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Effect of cooling rate and crack propagation direction on the mode 1 interlaminar fracture toughness of biaxial noncrimp warp‐knitted fabric composites made of glass/PP commingled yarn
Author(s) -
Wang Yantao,
Dong Qingzhi,
Xu Yongjun,
Zhou Shanhua,
Qi Dehai
Publication year - 2008
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.20350
Subject(s) - materials science , composite material , breakage , fracture mechanics , fracture toughness , toughness , bridging (networking) , computer network , computer science
The mode 1 interlaminar fracture toughness of biaxial (±45°) noncrimp warp‐knitted fabric composites made of glass/PP commingled yarn was investigated. The crack propagation along the warp and weft directions, respectively, was considered for the composites cooled at two different rates during laminate molding. The interlaminar fracture toughness was characterized by determining the critical strain energy release rate ( G IC ) of initiation and propagation measured from the double cantilever beam tests. In the case of a slow cooling rate (1°C/min), most specimens possess pure interlaminar crack propagation and direction‐independence characteristics. Nevertheless, the high‐cooled (10°C/min) specimens fractured in both directions suffer extensive intraply damage (crack branching, debonding, and bridging of 45°‐oriented interfacial yarns) and knit thread breakage, leading to G IC of propagation two times higher than that of the slow‐cooled specimens, and the clear difference in the G IC values of initiation between the two directions may be due to the contribution of the knit thread breakage to the fracture energy. POLYM. COMPOS., 2008 © 2007 Society of Plastics Engineers