Residual Stresses and Warping in Unsymmetric Laminates with Arbitrary Lay-Up Angles
Thermal residual stresses during processing incur the warping of the unsymmetrically laminated composites. While the warping of the cross-ply laminates has been characterized well, general unsymmetric laminates with arbitrary lay-up angles are still not fully understood. This paper presents the formulation which treats the curvatures and principal direction of curvature of the cured shape in unsymmetrically laminated composites. The effect of spatial dependence of in-plane strains on curvatures is significant near the bifurcation point in case of laminates having the stacking arrangement where snap-through phenomenon occurs. It is shown that the principal direction of curvature calculated from classical lamination theory agrees with this theory in the limited range of length-to-thickness ratios of laminates. Curvatures and principal direction of curvature according to the length-to-thickness ratios, the number of layer and lay-up angles of the laminates are presented.
KeywordsResidual Stress Spatial Dependence Bifurcation Point Principal Direction Thickness Ratio
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