Welding Deformation and Residual Stress Prevention

Preface

1 Introduction to welding mechanics

1.1 Basic knowledge on welding and mechanics

1.2 Production process of residual stress and its source inherent strain

1.2.1 Presentation of illustrative models

1.2.2 Heating of a free bar

1.2.3 Heating of a bar fixed at both ends

1.2.4 Heating of center bar of three bar model

1.3 Reproduction of residual stress by inherent strain and inverse analysis for inherent strain

1.3.1 Reproduction of residual stress by inherent strain

1.3.2 Inverse analysis of inherent strain

1.4 Numerical examples of residual stress, inherent strain, and inherent displacement

2 Measurement and prediction of residual stresses by inherent strain method

2.1 Relation between inherent strains and resulting stresses

2.2 Relation between measured residual stresses and inherent strains

2.3 Effective and non-effective inherent strains

2.4 Estimating method of effective inherent strains

2.5 Estimating method of effective inherent strains from measured stresses with error

2.6 Derivation of elastic response matrix

2.7 Measuring methods of residual stresses in 2-D and 3-D by inherent strain method

2.7.1 Measurement of 2-D residual stresses induced in a butt weld joint of plate

2.7.2 Measurement of 3-D residual stresses induced in a but joint of thick plate

2.8 Prediction of welding residual stresses by inherent strain method

3 Basic knowledge on simulation analysis for welding thermal process, stress and

deformation

3.1 Basic knowledge for welding thermal process

3.1.1 Heat source, heat conduction and heat transfer

3.1.2 Basic models for welding thermal process

3.2 Basic knowledge for mechanics

3.2.1 Classification of the problem by the degree of dimension

3.2.2 Variables and equations to express mechanical phenomena

3.2.3 Deformation and stress in three bar model

3.2.4 Thermal elastic-plastic behavior of a three bar model

3.2.5 Closing remarks

4. Basic Concept of Finite Element Method

4.1 Finite Element Method, Powerful tool for variety of problems

4.2 Types of problem and corresponding basic equations

4.3 Basic knowledge for the principle of variation

4.4 How to solve a problem composed of plural elements

4.5 Incremental method for non-linear problems

4.6 Examples of analyses of basic problems on thermal elastic-plastic creep behavior

4.6.1 Bar fixed at both ends under a thermal cycle

4.6.2 Thermal elastic behavior of a bar fixed at both ends

4.6.3 Thermal elastic-plastic behavior of a bar fixed at both ends

4.6.4 Thermal elastic-plastic creep behavior of a bar fixed at both ends

4.7 Basic theoretical solutions to testify the results provided by FEM

4.7.1 Temperature distribution due to concentrated heat source

4.7.2 Temperature distribution of butt welded joint of thin plate

4.7.3 Temperature distribution of butt welded joint of thick plate

4.7.4 Inherent strain distribution of butt welded joint of thin plate

4.8 Flow of analysis for welding deformation and residual stress

4.9 Check list for rational simulation

4.9.1 Check list for preparation of input data

4.9.2 Check list for the results of simulation

4.10 Trouble shooting for the problems experienced in computation

5 Questions and Answers of attached FEM programs

5.1 Basic information of attached FEM program

5.2 Welding thermal conduction FEM program

5.3 Welding thermal elastic plastic creep FEM program

5.4 Inherent strain FEM program

5.5 Post processing program

5.6 Descriptions of sample data for FEM simulation

6 Experience simulation using attached FEM programs

6.1 Experience simulation using welding heat conduction FEM program

6.1.1 Simulation model and conditions

6.1.2 Creation of input data

6.1.3 Execution of welding heat conduction FEM program

6.1.4 Graphic view and discussion of simulation results

6.2 Experience simulation using welding thermal-elastic-plastic-creep FEM program

Simulation model and conditions

6.2.1 Creation of basic input data

6.2.2 Creation of temperature history file

6.2.3 Execution of welding thermal-elastic-plastic-creep FEM program

6.2.4 Graphic view and discussion of simulation resul

6.3 Experience simulation using welding inherent strain FEM program

6.3.1 Simulation model and conditions

6.3.2 Creation of input data

6.3.3 Execution of welding inherent strain FEM program

6.3.4 Graphic view and discussion of simulation results

6.4 Experience simulation on stress measurement using welding inherent strain FEM program

6.4.1 Stress measurement model and conditions

6.4.2 Creation of input data

6.4.3 Execution of welding inherent strain FEM program

6.4.4 Graphic view and discussion of simulation results

6.5 Experience simulation on stress prediction using welding inherent strain FEM program

6.5.1 Stress prediction model and conditions

6.5.2 Creation of input data

6.5.3 Execution of welding inherent strain FEM program

6.5.4 Graphic view and discussion of simulation results

7 Simulation Analysis of welding stresses and deformation for manufacturing problems

Forewords

7.1 Cold cracking at the first pass of butt welded joint under mechanical restraint

7.2 Cold cracking of slit weld

7.3 Analysis of welding residual stress of fillet welds for prevention of fatigue cracks

7.4 Multi-pass welded corner joints and weld cracking

7.4.1 Method of experiment and the result

7.4.2 Residual stresses estimated by thermal elastic-plastic analysis

7.4.3 Effects of welding residual stress and geometry of edge preparation on initiation of

welding cracks

7.5 Analysis of transient and residual stresses of multi-pass butt welds of very thick plates in

relation to cold cracks, under-bead cracks

7.5.1 Specimens and conditions for theoretical analysis

7.5.2 Characteristic of welding residual stress distributions and production process

7.6 Improvement of residual stresses of circumferential joint of pipe by heat-sink welding

7.7 Prediction of deformation produced by line heating

7.8 Simulation of spot welding

7.9 Simulation analysis of welding deformation of large structures

Appendix

Appendix A Tables and figures of welding residual stresses in various welded joints

Appendix B Temperature dependent material properties and samples for FEM simulation

Appendix C Three dimensional mathematical equations for thermal elastic plastic creep

phenomena

List of FEM Programs