Stress Concentration Solution for a 2D Dent in an Internally Pressurized Cylinder

Abstract

Dent imperfections in internally pressurized shells have a stress concentration effect. In cylindrical shells under internal pressure, such as pipelines, stress concentrations associated with dent imperfections can degrade in-service performance. A new semianalytical solution is developed for the stress concentration distribution present along the two-dimensional circumferential cross section of a cylinder under internal pressure containing a local dent-like imperfection. An equivalent load approach is used. Results are compared against finite-element results. For practical application, the stress concentration factor (SCF) present at the outer surface of the dent center is derived. Parametric studies with this expression show that long dent stress concentrations are primarily influenced by the dent depth-pipe thickness and the dent depth-pipe diameter ratios. Example cases show that SCF values between 10.0 and 20.0 are possible and that even shallow dent SCFs can be above 2.0.