Evaluation of the effects of preexposure in marine environments of structural glass reinforced composites by acoustic emission testing

Acoustic emission testing (AE) has been used to evaluate the damage progres sion in a glass/polyester woven roving (0/90 degrees) laminate under the co mbined effect of loading and preexposure in an aqueous environment. Four po int bend tests to determine failure and flexural fatigue tests of as receiv ed and preexposed laminates have been carried out accompanied by acoustic e mission recording. Environmental preexposure has been found to alter the da mage progression mechanism in the polyester laminate from predominantly mat rix cracking in the as-received condition to matrix cracking (increased mat rix crack density) plus debonding and delamination after preexposure. Chang es in AE parameters such as hit amplitude and duration were correlated with these changes in failure mode which are supported by microscopic investiga tion.