Control of Welding Distortion in Thin-Plate Fabrication

The intense temperature fields caused by heat sources in welding frequently lead to distortions and residual stresses in the finished product. Welding distortion is a particular problem in fabricating thin plate structures such as ships. Based on pioneering research by the authors, Control of Welding Distortion in Thin-Plate Fabrication reviews distortion test results from trials and shows how outcomes can be modeled computationally. The book provides readers with an understanding of distortion influences and the means to develop distortion-reducing strategies.

The book is structured as an integrated treatment. It opens by reviewing the development of computational welding mechanics approaches to distortion. Following chapters describe the industrial context of stiffened plate fabrication and further chapters provide overviews of distortion mechanics and the modeling approach. A chapter on full-scale welding trials is followed by three chapters that develop modeling strategies through thermal process and thermo-mechanical simulations, based on finite-element analysis. Simplified models are a particular feature of these chapters. A final sequence of chapters explores the simulation of welding distortion in butt welding of thin plates and fillet welding of stiffened plate structures, and shows how these models can be used to optimize design and fabrication methods to control distortion.

Control of Welding Distortion in Thin-Plate Fabrication is a comprehensive resource for metal fabricators, engineering companies, welders and welding companies, and practicing engineers and academics with an interest in welding mechanics.

• Allows practitioners in the field to minimize distortion during the welding of thin plates
• Provides computational tools that can give insight into the effects of welding and fabrication procedures
• Demonstrates how welding distortion in thin plate fabrications can be minimized through design

Metal fabricators; Forensic engineers; Engineering companies involved in the fabrication and manufacture of metal-end products; Engineers and academics with an interest in metallurgy and welding

Author contact details

Woodhead Publishing Series in Welding and Other Joining Technologies

Preface

1. Introduction: development of computational welding mechanics approach to welding distortion

Abstract:

1.1 Background: control of welding distortion in fabrication practice

1.2 Aims: integrated design approach utilising computational welding mechanics (CWM)

1.3 Structure of the book

1.4 Conclusion

1.5 References

2. Fabrication of stiffened thin-plate structures and the problem of welding distortion

Abstract:

2.1 Introduction

2.2 Welding distortion of stiffened-plate and other fabricated structures

2.3 Outline of a typical fabrication process

2.4 Raw materials and primary process factors

2.5 Management issues relevant to thin-plate distortion

2.6 Rectification of thin-plate distortion

2.7 Conclusion

2.8 References

3. Tools to deal with welding distortion: predictive modelling and research on in-process techniques

Abstract:

3.1 Introduction

3.2 Artificial neural networks (ANNs)

3.3 Computational simulation

3.4 Current research on reduction of distortion

3.5 Conclusion

3.6 References

4. Understanding welding distortion: thermal fields thermo-mechanical effects

Abstract:

4.1 Introduction

4.2 Thermal fields: dependence on welding parameters and material properties

4.3 Thermo-mechanical effects

4.4 Thermo-mechanical treatment based on longitudinal–transverse uncoupling

4.5 Plane strain strip: longitudinal deformations and forces

4.6 Transverse welding deformations

4.7 Residual stress

4.8 Buckling

4.9 Conclusion

4.10 References

5. Computational simulation of welding distortion: an overview

Abstract:

5.1 Introduction

5.2 Multi-physics

5.3 Thermal property non-linearity

5.4 Phase change and non-linear thermal dilatation

5.5 Mechanical property idealisation

5.6 Thermal computation outline

5.7 Range of thermo-mechanical approaches available

5.8 Reduced solutions and their advantages

5.9 Conclusion

5.10 References

6. Experimental investigation of models of welding distortion: methods, results and comparisons

Abstract:

6.1 Introduction

6.2 Importance of experimental observations

6.3 Welding process application in test work

6.4 Thermocouple arrays

6.5 Thermography

6.6 Deformation measurement

6.7 Completion and smoothing of measured deformation profiles

6.8 Characterising out-of-plane deformation

6.9 Conclusion

6.10 References

7. Modelling thermal processes in welding

Abstract:

7.1 Introduction

7.2 Convection and radiation

7.3 Heat input modelling

7.4 Simulation of weld deposition

7.5 Thermal property non-linearity

7.6 Three-dimensional transient thermal computation

7.7 Transient finite-element model based on two-dimensional cross-section

7.8 Thermal computation in stiffener fillet weld geometries

7.9 Welding efficiency

7.10 Thermal cutting

7.11 Conclusion

7.12 References

8. Computationally efficient methods for modelling welding processes

Abstract:

8.1 Introduction

8.2 Computationally efficient methods based on algorithms

8.3 Hybrid stepwise solution methods

8.4 Conclusion

8.5 References

9. Finite-element thermo-mechanical techniques for welding distortion prediction

Abstract:

9.1 Introduction

9.2 Formulation of thermo-mechanical finite-element model

9.3 Case study: influence of tacking procedures on butt-weld distortion

9.4 Case study: fillet-welded stiffened plate

9.5 Conclusion

9.6 References

10. Simulating welding distortion in butt welding of thin plates

Abstract:

10.1 Introduction

10.2 Plate support and out-of-flatness influences

10.3 Effects of tacking

10.4 Clamping effects

10.5 Residual stress in butt welds

10.6 Multiple butt welds

10.7 Conclusion

10.8 References

11. Simulating welding distortion in fillet welding of stiffened plate structures

Abstract:

11.1 Introduction

11.2 Plates with double-sided continuous fillet-welded single stiffeners: thermal aspects

11.3 Plates with double-sided continuous fillet-welded single stiffeners: computationally efficient thermomechanical treatment

11.4 Multiply-stiffened plates: case study on welding sequence

11.5 Conclusion

11.6 References

12. Exploiting welding distortion models: examples of design and manufacturing strategies to optimise fabrication

Abstract:

12.1 Introduction

12.2 Optimising multi-stiffener configuration

12.3 Optimising the design in terms of weld position

12.4 Limiting heat input to avoid buckling

12.5 Simulation of transient thermal tensioning: fabrication-related distortion reduction study

12.6 Simulated use of low-transformation-temperature filler material to reduce distortion

12.7 Simulated use of weld-trailing cryogenic cooling process to reduce distortion

12.8 Conclusion

12.9 References

Index