Metal Forming: Formability, Simulation, and Tool Design

Front Matter
Copyright
Dedication
Contributors
Preface
Acknowledgements
Introduction
	Further reading
Formability
	Introduction
	Deformation-zone geometry
	Voids and void-growth mechanisms
	Fractography and fracture
	Uncoupled ductile damage criteria and fracture
		Link between uncoupled ductile damage and fracture mechanics
			Mode I-Tensile fracture
			Mode II-In-plane shear fracture
			Mode III-Out-of-plane shear fracture
			Graphical representation of the analytical framework for ductile damage
		Uncoupled ductile damage and the Lode parameter
			Uncoupled ductile damage criterion due to Isik (2018)
			Uncoupled ductile damage criterion due to Bao and Wierzbicki (2004)
	Coupled ductile damage criteria and fracture
		Micromechanics-based damage criteria
		Macromechanics-based approaches
	Experimental determination of the fracture loci
		Sheet metal forming
		Bulk metal forming
	Plastic instability
		Diffuse necking in uniaxial tension
		Localised necking in uniaxial tension
		Localised necking in biaxial tension and the forming limit curve
		Representation of the forming limit curve in principal strain space
		Factors influencing the forming limit curve
		Representation of the forming limit curve in space of effective strain vs stress triaxiality
	Experimental determination of the forming limit curve
	Process defects
		Rolling
		Forging
		Wrinkling in deep drawing
		Tube bending
	Metallurgy
		Crystalline structure
		Defects
		Material matrix
		Grain size
		Surface quality
	References
Finite element simulation: A user’s perspective
	Introduction
	The finite element environment
	Mesh generation
		Structured vs unstructured meshes
		Mesh generation techniques
			Mapped meshing
			Sweeping
			Plastering
			Indirect meshing
			Grid-based meshing
	Nonlinearity in finite element modelling of metal forming
	Kinematics of large deformations
		Measures of strain
		Rate of deformation
		Measures of stress
	Finite element formulations
		Quasi-static finite element formulations
			Direct iterative method
			Newton-Raphson iterative methods
			Convergence criteria
			Finite element equations
			Pros and cons of quasi-static finite element formulations
		Dynamic finite element formulations
			Explicit integration using the central difference method
			Pros and cons of explicit dynamic formulations
	Errors in finite element analysis
		Modelling errors
			Analysis type
			Material models
			Fundamental physical phenomenon
			Material data
			Ductile damage
			Friction and heat transfer
			Description of tooling
			Machine tools
		Numerical errors
			Selection of elements
			Discretisation and mesh convergence
			Time step and convergence criteria
			Other factors
		Other errors
	Validation of finite element procedures
		Process-independent validation procedures
			Material flow
			Stress field
			Distribution of forces
			Convergence studies
		Process-dependent validation procedures
			Validation against theoretical solutions and technical data available in literature
			Validation against experimental and industrial observations and measurements
	References
Finite element flow formulation
	Introduction
	Theoretical fundamentals
		Quasi-static equilibrium-A solid mechanics view
		Second extremum principle-An energy view
			Rates of energy
			Extremum principles
		Momentum balance equation-A fluid dynamics view
			Viscous fluids
			Differential momentum balance equation
	Discretisation by finite elements
	Iterative solution methods
		Direct iterative method
		Newton-Raphson iterative method
		Line search algorithms
	Explicit solution scheme
	Numerical integration
	Treatment of rigid zones
	Treatment of friction
	Contact between objects
		Linear contact algorithms
		Penalty-based contact algorithms
		Lagrange multiplier-based contact algorithms
		Contact between deformable objects
	Thermo-mechanical analysis
		Heat transfer equation
		Finite element discretisation
	Electro-thermo-mechanical analysis
	Extensions of the conventional finite element flow formulation
		Porous metals
		Ductile polymers
		Viscous flow
		Anisotropic metals
			Rotation between global axes and material axes
		Elastic effects
	References
Introduction to the finite element solid formulation
	Introduction
	Theoretical fundamentals
	Discretisation by finite elements
	Implicit vs explicit integration procedures
	Rate-independent limit
	References
Tool design
	Introduction
	Tools for compressive forming
		Open-die tools
		Impression-die tools (closed-die tools)
		Precision tools
			Conventional precision tools
			Precision tools with floating dies
			Precision tools with multidirectional dies
	Tools for tensile, combined tensile and compressive forming, and bending
		Conventional tools with single-station dies
		Multidirectional tools with single-station dies
		Progressive tools with multistation dies
	Tools for forming by shearing
		Combination tools
		Compound tools
		Fine blanking tools
	Tool materials
		Selection of tool materials
		Hardening and tempering
		Surface treatments and coatings
		Preheating of punches and dies
	Punches
		Punch dimensioning
		Punch design
	Dies
		Die dimensioning
			Lamé equations
			Monoblock
			Prestressed container-Stress rings
			Guidelines for dimensioning a prestressed container with one stress ring
			Guidelines for dimensioning a prestressed container with two stress rings
			Manufacture of die cores and stress rings
			Strip-wound container
			Die design
			Rod and tube extrusion dies
			Can extrusion dies
	Lubrication
	Tool failure
		Wear to out-of-tolerance conditions
		Catastrophic failure (fracture)
		Thermal softening and subsequent deformation of dies
		Insufficient polishing of the punches and dies
		Inaccurate dies that miss target dimensions
		Material choice for punches
	References
	Further reading
Appendices
	Appendix A
		Algebraic decomposition of the stress triaxiality
	Appendix B
		Large elastic-plastic and rigid-plastic deformations
	Appendix C
		Mathematics for continuum mechanics
	Appendix D
		Force increment ratio that is necessary for an elastic element to yield (Yamada et al., 1968)
	Appendix E
		Basic cold forging processes
	Appendix F
		Calculation of deflections and stress distributions in the die core and stress rings
		Assembly of die and stress ring
		Operation of die and stress ring during the extrusion process
		Unloading before ejection of the workpiece
		Unloading after ejection of the workpiece
	Appendix G
		MATLAB computer program
		Listing of the MATLAB computer program
	Appendix H
		Fit recommendations (adapted from Fisher et al., 2008)
	References
Index
	A
	B
	C
	D
	E
	F
	G
	H
	I
	K
	L
	M
	N
	O
	P
	Q
	R
	S
	T
	U
	V
	W