The "free-corner effect" in thermally loaded laminates

The occurrence of localized high interlaminar stresses is a well-known phenomenon along the free edges of composite laminates, which is called "free-edge effect". Beyond the generally considered situation of a straight free laminate edge, a more specific but also very important situation is that of a free rectangular laminate corner. Here the localized occurrence of interlaminar stresses can be named as "free-corner effect". For this free-corner effect an approximate closed-form description is given for a class of relatively simple laminates subjected to thermal loading. The applied approach makes use of an equilibrium stress distribution and the principle of minimum complementary energy to describe the situation in the laminate corner region. The predicted interlaminar stress distribution at the ply interfaces is shown to be in good agreement with comparative 3-dimensional finite element analyses.