Fatigue behavior and lifetime distribution of impact-damaged carbon fiber/toughened epoxy composites under compressive loading

• Published in: Advanced composite materials Vol. 22; no. 2; pp. 65 - 78
• Main Authors: Ogasawara, Toshio, Sugimoto, Sunao, Katoh, Hisaya, Ishikawa, Takashi
• Format: Journal Article
• Language: English
• Published: Routledge 01.04.2013
• Subjects: Carbon fiber reinforced plastics; Carbon-epoxy composites; compression; Compressive properties; fatigue; Fatigue (materials); Impact damage; low-velocity impact damage; Mathematical models; Polymer matrix composites; statistical analysis; Strength; Weibull distribution
• ISSN: 0924-3046; 1568-5519
• DOI: 10.1080/09243046.2013.768324

This paper presents fatigue lifetime data of impact-damaged carbon fiber/toughened epoxy composites under compressive loading to elucidate the lifetime prediction methodology based on statistical approaches. Drop-weight impact damage was induced to a composite specimen with impact energy of 6.7 J/mm in accordance with ASTM D7136. Postimpact fatigue tests were conducted using a test fixture defined in ASTM D7137 under compression-compression loading (R = 10) at room temperature. The maximum compressive stress (S min ) was 200, 210, 220, 230, and 240 MPa, and the total number of specimens was 31. The compression-after-impact strength and fatigue lifetime show considerable scattering. This result is apparently derived from the variation in impact damage size. A simple statistical model based on the weakest link theory was proposed for predicting the lifetime of impact-damaged composite laminates. Results show that the experimentally obtained data were confirmed consistently using this model. The ratio between the endurance limit at 10 6 and 10 7 cycles and the initial static strength was estimated as 0.74 and 0.68 as B-basis allowable values.