Investigation of damage surface in CFRP under biaxial loading
Tanaka Kohhei; Kanagawa Yasushi; Murakami Sumio
Abstract:Internal damage evolution of thin tubular specimens of CFRP was studied by means of AE (acoustic emission) measurement. The AE signals were detected first in the tension tests of CFRP tubular specimens of 0 degree , 90 degree and +-45 degree fiber orientation, and three damage modes induced by the tests, i.e., matrix crack, delamination and fiber breakage were identified by the frequency analysis of AE signals. Then, tension-torsion tests of specimens of +-45 degree were performed, and the behavior of damage development in every damage stage was analyzed from the frequency analysis of AE signals. AE count rate was also measured in order to detect the onset and the development of material damage. The change in the elastic properties were related to the AE count rate. Then, by performing damage tests under biaxial loading, the initial and subsequent damage surfaces were identified by use of AE count rate. Key Words:CFRP, damage, damage surface, acoustic emission, biaxial stress, loading condition, matrix crack, delamination