The Peak Stress Method to assess the fatigue strength of steel welded joints

Giovanni Meneghetti

University of Padova, Department of Industrial Engineering

Davide Marini
University of Padova, Department of Industrial Engineering
EnginSoft SpA, System Dynamics Competence Center

Vittorio Babini
Zamperla SpA

Fatigue strength of welded joints is a crucial aspect in design of mechanical systems and structures. The Peak Stress Method (PSM) is an engineering, FE-oriented method calibrated on Ansys® meshes suitable to assess the fatigue strength of arc-welded steel joints. Based on the Notch Stress Intensity Factors (N-SIFs), the PSM is a CAE method which uses simple, linear elastic FE analyses. The design stresses to assess fatigue failures are the peak stresses obtained at the weld toe or the weld root. The method uses coarse meshes generated automatically by Ansys® numerical code, allowing the application of the NSIF-s approach even in complex three-dimensional FE analyses.

The N-SIFs approach fully takes into account the effects of plate thickness, joint shape and loading mode (axial or bending) so that a single design curve exists to assess fillet-welded joints in steel in as-welded conditions. Therefore, due to its simplicity, the PSM seems to be a useful and robust method in the everyday design practice of the industries. In this paper the effectiveness of the PSM has been successfully tested on full-size welded specimens adopted in amusement rides.