Development of an approximate point load weight function for internal circumferential surface cracks in hollow cylinders

Abstract

Internal circumferential surface cracks pose a subtle yet severe threat to the structural integrity of pipes and risers. Accurate determination of stress intensity factors for various surface crack geometries is fundamental to reliable fatigue crack growth life prediction in hollow cylindrical components. In this study, a new approximate point load weight function was developed to calculate mode I stress intensity factors associated with internal circumferential surface cracks in hollow cylinders. The weight function coefficients were calibrated by using the stress intensity factor solutions obtained from parametric three-dimensional finite element models. The derived weight function accommodates a broad range of geometric parameters, including crack aspect ratio, relative crack depth and normalized wall thickness. The verification was conducted by comparing the stress intensity factors obtained from the developed weight function with those calculated using finite element models for both one-dimensional and two-dimensional stress distributions, showing good agreement. The results demonstrate that the derived approximate point load weight function provides reliable computation of stress intensity factors and potentially lays a foundation for fatigue crack growth life assessment for hollow cylinders containing internal circumferential flaws across various loading conditions.