Role of interlaminar deformation mismatch in cure-induced stress evolution and distortion response of CFRP laminates

Cure-induced residual stress and distortion critically affect the dimensional accuracy and service performance of autoclave-cured carbon fiber reinforced polymer (CFRP) laminates. However, the role of interlaminar deformation mismatch in residual stress and distortion remains insufficiently quantified. A three-dimensional sequentially coupled thermo–chemo–mechanical finite element model was developed, and interlaminar deformation mismatch was quantified from differences in stress-free thermal and cure-shrinkage strains between adjacent plies using a scalar mismatch index. The model accounts for cure exotherm, viscoelasticity, ply anisotropy, tooling constraints, and demolding, and its predictions agree well with published benchmark results. During cooling, the deformation mismatch between the 0° and 90° plies increases from about 5 × 10 −3 to above 12 × 10 −3 , contributing to a marked increase in the local through-thickness stress, which reaches approximately 27 MPa. For [ 0 / θ / θ / 0 ] laminates, the mismatch index increases with θ , thereby contributing to the corresponding increase in peak residual stress, whereas laminate–tool friction and curing pressure have limited effects on the overall stress distribution. Free-boundary effects promote local stress concentration, while unbalanced through-thickness mismatch in asymmetric laminates promotes warpage after demolding. These results identify interlaminar deformation mismatch as a dominant mechanism contributing to cure-induced residual stress and distortion.