Welding Deformation and Residual Stress Prevention

Welding Deformation and Residual Stress Prevention
Copyright
Preface
	References
List of symbols
Acknowledgments
Appendix
	References
Author biography
Introduction to welding mechanicsa
	Chapter outline
	Introduction to welding process, distortion, and residual stress
	Production process of residual stress and its source (inherent strain)
		Illustrative model
			Temperature distribution in a welded joint
			Temperature distribution and mechanical constraint
			Idealized model
			Thermal elastic-plastic analysis
		Model under no constraint; heating of free Bar C (restraint condition )
		Model fixed at both ends; heating of Bar C fixed at both ends (restraint condition )
			Low-temperature heating
				Heating stage (heating from T=0CTmaxTY)
				Cooling stage (cooling from TmaxTY to 0C)
			Medium-temperature heating
				Heating stage
				Cooling stages
			High-temperature heating
				Heating stage (heating from T=0C to 2 TYTmax, i.e., stress point 0 to P, Fig. 1.18)
				Cooling stages
		Model under general contraint; heating Bar C when it is connected to a movable rigid body (restraint condition )
			Low-temperature heating
				Heating stage (heating from T=0CTmaxTY)
				Cooling stage (cooling from TmaxTY to 0C)
			Medium-temperature heating
				Heating stage (heating from T=0CTYTmax2TY)
				Cooling stages
			High-temperature heating
				Heating stage (heating from T=0C to 2 TYTmax, i.e., stress point O to P, Fig. 1.18)
				Cooling stages
	Reproduction of residual stress by inherent strain and inverse analysis for inherent strain
		Reproduction of residual stress by inherent strain
		Inverse analysis for inherent strain
	Numerical examples of residual stress, inherent strain, and inherent deformation
		Low-temperature heating process (TmaxTY, process , Fig. 1.21, also refer to Fig. 1.16)
			Heating stage (0CTmax C)
			Cooling stage (Tmax C0C)
		Medium-temperature heating (process , Fig. 1.21, TYTmax2 TY, also refer to Fig. 1.17)
			Heating stage (0CTmax C)
				Cooling stage (Tmax C0C)
		High-temperature heating (process , Fig. 1.21, Tmax2TY, also refer to Fig. 1.18)
			Heating stage (0CTmax)
			Cooling stage
	References
Introduction to measurement and prediction of residual stresses by the inherent strain method
	Chapter outline
	Inherent strains and resulting stresses
		Displacement-strain relation (compatibility)
		Stress-strain relation (constitution equation)
		Equilibrium condition (equilibrium equation)
	Measured strains in experiments and inherent strains
	Effective and noneffective inherent strains
	Determination of effective inherent strains from measured residual stresses
	Most probable value of effective inherent strain and accuracy of the measurement of residual stress
	Derivation of elastic response matrix
	Measuring methods and procedures of residual stresses in two- and three-dimensional models
		Measurement of two-dimensional residual stresses induced in the butt-welded joint of a plate
		Measurement of three-dimensional residual stresses induced in thick plates
	Prediction of welding residual stresses
	References
Mechanical simulation of welding
	Chapter outline
	Heat flow and temperature during welding
		Heat supply, diffusion, and dissipation
		Simple heat flow model
			Change of temperature distribution with time (without heat transfer)
			Change of temperature distribution with time (with heat transfer)
			Influence of heat input
			Influence of speed of heat input
			Influence of plate thickness
			Influence of heat conduction
			Influence of heat transfer
		Differences in material properties
		Change of material properties with temperature
		Characteristic temperature and length
			Metallurgical melting temperature
			Mechanical melting point
			Yield temperature
			Highest temperature reached
			Cooling speed
			Resolution required for computation
		Simple method for solving the heat conduction problem
		Summary
	Basic concepts of mechanical problems in welding
		Classification of problems according to dimensions
		Variables and equations used to describe mechanical problems
		Deformation and stress in the three-bar model
			Strain-displacement relation
			Stress-strain relation
			Equilibrium equation
		Stress-strain relation in welding
			Strains to be considered in a welding problem
				Decomposition of strain increment
				Thermal deformation and thermal strain increments
				Elastic deformation and elastic strain increments
				Plastic deformation and plastic strain increments
				Creep deformation and creep strain increment
			Incremental stress-strain relation in welding problem
		Thermal visco-elasto-plastic problem in three-bar model
			Strain-displacement relation
			Stress-strain relation
			Equilibrium equation
				Computation of displacement, strain, and stress increments
				Computation of total displacement, strain, and stress
		Closing remarks
	References
Computing methods of welding thermal-mechanics
	Chapter outline
	Welding heat source models
		Concentrated heat source models and their theoretical solutions
		Distributed heat source models for heat conduction analysis
			Goldak heat source model for arc welding
			Simple Gauss-distributed heat source model
			Uniform heat source model with arbitrary molten zone
			Surface heat source model
			Combination of various heat source models
	Basic thermal conduction and heat transfer equations
		Basic differential equations
		Finite element equation and conventional implicit method
		Newton-Raphson explicit method
	Finite element method for welding thermal stress and strain
		Displacement and its increment
		Stress, strain, and their increments
		Definition of various strains in thermal stress analysis
			The total strain and its increment
			The elastic strain and its increment
			Plastic strain and its increment
			The thermal strain and its increment
			Phase transformation strain and its increment
			The creep strain and its increment
		Stress update formula under thermal elastic-plastic loading state
			General formula for thermal stress update
			Thermal stress update under thermal elastic state
			Thermal stress update under thermal elastic-plastic loading state
			Thermal stress update under thermal elastic-plastic state with phase transformation
			Thermal stress update under thermal elastic-plastic state with creep strain
		Implicit FE formulation for welding thermal elastic-plastic analysis
		Explicit FE formulation for welding thermal elastic-plastic analysis
	Introduction of advanced material models
		Isotropic hardening and kinematic hardening
		Advanced modeling in multipass welding thermal stress
	Simulation procedures and checkpoints
		Simulation flow
		Input data preparation
			Check list for preparation of input data
			Consistent use of units
		Checklist for the results of simulation
			Checklist for both heat conduction analysis and stress analysis
			Checklist for results of heat conduction analysis
			Checklist for result of thermal elastic-plastic analysis
		Troubleshooting the problems experienced in computation
			Troubleshooting common problems in heat-conduction analysis and stress analysis
			Troubleshooting for heat conduction analysis
			Troubleshooting for thermal elastic-plastic analysis
	References
Residual stress in typical welded joints
	Chapter outline
	Basic thermal elastic-plastic-creep behavior in a fixed bar model
		Bar fixed at both ends under a thermal cycle
		Thermal elastic behavior of a bar fixed at both ends
		Thermal elastic-plastic behavior of a bar fixed at both ends
		Thermal elastic-plastic creep behavior of a bar fixed at both ends
	Residual stress distribution in single-pass bead-on-plate welds
		Residual stress induced by welding
		Influence of postweld heat treatment on welding residual stress
		Effect of size on shape of residual stress distribution
	Residual stress distribution in lap joints
	Residual stress distribution in a thick-plate butt-welded joint
	Residual stress distribution in pipe butt-welded joints
		Residual stress distribution in a thin-walled pipe joint
		Residual stress distribution in a medium thick-walled pipe joint
		Influence of repair welding on residual stress distribution in a medium thick-walled pipe joint
	Residual stress distribution in a multipass P92 steel joint
		Modeling of Satoh test
		Influence of SSPT and multithermal cycle on formation of residual stress
		Comparison between simulation results and measured data
	Residual stress distribution in a thick-plate fillet joint
	Features of residual stress distribution near weld end-start location
	Closing remarks
	References
	Further reading
	Glossary
Practical analysis methods for welding deformation of structures
	Chapter outline
	Practical numerical methods
		Shell model and elastic analysis
		The inherent strain method
		The inherent deformation method
		The interface element
		Evaluation of inherent deformation
	Welding deformation prediction
		Structure model
		Gravity and supports
		Treatment of gaps and misalignments resulting from welding
		Processing results and drawing conclusions
		Analysis example: Prediction of welding deformation of a simple structure
	Reduction of welding deformation by straightening
		Introduction
		Theory
		FE-TEPA analysis of gas line heating process
		High-order integration element for inherent strain of line heating
	References
	Further reading
Prediction of structural welding deformation and its mitigation
	Chapter outline
	Welding deformation of a small construction model
		Model descriptions
		Welding deformation analysis by thermal elastic-plastic FEM
		Welding deformation analysis by inherent deformation-based elastic FEM
		Mitigation of welding deformation by setting jig constraints close to weld lines
	Welding assembly deformation of a train structure model
		Description of train structure model
		Inherent deformation database
		Calculated welding assembly deformation
	Prediction of welding deformation of a road bridge girder
		Considered girder structure
		Assembly sequence
		Finite element model
		Inherent deformation, analysis, and results
	Prediction and mitigation of welding deformation of a seagoing ferry superstructure block using the inherent deforma ...
		Prediction of welding deformation
			Assembly sequence
			FEM model
			Boundary conditions and loading
			Materials
			Welding conditions
			Inherent deformation
			Analysis and results
		Mitigation of welding deformation
	Prediction of welding deformation of ships deckhouse structure and its mitigation
		Model descriptions
		Fabrication procedure and analysis conditions
			Stage I: Block assembly
			Stage II: Erection and fitting
			Stage III: Mitigation (straightening)
		Numerical results
			Stage I: Block assembly
			Stage II: Erection and fitting
			Stage III: Mitigation (straightening)
	References
Analysis of additive manufacturing residual stress and deformation
	Chapter outline
	Introduction
	Toward large-scale simulation of residual stress and distortion in additive manufacturing
		Advanced computing methods
		Efficient grouping techniques
	Residual stress and distortion in WAAMed thin wall models
		Descriptions of models
		Residual stress and deformation in a 4-layer thin wall model
		Residual stress and deformation in a 20-layer thin wall model
	Residual stress in WAAMed aluminum alloy specimen
		WAAM specimen
		Finite element modeling
		AM deformation and residual stress
	Residual stress in laser-deposited functionally graded material layers
		Descriptions of laser-deposited functional graded material (FGM) layers
		Residual stress in laser-deposited functionally graded material layers
		Effect of material properties on residual stress in FGM layers
			Effect of material properties on residual stress in one-layer model
			Effect of material properties on residual stress in two-layer model
			Effect of material properties on residual stress in two FGM layer model
	Residual stress and strain due to solid-state cold spray additive manufacturing
		CSAM specimen
		Measured residual stresses in CSAM specimen
		Simulation on formation mechanism of CSAM residual stress
	References
Welding mechanics analysis of countermeasures for product performance problems
	Chapter outline
	Cold cracking at the first pass of a butt-welded joint under mechanical restraint
	Cold cracking of slit weld
	Analysis of welding residual stress of fillet welds for prevention of fatigue cracks
		Residual stresses using three-dimensional analysis
		Comparison of residual stresses by two-dimensional and three-dimensional analyses
		Comparison of residual stresses in single-pass and multipass welds
	Multipass-welded corner joints and weld cracking
		Experiment and result
		Residual stresses by thermal elastic-plastic analysis
		Effects of welding residual stress and geometry of edge preparation on initiation of welding cracks
	Analysis of transient and residual stresses of multipass welding of thick plates in relation to cold cracks, under-b ...
		Specimens and conditions for theoretical analysis
		Characteristics of welding residual stress distributions and production process
			Condition B
			Condition A
	Improvement of residual stresses in a circumferential joint of a pipe by heat-sink welding
	Analysis of welding deformation and residual stress of automotive parts
	Fatigue crack propagation analysis considering welding stress
		Application target and test conditions
		Welding thermal elastic-plastic analysis
		Fracture mechanics analysis
		Evaluation of fatigue life considering the change in welding heat input
	Analysis of buckling strength considering welding deformation and residual stress
		FE model of a stiffened panel structure
		Welding deformation and residual stress
		Buckling analysis considering welding deformation and residual stress
	Methods to control deformation due to cutting and welding before structure assembly
		Cutting
		Welding
			In-plane transverse deformation of one-sided automatic welding
			Out-of-plane deformation caused by FCB butt welding
	References
Index
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	H
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	Q
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