A portion of a flawed thin-walled shell with an elliptical-arc external surface flaw located in a straight zone (pipe) or in a joint zone (elbow) is analysed to evaluate stress field and fatigue life. Such a portion is assumed to be a part of a shell of revolution, described by two principal curvature radii (R1 and R2). By employing the superposition principle and the power series expansion of the actual stresses, an approximated stress-intensity factor (SIF) expression can be determined for different actual loading conditions. In the present paper, the SIFs (weight functions) for five elementary stress distributions are determined through a FE analysis, by varying the relative curvature radius of the shell from 0 to infinity. Then, the SIFs for cylindrical and spherical shells under various loading conditions are computed through the above weight functions. Finally, a numerical simulation is carried out to predict the crack growth under cyclic internal pressure with constant amplitude. Some results are compared with those determined by other authors.
Fatigue behaviour of surface-cracked shells / Carpinteri, Andrea; Brighenti, Roberto; Spagnoli, Andrea. - (2000), pp. 431-438. (Intervento presentato al convegno XV Convegno Nazionale del Gruppo Italiano Frattura IGFXV tenutosi a Bari).
Fatigue behaviour of surface-cracked shells
CARPINTERI, Andrea;BRIGHENTI, Roberto;SPAGNOLI, Andrea
2000-01-01
Abstract
A portion of a flawed thin-walled shell with an elliptical-arc external surface flaw located in a straight zone (pipe) or in a joint zone (elbow) is analysed to evaluate stress field and fatigue life. Such a portion is assumed to be a part of a shell of revolution, described by two principal curvature radii (R1 and R2). By employing the superposition principle and the power series expansion of the actual stresses, an approximated stress-intensity factor (SIF) expression can be determined for different actual loading conditions. In the present paper, the SIFs (weight functions) for five elementary stress distributions are determined through a FE analysis, by varying the relative curvature radius of the shell from 0 to infinity. Then, the SIFs for cylindrical and spherical shells under various loading conditions are computed through the above weight functions. Finally, a numerical simulation is carried out to predict the crack growth under cyclic internal pressure with constant amplitude. Some results are compared with those determined by other authors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.