NEW STRESS INTENSITY FACTOR SOLUTIONS FOR ANELLIPTICAL CRACK IN A PLATE

摘要

Crack assessment in engineering structures relies first on accurate evaluation of the stress intensity factors.In recent years, a large work has been conducted in France by the Atomic Energy Commission to developinfluence coefficients for surface cracks in pipes. However, the problem of embedded cracks in plates (andpipes) which is also of practical importance has not received so much attention. Presently, solutions for ellipticalcracks are available either in infinite solid with a polynomial distribution of normal loading or in plate, butrestricted to constant or linearly varying tension.This paper presents the work conducted at EDF R&D to obtain influence coefficients for plates containingan elliptical crack with a wide range of the parameters : relative size (2a/t ratio), shape (a/c ratio) and free surfaceproximity (a/d ratio where d is the distance from the center of the ellipse to the closest free surface). Thesecoefficients were developed through extensive 3D finite element calculations : 200 geometrical configurationswere modeled, each containing from 18000 to 26000 nodes. The limiting case of the tunnel crack (a/c = 0) wasalso analyzed with 2D finite element calculation (50 geometrical configurations). The accuracy of the results waschecked by comparison with analytical solutions for infinite solids and, when possible, with solutions forfinite-thickness plates (generally loaded in constant tension).These solutions will be introduced in the RSE-M Code that provides rules and requirements for in-serviceinspection of French PWR components.