Paper number 362

EFFECTS OF TEST CONDITIONS ON MODE II INTERLAMINAR FRACTURE TOUGHNESS OF FOUR-POINT ENF SPECIMENS

Kazuro Kageyama¹, Isao Kimpara¹, Toshio Suzuki¹, Isamu Ohsawa¹, Makoto Kanai¹ and Hitosh Tsuno¹

1Department of Environmental and Ocean Engineering, University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Summary

Mode II interlaminar fracture toughness of laminated composites has risen importance to design criteria and material selections for advanced composite structures. Recently, Martin and Davidson have proposed four-point ENF (4ENF) test, which requires no special control system or complex loading fixture. In the present paper, effects of test conditions, such as specimen dimensions, loading conditions, friction between delamination surfaces, and data reduction methods on Mode II interlaminar fracture toughness at initiation and during delamination growth have been discussed by experimentally and theoretically. An improved test procedure and new data reduction method have been proposed based on the results and discussions. The 4ENF test has been considered one of the candidates of international standard test method for Mode II interlaminar fracture toughness.

Keywords

interlaminar fracture toughness, delamination, mode II, 4 points ENF, energy release rate, friction, standardization.