Abstract

In automotive industry, the FE fatigue analysis of mechanical structures made of steel thin walled parts and seam welded assemblies uses a dedicated technique based on shell element modelling for components and on 1D rigid elements for welds. This method has been validated with several intensive fatigue test campaigns using gas metal arc welded samples with different assemblies, for both bending and torsional loads. The fatigue results are relative to crack initiation at the weld toe with bending normal stress or with longitudinal shear stress for several load ratios. The purpose of the current work is the transposition of the initial method to another FE welded model. In a recent IIW guideline for the assessment of weld root fatigue, a shell element weld model has been proposed for seam weld fatigue assessment in case of weld root crack initiation. The idea is to analyse the possible extension of this FEA weld element model for weld toe fatigue analysis and several comparisons of stress results are detailed and discussed. Different fatigue criteria are used to verify the correlation with the fatigue test results. First, the approach is based on maximum shear stress, then structural stress is calculated and results are compared to IIW S/N curves.

Highlights

  • The FE fatigue analysis of mechanical structures made of steel thin walled parts and seam welded assemblies uses a dedicated technique based on shell element modelling for components and on 1D rigid elements for welds [1, 2]

  • The stress tensor components are calculated at the weld toe location and the fatigue assessment is performed using a Dang Van maximum shear criterion

  • In a recent IIW guideline for the assessment of weld root fatigue [3], a shell element weld model has been proposed for seam weld fatigue assessment in case of weld root crack initiation

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Summary

Introduction

The FE fatigue analysis of mechanical structures made of steel thin walled parts and seam welded assemblies uses a dedicated technique based on shell element modelling for components and on 1D rigid elements for welds [1, 2]. The stress tensor components are calculated at the weld toe location and the fatigue assessment is performed using a Dang Van maximum shear criterion. This method has been validated with several intensive fatigue test campaigns using gas metal arc welded samples with different assemblies, for both tensile, bending and torsional loads. The fatigue results are relative to crack initiation at the weld toe with bending normal stress or with longitudinal shear stress for several load ratios. The reports of those test campaigns contain all accurate details useful for a numerical correlation. The idea is to analyse the possible extension of this FEA weld element model for weld toe fatigue analysis

Weld FE Models
Model 2
Fatigue specimens and stress analysis
Loading conditions
Hot spot location
Load and boundary conditions
Mean stress effect
IIW structural stress comparison
Findings
Conclusions
Full Text
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