Req ID:530323 

Prediction of Distortion due to Welding in Traction Converters    

Alstom Västerås / RSC Traction Design -  20260910                   

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Background
Alstom’s traction enclosures are made of welded connections. However, conventional design methodologies often overlook or rely on empirical methods to assess the impact of welding on structural integrity. This has, in some cases, resulted in distortion or buckling of the thin-walled aluminum panels due to residual stress from welding. These issues have led to significant redesign efforts and increased overall production costs. To mitigate this, it is essential to predict welding-induced distortions during the concept design phase, thereby reducing the need for redesign later in the development process.                        

Problem description and goals
The thesis project aims to develop a finite element (FE) calculation method for predicting welding-induced distortion. This method integrates welding simulation with structural analysis. The computational approach will be validated through experimental measurements to ensure reliability. Ultimately, the goal is to create a design tool that enables engineers to predict weld distortion early in the development process.

Activities

1. Introduction to traction enclosure mechanical design.
2. Understand Structural requirements of railway vehicle bodies, e.g. EN 12663-1
3. Read and understand the weld modelling methods recommended by literature and across different industries.
4. Welding Simulation: Thermomechanical simulation to determine residual stresses, to be used as loading for structural analysis. Input required : weld geometry and heat input in kJ/mm.
5. Structural Analysis: Using stress distribution from welding simulation to determine the mode & magnitude of the deformation of the structure. This includes:
   1. Small deformation analysis: To scale the weld load from weld simulation to the structural analysis.
   2. Eigen value analysis: Estimate structures critical buckling load & distorted shape.
   3. Incremental large deformation analysis: Determine both critical buckling load and distortion magnitude accurately ( only for validating predictive method)
6. Experimental measurements (if necessary): Blinding hole drilling method to measure residual stress distribution due to welding.
7. Create a design tool to predict weld distortion.

Prerequisites: Background in Mechanical engineering, understanding of structural design, weld joint analysis, familiarity with FEA tools. Good analytical skills and systems thinking mindset.

Type of degree project (can be both)  Language for the thesis       
Master (20 weeks):☒              Swedish:☒ and/or English:☒
Suggested number of students: 1       
Bachelor/Högskoleingenjör (10 weeks): ☐

Is Swedish a language requirement? 
Yes:☐             
No: ☒
No, but Swedish is a requirement for future employment:☐


Possibility to work from our office
Yes:☒
No:☐

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Important to note

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