Influence of the 90/0 ply thickness ratio on the stresses associated with the edge effect phenomenon

The scale effect phenomenon has shed light on the thermo-mechanical behaviour of ultra-thin plies. These laminas in cross-ply laminates (under certain 90/0 thickness ratios) have given rise to a relevant edge effect phenomenon, causing significant through-the-thickness stress in the weakest ply along its free edge under both thermal and (0-longitudinal tension) mechanical loading. Thus, a biaxial stress state must be considered to analyse what happens along the free edges from experimental samples to structural components, such as drill holes. A parametric numerical analysis is performed taking three different features into account: the thickness of the ply blocks, the cross-ply stacking sequences and the type of fibre, either carbon or glass. The numerical predictions are in accordance with experimental results, which are obtained under a thermal cooldown. The biaxial stress state predictions could be used in future numerical procedures including the presence of components’ free edges.