Cover -- Title Page -- Copyright -- Contents -- Preface -- Chapter 1 Introduction to 4D Printing: Concepts and Material Systems -- 1.1 Background -- 1.2 Overview of 3D Printing Techniques -- 1.2.1 Single-Material 3D Printing Techniques -- 1.2.2 Multi-Material 3D Printing -- 1.3 Shape-Programmable Materials for 4D Printing -- 1.3.1 Shape-Memory Polymers and Composites -- 1.3.1.1 Single SMP -- 1.3.1.2 SMP Nanocomposites -- 1.3.1.3 Printed Active Fiber-Reinforced Composites -- 1.3.1.4 Bilayer SMPs -- 1.3.1.5 Multi-material SMPs -- 1.3.2 Hydrogels and Composites for 4D Printing -- 1.3.2.1 Single-Material Hydrogels and Composites -- 1.3.2.2 Multi-Material Hydrogels -- 1.3.3 Liquid Crystal Elastomers -- 1.3.3.1 Single-Material LCEs -- 1.3.3.2 LCE-Based Multi-Materials -- 1.3.4 Magnetoactive Soft Materials -- 1.3.4.1 Single Magnetoactive Soft Material Composite -- 1.3.4.2 Multi-material MSMs -- 1.4 Modeling-Guided Design for 4D Printing -- 1.5 Summary and Outlook -- Acknowledgments -- References -- Chapter 2 Strategies in 3D Bioprinting of Cell-Laden Bioinks -- 2.1 Introduction -- 2.2 Drop-on-Demand (DOD)-Based Inkjet Printing -- 2.2.1 Introduction to Inkjet Printing -- 2.2.2 Droplet Formation During DOD Inkjetting of Cell-laden Bioink -- 2.2.2.1 Bioink Preparation and Experimental Setup -- 2.2.2.2 Representative Droplet Formation Observations -- 2.2.3 Cell Distribution Within Microspheres During Inkjet-Based Bioprinting -- 2.2.3.1 Effect of Cell Concentration on Cell Distribution -- 2.2.3.2 Effect of Polymer Concentration on Cell Distribution -- 2.2.3.3 Effect of Excitation Voltage on Cell Distribution -- 2.3 Laser Printing -- 2.3.1 Introduction to Laser Printing -- 2.3.2 Effects of Living Cells on the Bioink Printability -- 2.3.2.1 Representative Observations During Laser Printing of Cell-laden Bioink.

2.3.2.2 Effects of Living Cells on Printing Dynamics and Jetting Behaviors -- 2.3.3 Freeform Drop-on-Demand Laser Printing of 3D Alginate and Cellular Constructs -- 2.3.3.1 Overhang Construct Fabrication -- 2.3.3.2 Bifurcated Alginate/Cellular Constructs -- 2.4 Support Bath-Enabled Printing-then-Solidification Extrusion -- 2.4.1 Introduction to Support Bath-Enabled 3D Printing -- 2.4.2 Printing-then-Solidification Extrusion of Alginate and Cellular Structures -- 2.4.2.1 Carbopol-Enabled Two-Step Gelation Approach -- 2.4.2.2 3D Bioprinting of Y-Shaped Tubular Structures -- 2.4.3 Printing-then-Solidification of Liquid Materials in Nanoclay Suspension -- 2.4.3.1 Laponite Utilized as the Support Bath Material for Extrusion Printing -- 2.4.3.2 Gelatin-Based Cellular Construct Fabrication -- 2.5 Continuous Precuring Digital Light Processing (DLP) Printing -- 2.5.1 Introduction to DLP Printing -- 2.5.2 Theoretical Prediction of DLP Working Curve for Photocurable Materials -- 2.5.2.1 Analytical Model of Jacobs Working Curve -- 2.5.2.2 Influence of UV Absorber Concentration -- 2.5.3 Pre-curing Digital Light Processing (DLP) Printing -- 2.5.3.1 The Tunable Pre-curing DLP Printing Approach -- 2.5.3.2 Improving DLP Printing Efficiency by Pre-curing DLP Printing -- 2.5.3.3 Validation of Pre-curing DLP Printing -- 2.6 Summary -- References -- Chapter 3 Alloy Design for Metal Additive Manufacturing -- 3.1 Additive Manufacturing -- 3.1.1 Metal-Based Additive Manufacturing -- 3.1.2 Alloy Development -- 3.1.3 Available Alloys -- 3.1.3.1 Ti-6Al-4V -- 3.1.3.2 Superalloys -- 3.1.3.3 316L Stainless Steel -- 3.1.3.4 AlSi10Mg -- 3.2 Melting and Cooling Processes and Associated Defects -- 3.2.1 The Process -- 3.2.2 Defects -- 3.2.2.1 Solidification Cracks -- 3.2.2.2 Liquation Cracks -- 3.2.2.3 Solid-State Cracking and Residual Stress -- 3.2.2.4 Lack-of-Fusion Porosity.

3.2.2.5 Gas Pores -- 3.2.2.6 Keyhole Porosity -- 3.2.2.7 Compositional Changes -- 3.2.2.8 Balling -- 3.2.2.9 Summary -- 3.2.3 Roles of Material Chemical-Physical Properties -- 3.2.3.1 Absorptivity/Backscattering Coefficient -- 3.2.3.2 Heat Capacity and Enthalpy of Melting -- 3.2.3.3 Thermal Conductivity -- 3.2.3.4 Surface Tension -- 3.2.3.5 Boiling Temperature and Volatility -- 3.2.3.6 Thermal Expansion and Contraction -- 3.3 Alloy Design Methodology -- 3.3.1 Keyhole Formation -- 3.3.2 Evaporation of Alloying Elements -- 3.3.3 Balling Defects -- 3.3.4 Solidification Cracking Models -- 3.3.5 Solid-State Defects -- 3.3.6 Modifications to Solidification Behavior -- 3.3.7 Examples of Alloy Design for Additive Manufacturing -- 3.3.7.1 Titanium Alloy for Medical Applications -- 3.3.7.2 Creep-Resistant Ni-Based Superalloy -- 3.3.7.3 High Strength Co-Based Superalloy for High-Temperature Applications -- 3.4 Summary -- Abbreviations -- References -- Chapter 4 Laser and Arc-Based Methods for Additive Manufacturing of Multiple Material Components -- From Design to Manufacture -- 4.1 Background -- 4.2 MMAM components design -- 4.3 Multi-material L-DED -- 4.3.1 Introduction of L-DED -- 4.3.2 Material Feeding Mechanism in Multi-Material L-DED -- 4.3.2.1 Continuous Coaxial Powder Feeding -- 4.3.2.2 Discrete Coaxial Powder Feeding -- 4.3.2.3 Simultaneous Wire and Powder Feeding -- 4.3.3 Materials and Characteristics in Multi-Material L-DED -- 4.3.3.1 L-DED of Ni-Cu Bimetal -- 4.3.3.2 L-DED of Ni-SS Bimetal -- 4.3.3.3 L-DED of Ti-Al Bimetal -- 4.3.3.4 L-DED of Ti-Ni FGM and Ti-SS FGM with Diffusion Barrier Layers -- 4.3.3.5 L-DED of Fe-Cu Bimetal -- 4.3.3.6 L-DED of Ti-ceramic Material System -- 4.4 Multi-material L-PBF -- 4.4.1 Introduction of L-PBF -- 4.4.2 Material Deposition Mechanism in Multi-Material L-PBF -- 4.4.2.1 Unidirectional Material Composition Variation.

4.4.2.2 Spatial material composition variation -- 4.4.2.3 Hybrid Methods for Discrete Powder Deposition -- 4.4.3 Materials and Characteristics in Multi-Material L-PBF -- 4.4.3.1 L-PBF of Multiple Metallic Materials -- 4.4.3.2 L-PBF of Hybrid Metal/Ceramic Materials -- 4.4.3.3 L-PBF of Hybrid Metal/Polymer Materials -- 4.4.3.4 Modeling and Simulation of Multi-Material L-PBF Processes -- 4.5 Multi-Material WAAM -- 4.5.1 Introduction of Multi-Material WAAM -- 4.5.2 Material Feeding Mechanism of Multi-Material WAAM -- 4.5.3 Materials and Characteristics in Multi-Material WAAM -- 4.5.3.1 WAAM of SS-Fe/SS Bimetals -- 4.5.3.2 WAAM of SS-Ni Bimetals -- 4.5.3.3 WAAM of Ti-Al Bimetals -- 4.5.3.4 WAAM of Fe-Al Bimetals -- 4.5.3.5 WAAM of Fe-Ni Bimetals -- 4.5.3.6 WAAM of Cu-involved Multi-Metals -- 4.6 Comparison of Multi-Material AM Technologies -- 4.7 Potential Applications of Multi-Material AM -- 4.8 Challenges of Multi-Material AM Technologies -- 4.8.1 Challenges in Multi-Material L-DED and L-PBF -- 4.8.2 Challenges in Multi-Material WAAM -- 4.9 Summary and Outlook -- 4.9.1 Summary -- 4.9.2 Outlook -- References -- Chapter 5 Modified Inherent Strain Method for Predicting Residual Deformation and Stress in Metal Additive Manufacturing -- 5.1 Background -- 5.2 Modified Inherent Strain (MIS) Method -- 5.2.1 Theory for Modification -- 5.2.2 Remarks on the IS Method -- 5.3 Extraction of ISs for L-PBF Process -- 5.4 Governing Equations for MIS-Based Sequential Analysis -- 5.5 Experimental Validation: Double Cantilever Beam -- 5.6 Simulation-Driven Design for L-PBF Process -- 5.6.1 Support Structure Selection for Crack Prevention -- 5.6.1.1 Description of the Workflow -- 5.6.1.2 Determination of the Critical J-Integral for Solid/Support Interface -- 5.6.1.3 Calculation of J-Integral at Solid/Support Interface for as-Built Part.

5.6.2 Support Structure Design Based on Topology Optimization -- 5.6.2.1 Description of the Workflow -- 5.6.2.2 Topology Optimization of the Support Structure -- 5.6.2.3 Residual Stress Estimation -- 5.6.3 Laser Scanning Path Design -- 5.6.3.1 Description of the Method -- 5.7 Summary and Outlook -- Acknowledgment -- References -- Chapter 6 High-Fidelity Modeling of Metal Additive Manufacturing -- 6.1 Background -- 6.2 Powder Spreading -- 6.2.1 Governing Equations -- 6.2.2 Model Validation -- 6.2.3 Spreading and Deposition Mechanisms -- 6.2.3.1 Rake-Type Powder Spreading -- 6.2.3.2 Roller-Type Powder Spreading -- 6.2.4 Guidance for Design and Optimization -- 6.2.5 Summary and Outlook -- 6.3 Powder Melting -- 6.3.1 Governing Equations -- 6.3.2 Heat Source Models -- 6.3.2.1 Heat Source Model of Laser Beam -- 6.3.2.2 Heat Source Model of Electron Beam -- 6.3.3 Evaporation and Recoil Pressure -- 6.3.3.1 Evaporation Model -- 6.3.3.2 Model of Flow in Common and Near-Vacuum Environments -- 6.3.4 Model Verification and Validation -- 6.3.4.1 Realistic Heat Inputs -- 6.3.4.2 Keyhole Shape and Dynamics -- 6.3.4.3 Molten Track Profile -- 6.3.5 Coupling with Powder Spreading Model -- 6.3.5.1 Single-Track Cases -- 6.3.5.2 Balling Phenomenon -- 6.3.5.3 Multi-Track Cases -- 6.3.5.4 Multilayer Cases -- 6.3.6 Porosity Reduction and Optimization -- 6.3.7 Summary and Outlook -- 6.4 Thermal Stress -- 6.4.1 Model Construction -- 6.4.2 Simulation Case -- 6.4.3 Stress Concentrations -- 6.4.4 Model Comparison and Application -- 6.4.4.1 Thermomechanical Model for Cross Comparison -- 6.4.4.2 Thermal Cracking -- 6.4.4.3 Thermal Stress-Induced Dislocation -- 6.4.5 Mitigation and Tailoring of Thermal Stress -- 6.4.6 Summary and Outlook -- 6.5 Modeling of Other Unique Phenomena -- 6.5.1 Powder Sintering in EB-PBF -- 6.5.1.1 Liquid-State Sintering -- 6.5.1.2 Phase-Field Model.