Observing the Failure of Open-Hole CFRP specimens in Tensile Tests

Introduction

Offering superior specific strength, even compared to other composite materials, carbon fiber reinforced plastic (CFRP) is used in aircraft and some transport vehicles for the purpose of saving fuel through weight reduction. Composite materials have excellent mechanical properties. However, a general feature of composite materials is that their strength decreases markedly when they are notched. CFRP is no exception, so tests of notched specimens are important. In this case, testing is performed using specimens notched with a circular hole at the center. In this experiment, tensile tests were performed using CFRP specimens (laminate method [45/0/-45/90]_2s) with a total length of 150 mm, a width of 36 mm, and a thickness of 2.5 mm, prepared with a 6 mm circular hole at the center. The failure process of the CFRP specimens was observed during the tensile tests. In particular, it is important to confirm the failure process of weak regions, such as the periphery of circular holes, for CFRP development and to confirm the validity of CAE analysis. However, since the failure of CFRP is a brittle phenomenon, where failure occurs instantaneously, it cannot be confirmed with the naked eye. For this reason, high-speed video cameras are used to observe the failure. In this experiment, synchronized images were obtained at the front and the side of the specimens using two HPV-X2 high-speed video cameras.

July 16, 2015 GMT