Effect of lay-up sequence on mechanical properties and fracture behaviour 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 effect of the lay-up sequence on the mechanical properties and fracture behavior of the advanced CFRP composite. The mechanical properties were evaluated by three-point slow bend and instrumented Charpy impact tests. Two mm-V notch subsize specimens with angles of 0, 45 and 90 ° between the fibers of the 0 ° layers and longitudinal direction of the specimen ((0 °), (45 °) and (90 °) specimens) were used. The unidirectional laminate (0 °/0 ° ply-(0 °)) specimen exhibited high slow bend and Charpy impact energies, but the 0 °/0 ° plies had a remarkable anisotropy of the mechanical properties. The mechanical properties of the orthotropic laminates (0 °/90 ° plies-(0 °) and (90 °)) specimens significantly decreased but those of the 0 °/90 ° ply-(45 °) specimen dramatically increased. There was a marked benefit in the mechanical isotropy for quasi-isotropic laminates (0 °/90 °/ ±45 ° plies). However, slow bend and Charpy impact energies of the 0 °/90 °/ ±45 ° plies-(0 °), (45 °) and (90 °) specimens were 60 and 70%, respectively, of those of the 0 °/0 ° ply-(0 °) specimen. The results are described and discussed.