Study on the delamination behavior of thick composite laminates under low-energy impact

In order to study the delamination of thick composite laminates under low-energy impact, damage prediction and analysis were presented in this paper. The impact tests were carried out on specimens with three kinds of stacking sequence under three energy levels, and followed by the nondestructive tests to obtain the delamination region. Then numerical models were built to simulate the delamination behavior of composite laminates. The simulation results showed a good correlation to the experimental observations. Furthermore, delamination characteristics in plane and its extension through thickness direction were put forward. The delamination shape was found enclosed by Archimedes spiral and the fiber direction of the layer above and below. The delamination location was limited by the impact zone and the fiber distribution. In the thickness direction, the extension area was found decreased layer by layer. Moreover, the characteristics above were revealed through the analysis of damage mechanism. Finally, the verification of the predicted results was presented based on experiments. The realization of delamination prediction may contribute to evaluating residual strength and optimizing airplane structures.