Closed-form solution for process-induced stresses and deformation of a composite part cured on a solid tool: Part II – Curved geometries

In this study, closed-form expressions are developed that provide insight into the mechanisms that lead to the stress development in curved composite parts undergoing autoclave processing. Despite many assumptions that are made in the course of the analytical development, the closed-form predictions agree well with the more sophisticated finite element results. It is shown that stresses in a curved part develop mainly due to the thermo-chemical strain mismatch between the part and the tool in the tangential and radial directions. The unbalanced moment which causes the deformation due to the thermo-chemical strain mismatch in the tangential direction develops mostly at the early stages (heat-up) of the curing process when the part shear modulus is very low compared to its axial modulus. In contrast, the unbalanced moment due to the thermo-chemical strain mismatch in the radial direction develops mostly at the final stages (cool-down) of the cure cycle when the part shear modulus is relatively high.