A procedure for fatigue design of web-stiffened cruciform connections

Abstract

Fatigue design of dynamic loaded ship structures is normally based on finite element analysis using shell elements where the welds are not included in the analysis models. Finite element analyses of a fatigue-tested hopper knuckle type specimen were performed for calibration of analysis methodology in a joint industry project. The test specimen was analyzed using solid and shell elements. Only the solid element models included the weld geometry. In the present work, the finite element analyses were extended to other geometries at web-stiffened cruciform joints such as typical found at hopper connections, at stringer heels, and at joints connecting deck structures to vertical members in ship structures. Based on the result from these analyses, a methodology for derivation of hot spot stress at welded connections accounting for the weld size using shell finite element models was developed. The basis for this procedure is presented in this paper.