Fatigue Behavior and the Relationship Between Crack Propagation and the Slit Configuration of C/C Composites

Abstract

The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber laminates with α = 0/90 • direction were investigated. Also, the phenomenon of crack growth behavior and the shear damage in the fiber bundle was discussed. Slits of several sizes were cut on both sides of a test section and different sizes of slit length were chosen. The effect of the slit configuration on crack initiation and growth behavior was observed. Specimens with blunt-notches and center-holes were also used to compare the fatigue strength and crack growth behavior. Non-propagating cracks were observed and fatigue limit was defined as the maximum stress at which specimen did not break for N = 10 7 cycles stress application. The longest fatigue life was obtained in the case of specimens with shorter slits. The relationships between fatigue strengths and specimen shapes were analyzed by stress concentration, Kt, and stress intensity factor, K I . The effect of slit configuration on fatigue strength was then discussed regarding both the experimental and calculated consequences.

Notch Sensitivity on Fatigue Behavior of Carbon-Carbon Composites

“…It actually acts like a plain specimen. The damage in the matrix was expanded in large area, the fatigue limit σw became lowest in the case of blunt notched specimens [1,2]. The share deformation and succeeding broken behavior of carbon fiber is related to the fiber constraint [3][4][5][6].…”

An evaluation of fatigue limit of notched specimen of a C/C composite

“…The carbon fiber including resin was sintered for carbonizing the resin. That was called the carbon fiber reinforced carbon compound composites or C/C composites [1][2][3][4][5][6].…”

“…Also, the effects of notch root radius on fatigue behavior of some notched specimens was investigated [6]. In this paper, we review the results of those studies and some discussion about the qualitative tendency of a fatigue limit of a C/C composite of machine-able type was performed.…”