Characterization and modelling of spring-in effect on Z-shape composite part

International audienceIn this study, a simple finite-element model is developed to predict the spring-in of Z-section composite parts made of carbon fiber/ epoxy resin manufactured with resin transfer molding process. The different mechanisms occurring during manufacturing and effective in the formation of residual stresses and shape distortions are implemented. They are mainly the thermal effect and the chemical shrinkage of the resin during the cross-linking polymerization reaction. A dedicated experimental procedure allowing separation of strains to cure shrinkage and thermal expansion is presented to characterize the resin cure shrinkage. Cure kinetic properties of the resin are determined with differential scanning calorimetry measurements. The spring-in angles predicted by the finite element analysis are compared to the angles measured on the Z-section specimens of various thicknesses