STRESSES AND DEFORMATIONS INDUCED DURING MANUFACTURING .1. THEORETICAL-ANALYSIS OF COMPOSITE CYLINDERS AND SHELLS

Composite cylinders and cylindrical shells are important structural me mbers. It has been observed that during the manufacture of these compo nents, residual stresses build up. In composite cylinders, the state o f residual stresses may lead to defects such as micro-cracking, fibre waviness, delamination, and wrinkling, which might degrade the final m echanical performance of the cylinders. In the case of cylindrical seg ments, the residual stresses also lead to a reduction in the enclosed angle where the out-of-plane contraction is higher than the in-plane c ontraction. This phenomenon (of the reduction in the enclosed angle) i s referred to as spring-in. In this paper, a simple mechanics-based mo del is developed using modified shell theory that predicts the degree of spring-in in anisotropic cylindrical shells and determines the resi dual stresses, strains and displacements in both anisotropic laminated composite cylinders and shells with arbitrary lay-ups subjected to ra ndom temperature gradients. The model accounts for the resin shrinkage occurring during curing and also includes the effect of moisture grad ients. The effects of various factors such as geometry of the componen t, the ply stacking sequence, the part thickness and the tool radius a re examined. The accuracy of the present analysis is investigated by c omparing predicted results with previously published results.