An acoustic emission study of stress corrosion in a chopped strand mat gfrp composite

Abstract

Acoustic emission ( ae) is used to detect stress corrosion damage as it occurs in an E-glass chopped strand mat-reinforced polyester resin. AE activity is observed when samples under tension, having exposed cut edges, are subjected to an environment of either sulphuric acid, which mainly corrodes the fibres, or acetone which degrades the resin. In water there is negligible ae, showing that the acid corrosion ae originates from chemical attack, rather than merely physical penetration of aqueous solution. Linear location of ae signals proves to be an efficient means of determining the onset of stress corrosion cracking in acid, while the ae amplitude distribution is also useful in this respect. In monitoring the growth of stress corrosion cracks in this material in acid it is found that the ae event rate varies with applied stress according to a power law, and there is an approximately linear relationship between the residual strength of the samples and the cumulative total of detected ae events.