Stress concentration around perforations produced by corrosion in steel storage tanks

Abstract

This paper presents numerical results of stress concentration factors for plates perforated by corrosion. Evidence from 25 plates with corrosion perforation considered show that typical shapes may be characterized as a deviation from an ellipse or from a circle. In order to model typical perforations created by this type of corrosion, holes with non-circular boundaries have been considered in the form of cosine shape and variations from it. Two load cases are investigated: uniaxial and shear stress fields in an elastic plane stress problem. The influence of the amplitude of deviation with respect to an ellipse or circle and the local curvature of the internal boundary of the hole are studied. A simplified model of an equivalent ellipse originally proposed by Nishida is shown to provide good estimates for stress concentration factors for a range of shapes induced by corrosion.

Controlled Pre-Corrosion Attack and Ultrasonic Fatigue Endurance of Titanium Alloy Ti-6Al-4V

“…In a recent work has been investigated the stress concentration around perforations produced by corrosion in steel storage tanks (Godoy et al 2014); which points out that the irregular profiles of pitting can approach an elliptical perforation with two principal parameters: the number n of "grooves" or "waves" at the inner boundary of the perforation (cosine boundary and star-like boundary), and the deviation "d" of the cosine or star-like at the inner boundary. The principal conclusion is that the stress concentration factor tends to highest values when the number of waves "n" increases, under uniaxial and shear loading.…”

Numerical simulation of the double pits stress concentration in a curved casing inner surface

“…Numerical simulation using finite element analysis (FEA) is an effective method for analyzing this problem. 13,14 Numerical simulation of stress concentrations of double pits in a curved surface…”