Session: 03-03-02: Damage, Fatigue, and Fracture

Paper Number: 106841

106841 - Fatigue Life Prediction of Unidirectional Cfrp Specimen Based on Micro-Scale Mechanical Field 

A methodology of fatigue life prediction for Carbon Fiber Reinforced Plastic (CFRP) structural members has been investigated in rational manner to refer fatigue strength property of resin. We employ micro-scale model, in which carbon fiber and resin are simulated separately to introduce their material properties directly. We pose an assumption that the fatigue life of CFRP is governed by that of resin. The micro-scale analysis of CFRP to evaluate mechanical field seems to yields a new perspective of fatigue life prediction method with the posed assumption.

Uni-directional tensile fatigue tests were performed on resin and uni-directional CFRP specimens whose carbon fiber orientations deviate 30°, 45°, 60°, and 90° from the loading axis. Numbers of loading cycles to failure deviate much in terms of nominal maximum stress of the specimens.

Owing to adequate setting of periodic boundary condition, we can get precise mechanical field of resin between fibers. We have searched for adequate mechanical variables, such as the first principal tress, Tresca stress, von Mises stress and so on, to predict fatigue life of the CFRP specimens in relation with fatigue life of resin.

Finally, we conclude that the fatigue life of the CFRP specimen is successfully predicted by means of the interfacial normal stress (INS), which is the normal stress on a plane perpendicular to the line segment connecting the center axes of two carbon fibers. Deviation of numbers of cycles to failure becomes small for CFRP specimens, and the numbers are adequately predicted by the result of fatigue test of resin in terms of INS.

Presenting Author: Yoshikawa Nobuhiro The University of Tokyo

Presenting Author Biography: Academic Degrees:
1990 Doctor The University of Tokyo
Thesis Field: Mechanical Engineering
1987 Master The University of Tokyo
Thesis Field: Mechanical Engineering
1985 Bachelor The University of Tokyo
Thesis Field: Mechanical Engineering

Academic Appointments:
2005 – present Professor
Institute of Industrial Science
The University of Tokyo
1994 – 2005 Associate Professor
Institute of Industrial Science
The University of Tokyo
1992– 1994 Lecturer
Institute of Industrial Science
The University of Tokyo
1990 – 1992 Research Associate
Institute of Industrial Science
The University of Tokyo

Authors:

Yoshikawa Nobuhiro The University of Tokyo
Naoki Morita University of Tsukuba
Yuka Sahara The University of Tokyo
Masahiro Hojo Japan Aerospace Exploration Agency