The effect of the fiber/matrix interface on the flexural fatigue performance of unidirectional fiberglass composites

• Published in: Composites science and technology 1987, Vol.28 (2), p.137-161
• Main Authors: Shih, G.C., Ebert, L.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Forms of application and semi-finished materials; Polymer industry, paints, wood; Reinforced plastics; Technology of polymers
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/0266-3538(87)90095-9

Fatigue tests were conducted on oriented fiberglass-reinforced polymer matrix composites using four-point bending with a stress ratio of −0·8. Composites in which the fiberglass was treated with a commercial diaminofunctional silane coupling agent were found to possess a relatively high flexural fatigue performance compared with composites without coupling agents. Using the interlaminar shear strength as an indication of the interface strength, it was found that composites having a high interface strength possess a high fatigue performance. The failure sequence of the flexural (tensile) fatigue was identified as: nucleation and growth of superficial damage (including fiber ridging, transverse matrix cracking, longitudinal matrix cracking, fiber breaking and local delamination), sudden fiber-bundle breakage and, finally, macroscopic delamination. A strong interface between fiber and matrix delayed the occurrence of fiber ridging and longitudinal matrix cracking, thus improving the fatigue performance of the unidirectional composites.