Process influence on fracture toughness of new generation carbon-epoxy laminates

This paper concerns an attempt to manufacture a RTM laminate in such way that its mechanical properties are similar to that of a new generation autoclave processed carbon fiber reinforced plastic. High toughness properties have been achieved for this 3^rd generation composite material. This results from the inclusion of thermoplastic phases in the prepreg tapes. To obtain such composite improvement by means of the RTM process, dry carbon fiber layers were prepared with a specific lay up of thermoplastic particles. The present study compares the fracture behavior of both composite materials which may be regarded as quasi equivalent. Before performing mechanical tests, initial stress states are estimated by monitoring the cure processes with embedded optical fiber Bragg gratings. Then, inter laminar shear strength tests and fracture tests in mode I and II are carried out. Results show slightly better overall performances of the RTM manufactured material. However, process parameters need particularly fine adjustments before achieving an acceptable quality of laminate.