Evaluation of process-induced residual stresses in orthogonal 3D woven composites via nonlinear finite element modeling validated by hole drilling experiments

Effects of matrix material constitutive model and presence of defects on development of manufacturing induced residual stresses are studied using Finite Element (FE) analysis in an orthogonal 3D woven composite. The residual stresses are assumed to arise from a difference in the coefficients of thermal expansion between the reinforcement and the matrix. Numerical results are compared with experimentally observed surface displacements resulting from blind hole drilling and measured via electronic speckle pattern interferometry. It is demonstrated that for accurate reproduction of the residual stress fields using FE modeling, viscoelastic matrix properties should be used and possible presence of cracks at the tow/matrix interface should not be neglected.