Abstract
<title>Abstract</title> <p>Cure-induced deformation is a major source of dimensional deviation in thin-walled curved composite parts. Its prediction remains challenging because tool–part interaction can couple interfacial restraint with cure shrinkage and shear-lag deformation. This study develops an analytical model for predicting cure-induced spring-in of curved composite parts by explicitly incorporating tool–part interaction. The interfacial restraint is introduced into the equilibrium equation as a bounded frictional shear stress, leading to a closed-form solution that accounts for rubbery-stage through-thickness shrinkage, longitudinal constraint under generalized plane strain, shear-lag deformation, and tool–part friction. The proposed solution is validated against experimental data from the literature for AS4/8552 unidirectional and cross-ply curved parts and further compared with finite element simulations. The model captures the observed thickness dependence of spring-in with satisfactory accuracy, with prediction errors of 5.9% for the cross-ply curved part and 11.5% for the unidirectional curved part. Friction activated only after vitrification has little influence on the final spring-in angle, whereas rubbery-stage friction reduces spring-in, especially for thin parts. A thin-limit approximation is also derived for rapid assessment. The proposed model provides a physically interpretable and efficient tool for predicting cure-induced spring-in in thin-walled curved composite structures.</p>