Kinking and compressive failure in uniaxially aligned carbon fibre composite tested under superposed hydrostatic pressure

• Published in: Journal of materials science 1982-03, Vol.17 (3), p.893-900
• Main Authors: Parry, T. V., Wronski, A. S.
• Format: Article
• Language: English
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/BF00540389

A study was conducted at atmospheric and superposed hydrostatic pressures of up to 300 MN/sq m to characterize failure initiation and propagation in uniaxially-aligned, 60% volume fraction Type III carbon fiber/epoxide compressive specimen that were strained parallel to the fiber axis. Mechanisms involving shear-operated fiber failure are discounted in view of the pressure-sensitivity of the failure process above 150 MN/sq m hydrostatic pressures, and it is found that the initiation of failure in atmospheric tests below that figure is associated with transverse cracking followed by kinking. Groups of fractured fibers were observed ahead of the propagating kink band, consistent with buckling failure that would result in composite catastrophic failure. While splitting and interlaminar cracking was suppressed at higher pressures, kinking remained the initiator of failure. An attempt is made to analyze failure for the case of notched specimens by means of the fracture mechanics model of Chaplin (1979).