Study on cure-induced residual stresses and spring-in deformation of L-shaped composite laminates using a simplified constitutive model considering stress relaxation

In this paper, a simplified constitutive model of resin in curing process considering stress relaxation was proposed. The simulation of composite curing using the proposed model is accurate as the simulation using viscoelastic model, but the computing efficiency is greatly improved. The proposed model balances the simulation accuracy and efficiency, which is urgently needed in practice. Then it was utilized to predict the spring-in deformations of L-shaped composite laminates with different structural parameters. The results were in good agreement with the corresponding experiments. A new interpretation of the generation mechanisms of residual stresses and spring-in deformation was presented based on the monitoring of changes of strains and stresses. The simulated results show that the residual stresses and spring-in deformation would be overestimated without considering stress relaxation. The quantitative discussions of the influence mechanisms of different structural parameters, including thickness, corner radius, corner angle and lay-up, were also presented.