Strain Rate Effects on Mode I Fracture of Unidirectional Carbon Fiber Composites

Abstract: Unidirectional carbon fiber composites were subjected to the Iosipescu shear test under static and low velocity impact conditions (LVI). Specimens were cut for 00 and 900 test configura-tions. Static tests were carried out on a hydraulically activated MTS loading frame, where specimens were subjected to uniform straining. LVI tests were con-ducted on a drop tower facility. The shear response of the specimen was measured for both 00 and 900 specimen configurations. Strain rate effects on interfacial crack tough-ness were also measured. Pre-notched unidirectional stitched carbon fiber specimens were subjected to a static and LVI three point bend test. The crack propagation velocity was measured with the help of special crack propagation gages and a high resolu-tion digital camera. Load vs. load point displace-ment was measured for every test. The effect of strain rate on fracture toughness was characterized.