MULTIPLE DELAMINATIONS AND THEIR SEVERITY IN CIRCULAR AXISYMMETRICAL PLATES SUBJECTED TO TRANSVERSE LOADING

Instability problem of multiple penny-shape interlaminar delaminations in circular axisymmetric plates subjected to a transverse concentrate d loading is theoretically studied. The authors consider a case that a ll the delaminations located at the same intervals have a same size an d propagate simultaneously. Then, they consider two cases that one of the delaminations is larger or smaller than the rest. The energy relea se rates are obtained in closed forms and the results are compared wit h those obtained numerically via a finite element analysis. The presen t solutions agree excellently with the finite element results. When th e load is constant, the energy release rate is constant regardless of the size of the delaminations and increases linearly with the number o f the delaminations. When one of the delamination is larger or smaller than the others, the energy release rate of the shorter delamination or delaminations become much larger than that of the longer delaminati on(s), that is, only the smaller delamination(s) tends to propagate un til it grows up to the size of the larger delamination(s). Multiple de laminations, if they exist, have a tendency to grow self-similar way.