Bonding

The objective of this study has been to increase the fracture toughness of multi-layer continuous-filament graphite-epoxy composites. The method used is intermittent interlaminar bonding, which can lead to a large in-crease in the fracture surface area. In this study we achieved intermittent bonding through introduction of thin perforated Mylar between the layers of the composite. For the best optimum condition included in this study, fracture toughness was increased from about 100 kJ/m2 for untreated specimens to an average of about 500 kJ/m2, while tensile strength dropped from 500 MPa to 400 MPa, and elastic modulus remained the same at about 75 GPa. An approximate analysis is presented to explain the observed improvement in toughness