PSI - Issue 25

Jamaloddin Jamali et al. / Procedia Structural Integrity 25 (2020) 180–185 Author name / Structural Integrity Procedia 00 (2019) 000–000 opening and its equivalent value of fracture toughness (mode I and mode II components of fracture toughness and effective fracture toughness, ��� ) were calculated. To measure the crack propagation and crack opening a simple tracking method was employed. In both specimen the crack started from the notch tip, in mode I loading the crack followed the along the direction of the notch while in mixed mode loading with angle of α=15° the cracked propagated with an angle of about 7° compared to the notch direction. The value of effective fracture toughness changed from 34.86 MPa √ m for pure mode I to 30.37 MPa √ m mixed mode loading ( α =15). 185 6

Fig. 4 Broken carbon fiber epoxy and the resulting crack propagation direction (a) under mixed mode loading (b) under pure mode I

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