Contact indentation of marine composites

Quasi-static indentation tests on low fibre-volume, hand-produced, E-glass/polyester 'marine' laminates have been performed. A Hertzian contact law fitted well the initial response. Considerable material variability was seen in the Hertzian behaviour of the woven roving tests. The presence of an irregular resin-rich surface was influential at initial contact and was thought to reduce the contact stiffness for smaller diameter indenters. At higher loads the response became linear as damage became significant. The transition to linear behaviour is thought to be due to delamination. Good correlation of the transition load with indenter radius was obtained using a simplified shear delamination model. Despite their significantly lower fibre-volume, chopped strand mat laminates exhibited a slightly higher contact stiffness than woven roving laminates.