Mixed-Mode Fracture of Inclined Straight-Fronted Edge Cracks in Round Bars: Stress Intensity Factors and Propagation Criteria for Suture Design

Abstract

Barbed sutures revolutionize surgical wound closure by eliminating knots and ensuring uniform stress distribution, yet barb cutting introduces inclined straight-fronted edge cracks that compromise fracture resistance. This study addresses this critical limitation by developing an equivalent model of barbed sutures, incorporating key geometric features, and employing three-dimensional finite element analysis with the contour integral method to compute mixed-mode stress intensity factors (SIFs) along the crack front. We systematically investigate the interplay between cutting parameters—depth ratios and angles—and SIFs for Modes I, II, and III, revealing how deeper cuts and higher angles exacerbate crack propagation risks. Equivalent SIFs, derived from maximum tangential stress and maximum potential energy release rate criteria, pinpoint the crack front's midpoint as the most vulnerable site, with empirical equations enabling rapid predictions. These findings offer actionable insights for optimizing barb design to balance anchoring strength and fracture toughness, enhancing suture reliability in clinical settings and informing fracture mechanics in cylindrical structures. This work bridges biomedical engineering and fracture theory, providing theoretical support for the development of safer and more effective surgical tools.