwich beams with a focus on delamination and instability.An elasticity-theory-based approach is developed for delamination and flexural strength of curved layered composite laminates and sandwich beams. The governing equations in this case are derived from the results of curved orthotropic beam on an elastic foundation under flexural loading. The approach ensures an accurate description of the through-thickness and in-plane stresses in curved laminate beams. The solutions for various geometrical configurations are provided. The effects of key parameters, such as stacking sequence of the laminate, thickness of the skin, the curvature radius etc. are studied.The critical load for instability of a curved beam on an elastic foundation, which is correspondent to the skin of sandwich beam under pure bending, is derived by beam theory and virtual displacement principle. The flexural strength of curved sandwich beam is studied with a view to identify delamination and local instability characteristics.The delamination buckling in curved composite beams is also investigated in this document. Based on linear and non-linear curved beam theory coupled with fracture mechanics concepts, two theoretical approaches are developed respectively for linear and nonlinear problems of delamination buckling which are concerned in the cases of normal delamination buckling and snap buckling of the inner layer.