THE LAW OF SIMILARITY ON THE FRACTURE-BEHAVIOR OF CONTINUOUS FIBER-REINFORCED COMPOSITE LAMINATES WITH DIFFERENT PLY THICKNESSES

The macroscopic fracture behavior of composite laminates is now being clarified to be controlled by the extension of microscopic cracks. On the basis of released elastic strain energy accompanied by microcrack extension, we present simple equations which enable us to predict the fracture behavior of the laminate with arbitrary ply thickness by usin g the experimental results of the laminate with standard ply thickness . We come to the conclusion that the damaged region ahead of notch tip s in laminates extends to a size proportional to the ply thickness und er the same apparent critical stress intensity factor. The difference in the maximum apparent critical stress intensity factor sustained by the laminate with different ply thicknesses is also quantitatively exa mined. The predicted fracture behavior is in good agreement with the e xperimental results of continuous glass fiber-reinforced epoxy cross-p ly laminates with three different ply thicknesses.