Studying Failure Modes of GFRP Laminate Coupon Specimens Using Scanning Electron Microscopy Technique

Abstract

Fiber-reinforced plastics (FRPs), with their unique material and structural properties, offer many advantages over conventional structural materials such as concrete and steel. However, their brittle failure mechanisms at the ultimate stage make them difficult for use in important structural applications. When it comes to glass FRP (GFRP) bridge deck systems, due to the existence of various configurations of structural elements and the nonavailability of acoustic emission (AE) monitoring standards, the need for further exploration of damage identification for the unique configurations adopted in field bridges has become a necessity. The GFRP laminate coupon samples originating from a new FRP-balsa wood composite bridge built in Louisiana were investigated to obtain insight into their structural performance and possibly assess damage mechanisms. In order to assess the critical failure modes in the GFRP laminate samples, three separate sets of specimens were prepared to initiate certain damage mechanisms, and several tests were carried out under varied load conditions to study the critical failure modes such as fiber breakage, matrix cracking, and delamination. Those tested specimens were then examined using the scanning electron microscopy (SEM) technique to identify the failure modes through material changes at the microlevel. Acoustic emission sensors were also installed to collect AE data for further study.