Experimental and analytical validation of mode II fracture toughness tests for a type of double-lap joint. (15th February 2020)

• Record Type: Journal Article
• Authors: Oshima, Sota; Yoshimura, Akinori; Yashiro, Shigeki; Hirano, Yoshiyasu; Ogasawara, Toshio
• Is Part Of: Composite structures. Volume 234(2020)
• Publication Date: 2020-02-15
• Subjects: Polymer matrix composites -- Fracture mechanics -- R-curve tests -- Toughness testing -- Delamination; Composite construction -- Periodicals; Composites -- Périodiques; 624.18
• DOI: 10.1016/j.compstruct.2019.111757
• Languages: English
• ISSNs: 0263-8223

Abstract

Abstract: Mode II fracture toughness tests for a type of double-lap joint referred to as the doubly end notched tension (DENT) tests were validated by experimental and numerical approaches. Crack growth behavior of two cracks was simultaneously observed during fracture toughness tests and analyzed by the digital image correlation (DIC) method. As one of the two cracks propagated first and the other followed, finite element (FE) analyses were carried out to clarify the mechanisms. The results of FE analyses showed that mode II energy release rate at the extended crack tip increased at the beginning of crack growth, and subsequently decreased under constant displacement condition. An opposite trend was found at the other crack tip. One cause of this phenomenon was due to local bending of the specimen. The effects of the geometry of specimens were also discussed. The FE analyses also revealed that the ratio of middle layer thickness to the outer layers thickness significantly affects the crack growth behavior in the DENT specimens.