Influence of porosity on the delamination behaviour of glass-fiber reinforced epoxy

JUAN MORÁN; VERA ALVAREZ; ADRIÁN CISILINO

Buenos Aires

Conferencia; VI International conference on science and technology of composite materials, COMAT 2015; 2015

Glass fiber reinforced epoxy composite laminates were prepared by compression moulding. Mechanical properties were determined experimentally by means of uniaxial tensile tests and mode I interlaminar fracture. Delamination onset and growth was modelled using FEM. The models assumed a perfect interfacial material and mode-I crack path propagation that follows a line of cohesive elements placed along the specimen symmetry plane. However, it was observed that the real crack path is irregular, and it deviates from the symmetry plane. This phenomenon was attributed to porosity in the interface material. Porosity was characterized by optical microscopy and digital image analysis techniques. The crack path was characterized by contact profile measurement. Simple analytical models were proposed to account for the effect of the porosity itself, and the irregular crack path it induces. Results showed that the phenomena have counterbalancing effects: while porosity reduces the effective crack propagation area, the irregular crack path increases it. Porosity might have a higher impact in model results than the irregular crack path.