Method for determination of continuous fibers reinforced composite delamination resistance in bending of beams with lateral transverse notch

Important strength characteristics of fiber-reinforced composites with polymer matrix include their resistance to delamination and splitting, which is traditionally determined in bending of short beams (in terms of interlayer shear strength) or specimens with artificial delaminations (in terms of critical energy release rate, i.e., specific work of delamination). The implementation of these techniques is associated with known difficulties in interpretation and comparison of results. The method of determining the critical value of the stress intensity factor at the occurrence of delamination crack near the apex of the transverse layer notch is proposed in this paper. It allows: to compare the crack resistance of various composites and metals, to estimate the potential strength of unidirectional fiber-reinforced composites at fracture by the mechanism of multiple splitting, to formulate the requirements of «equal strength» under the condition of simultaneous occurrence of different types of fracture. Experimental results on the resistance to delamination of composites with different reinforcement schemes in terms of the critical stress intensity factor at crack rotation and their comparison with the interlayer strength of the material are presented.

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