Utilizing numerical models to identify process-induced residual stresses in 3D woven carbon/epoxy composites

Abstract

A combined experimental-numerical procedure is proposed to evaluate residual stresses in 3D woven carbon/epoxy composites. It is assumed that residual stresses are caused by the difference in thermal expansion coefficients of the constituents. The impact of residual stresses is quantified by drilling blind holes in the composite panels and mapping the resulting in-plane surface displacements by digital image correlation and electronic speckle pattern interferometry. Then mesoscale finite element models of the composite are used to determine the effective temperature drop ΔTeff that results in the same predictions for hole drilling. The local distributions of residual stress are given by the finite element simulations of the cooling by this temperature drop ΔTeff