A lberto Visentin

Abstract

In fatigue design of welded structures, the Peak Stress Method (PSM) is a FE-oriented tool to estimate the Notch Stress Intensity Factors (NSIFs). In compliance with proper design curves validated against more than 1300 experimental data, the PSM allows to estimate the fatigue lifetime of welded structures made of aluminium alloys or structural steels and subjected to uniaxial and multiaxial constant amplitude (CA) as well as variable amplitude (VA) loads. Moreover, an interactive analysis tool has also been developed in Ansys^® Mechanical in order to automate PSM application on welded structures and support the FE analyst. In this work, the fatigue strength of complex steel tube-plate welded joints with reinforcement ribs has been experimentally investigated under bending, torsion and in-phase as well as out-of-phase combined bending and torsion CA as well as VA loads. The specimen consists of a steel SHS tube having 6.3 mm thickness, which is joined at both ends to a 15-mm-thick plate. In addition, tube and plates are joined by fillet welding to 6-mm-thick steel reinforcement ribs. A test rig has been designed in order to perform the experimental fatigue tests, taking advantage of two 15 kN MTS hydraulic actuators. The test program involves six series of CA tests in the fatigue life range 5·10⁴ ÷ 2·10⁶ cycles, each series consisting of six specimens. Additional specimens are being tested under uniaxial as well as multiaxial VA loads. The experimental fatigue results have been compared with fatigue lifetime estimations performed using the automated PSM tool.

Session