An Explicit Method to Calculate the Stress Intensity Factor of Round Bar With Mode I Crack Under Arbitrary Stress Distribution

The processing of barbs in sutures introduces cracks, reducing the fracture resistance of the barbed sutures. Obtaining stress intensity factor (SIF) is pivotal for the optimal design and safe usage of barbed sutures. In this study, an explicit method was proposed to calculate the SIFs for a barbed suture with Mode I crack under arbitrary stress distribution. The barbed suture was modeled as a round bar with different shapes of Mode I cracks. The shape coefficient, which was defined to describe the shape of crack, was computed using the point load weight function. Based on these shape coefficients, the basic stress intensity factors (BSIFs) for cracks under basic stress distributions, such as uniform, linear, and quadratic stress distributions, were determined. Then, the SIFs under arbitrary stress distributions were calculated through linear superposition of these BSIFs according to the corresponding stress distribution. The relative errors between the SIFs calculated by this method and the finite element are commonly within ± 8%. This demonstrates that the proposed explicit method is capable of directly and accurately calculating SIFs for round bars with Mode I cracks under arbitrary stress distributions, thereby avoiding the time-consuming processes of finite element analysis and numerical integration.