Critical crack tip opening displacement for polymer composites

✍ Scribed by C. Vipulanandan; N. Dharmarajan

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 1017 KB
• Volume: 33
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(89)90090-8

✦ Synopsis

Applicability of critical stress intensity factor (K,) and/or critical crack tip opening displacement (CTODA for epoxy and polyester polymer composites (PC) in mode I fracture are investigated. Both unreinforced and glass fiber reinforced polymer composite systems are studied using single edge notched beams in three-point and four-point bending at room temperature. Crack mouth opening displacement method (CMOD) is used in determining the crack extension during pre-peak loading. The critical stress intensity factor is calculated at the tip of the effective crack and the critical crack extension is represented by the elastic crack tip opening displacement. A simple model has been developed to determine the elastic CTOD from the measured elastic CMOD, and the performance of this model is compared to several other models proposed for metals and cement concrete. The test results indicate that the two fracture parameters are independent of initial notch depth. The two fracture parameters are used in predicting the notch sensitivity of epoxy PC and polyester PC. Resistance curves based on stress intensity factor (&curve) and crack tip opening displacement (Va-curve) have been developed for the 4% glass fiber reinforced polyester PC.