EFFECT OF LAY-UP SEQUENCE ON MECHANICAL-PROPERTIES AND FRACTURE-BEHAVIOR OF ADVANCED CFRP LAMINATE COMPOSITE

Long carbon fibers with 5.5 GPa in average tensile strength-reinforced epoxy plastic laminates (CFRP) have been studied to determine the eff ect of the lay-up sequence on the mechanical properties and fracture b ehavior of the advanced CFRP composite. The mechanical properties were evaluated by three-point slow bend and instrumented Charpy impact tes ts. Two mm-V notch subsize specimens with angles of 0, 45 and 90 degre es between the fibers of the 0 degrees layers and longitudinal directi on of the specimen ((0 degrees), (45 degrees) and (90 degrees) specime ns) were used. The unidirectional laminate (0 degrees/0 degrees ply-(0 degrees)) specimen exhibited high slow bend and Charpy impact energie s, but the 0 degrees/0 degrees plies had a remarkable anisotropy of th e mechanical properties. The mechanical properties of the orthotropic laminates (0 degrees/90 degrees plies-(0 degrees) and (90 degrees)) sp ecimens significantly decreased but those of the 0 degrees/90 degrees ply-(45 degrees) specimen dramatically increased. There was a marked b enefit in the mechanical isotropy for quasi-isotropic laminates (0 deg rees/90 degrees/+/- 45 degrees plies). However, slow bend and Charpy i mpact energies of the 0 degrees/90 degrees/+/- 45 degrees plies -(0 de grees), (45 degrees) and (90 degrees) specimens were 60 and 70%, respe ctively, of those of the 0 degrees/0 degrees ply-(0 degrees) specimen. The results are described and discussed. (C) 1997 Elsevier Science S. A.