Using the Stress Concentration Factor in Determining the Fracture Toughness

Abstract

This paper offers the use of stress concentration factor in determining the critical fracture stress and fracture toughness of polymeric composite materials at various crack length ratios. The stress intensity factor has been turned into a function of the stress concentration factor derived from the maximum stress occurring at the notch tip and the tip stress generated by the force applied to the sample. This conversion allowed the use of a fixed theoretical radius 1.2732 mm instead of the actual radius of the notch or crack. On the edge cracked three-point bending and tensile samples, the specified method detects the three-point bending fracture stresses with a maximum error rate of 1.2 %. This study also establishes a relationship between the clamped end and the pin-loaded tensile specimens and states that the underlying mechanism of the stress intensity factor of the clamped end tensile specimen is based on the normalization of the stress intensity factor of the pin-loaded conditions with the geometric correction factor.