Fracture Characteristics of Angleplied Laminates Fabricated from Overaged Graphite/Epoxy Prepreg

A series of angleplied graphite/epoxy laminates was fabricated from overaged prepreg and tested in tension to investigate the effects of overaged or “advanced-cure” material on the degradation of laminate strength. Results which include fracture stresses indicate a severe degradation in strength. In addition, the fracture surfaces and microstructural characteristics are distinctly unlike any features observed in previous tests of this prepreg and laminate configuration. Photographs of the surface and microstructures reveal flat morphologies consisting of alternate rows of fibers and hackles. These fracture surface characteristics are independent of the laminate configurations. The photomicrographs are presented and compared with data from similar studies to show the unique characteristics produced by the overaged prepreg. Analytical studies produced results which agreed with those from the experimental investigations.