Fracture toughness evolution of a carbon/carbon composite after low-cycle fatigue. (1st February 2019)

• Record Type: Journal Article
• Authors: Stepashkin, A.A.; Ozherelkov, D.Yu.; Sazonov, Yu.B.; Komissarov, A.A.
• Is Part Of: Engineering fracture mechanics. Volume 206(2019)
• Page Start: 442
• Page End: 451
• Publication Date: 2019-02-01
• Subjects: Carbon/carbon composites (CCCs) -- Compression fatigue -- Low cycle fatigue -- J-Integral; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2018.12.018
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: C/C composites show good resistance to compression fatigue loads. Manufacturing defects dramatically reduce fatigue limit of the C/C composites. Fracture toughness of C/C strongly affects by the strength of fiber–matrix interface. Cyclic load below fatigue limit weakens fiber–matrix interface of C/C composites. Weakening of fiber–matrix interface increase the fracture toughness of C/C. Abstract: High fracture resistance of carbon/carbon (C/C) composites as a material for aircraft braking systems is essential for their safe service. This paper presents a study on fatigue behavior and residual mechanical properties after cyclic load of discretely-reinforced C/C composite. The influence of cyclic loads on the fracture toughness of frictional C/C composite was examined. Results of fracture toughness tests after compression fatigue load were determined using the ASTM single-notch three point bend test and correlated with fracture surface using scanning electron microscopy (SEM). It is revealed that C/C composite fracture toughness strongly depends on the fiber–matrix interfacial bonding strength. Cyclic loads below fatigue limit improve residual fracture toughness of the material up to 25% by the mechanism of interfaces weakening. Cyclic loads above fatigue limit decrease residual fracture toughness of the material by the fracture of carbon fibers. Observed results may be useful in developing friction C/C composites to enhance fracture resistance in aircraft braking systems, increasing safety and operating lifetime.