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2.26 (a) Keyhole porosity and its formation mechanism.(b) Lack of...Figure 2.27 The combined effect of scanning velocity and beam power on the d...Figure 2.28 The relationship between melt‐pool geometry and hatching distanc...Figure 2.29 Porosity of LPBF‐made parts from AlSi10Mg as a function of hatch...Figure 2.30 Classification of powder particle properties.Figure 2.31 The relationship between particle and flow properties and flowab...Figure 2.32 Different wire‐feeding orientations.Figure 2.33 Illustration of the staircase effect.Figure 2.34 The maximum layer thickness as a measure of the overlap height o...Figure 2.35 Cross section of a part as the print layer: contour/skin and cor...Figure 2.36 (a, b) Illustration of up‐skin vs down‐skin in PBF process.(...Figure 2.37 The concept of supports structures, three different support shap...Figure 2.38 Printability of the fluids based on dimensionless Reynolds and W...Figure 2.39 The effects of (a) undersaturation and (b) oversaturation on BJ‐...Figure 2.40 H13 tool steel powder agglomeration as a result of oversaturatio...

      3 Chapter 3Figure 3.1 Laser powder bed fusion system (LPBF).Figure 3.2 Laser Powder‐Fed (LPF) system.Figure 3.3 Schematic of a binder jetting system setup.Figure 3.4 Illustration of the absorption, spontaneous emission, and stimula...Figure 3.5 Two‐level system scheme.Figure 3.6 A three‐level system scheme.Figure 3.7 Scheme of a four‐level system.Figure 3.8 The main components of a laser are shown. The active medium or ga...Figure 3.9 Solid‐state Laser scheme.Figure 3.10 Energy‐level diagram for Nd3+ doped in YAG.Figure 3.11 (a) Longitudinally excited and (b) transversely excited CO₂ lase...Figure 3.12 Laser transitions between vibrational levels in CO₂.Figure 3.13 Liquid dye laser schematic.Figure 3.14 Diode laser scheme.Figure 3.15 Scheme of a typical fiber laser.Figure 3.16 Schematic of fiber lasers that include FBGs and beam couplerFigure 3.17 Energy‐level diagram of the erbium‐doped fiber.Figure 3.18 Laser employed in laser‐based AM processes (i.e. laser powder be...Figure 3.19 Mode patterns for different TEMs.Figure 3.20 Laser beam profile.Figure 3.21 Schematic of a typical EBM apparatus.Figure 3.22 Electron beam formation schematic.Figure 3.23 Gun electrode types: (a) Tungsten (W) filament, (b) Lanthanum He...Figure 3.24 Electromagnetic Lens.Figure 3.25 Scheme of a mechanical wheel powder feeder.Figure 3.26 Schematic of gravity‐based powder feeders with a rotating wheel ...Figure 3.27 Schematic of gravity‐based powder feeders with a metering wheel....Figure 3.28 Schematic of gravity‐based powder feeders with a lobe gear.Figure 3.29 Schematic of a fluidized bed powder feeder.Figure 3.30 Schematic of a vibratory‐based powder feeder.Figure 3.31 Schematic of a typical lateral nozzle.Figure 3.32 Powder feed profile characteristics.Figure 3.33 Schematic of a typical coaxial nozzle.Figure 3.34 Powder stream at the nozzle exit to a co‐axial nozzle.Figure 3.35 Illustration of a LPBF process system setup.Figure 3.36 Schematic of a lateral wire‐feed system equipped with EBM.Figure 3.37 Schematic of a coaxial wire‐feed system.Figure 3.38 Schematic of a galvo scanner.Figure 3.39 Schematics of (a) piezo and (b) thermal inkjet print heads.Figure 3.40 Typical STL file.

      4 Chapter 4Figure 4.1 Interaction of a moving heat source and a substrate and the assoc...Figure 4.2 Schematic of phases formed in a mild steel substrate while being ...Figure 4.3 Sinusoidal electromagnetic laser beam: emitted beam, reflected be...Figure 4.4 Graphical concept of the thermal time constant.Figure 4.5 Laser pulse shaping, including pulse width W, pulse energy E, and...Figure 4.6 A typical modulated/pulsed laser beam with rising time, falling t...Figure 4.7 Dependencies of reflectivity to wavelengths, (a) from 200 to 1000...Figure 4.8 Temperature dependencies of reflectivity for Al, Cu, and steel at...Figure 4.9 Dependencies of reflectivity to the angle of incidence for s‐ray ...Figure 4.10 E‐beam interaction with a substrate and the associated signals g...Figure 4.11 Penetration depth versus absorption coefficient for accelerated ...Figure 4.12 Power density and interaction time for various heat source‐based...Figure 4.13 Schematic of physical domains of DED.Figure 4.14 Track cross section created by DED, (a) high dilution, well wett...Figure 4.15 Dynamic and equilibrium wetting angles.Figure 4.16 A schematic of the process zone during LDED powder‐fed. Melting ...Figure 4.17 Geometry and boundary conditions for a typical coaxial nozzle ex...Figure 4.18 Schematic of 3D heat flow during DED used for the development of...Figure 4.19 Balance of energy in PF‐LDED.Figure 4.20 Lumped cross section of single track deposited in LDED.Figure 4.21 Attenuated laser volume in PF‐LDED.Figure 4.22 Lumped temperature distribution at y = 0 for parameters listed i...Figure 4.23 Schematic diagram for laser powder‐fed laser‐directed deposition...Figure 4.24 Inconel 625 powder stream grayscale intensity distribution measu...Figure 4.25 Schematic diagram for melt pool geometry and deposited track [27...Figure 4.26 Schematic diagram of the solidification front in the longitudina...Figure 4.27 Laser beam intensity distribution on the substrate surface: (a) ...Figure 4.28 Melt pool temperature distribution on Inconel 625 substrate surf...Figure 4.29 Real‐time melt pool top surface peak temperature of SS 316L depo...Figure 4.30 Melt pool peak temperature map for SS 316L single‐track depositi...Figure 4.31 Real‐time local thermal profiles at different clad height locati...Figure 4.32 Effect of G and R on the mode and scale of solidification micros...Figure 4.33 Predicted in situ solidification characteristics at different me...Figure 4.34 Schematic of the laser beam, powder stream and substrate interac...Figure 4.35 Sequence of calculation in the proposed numerical model [37]....Figure 4.36 Maximum temperatures for each layer, when = 2 g/min, U = 1.5 m...Figure 4.37 Temperature distribution for the second layer deposition at t = ...Figure 4.38 Energy transformations within the deposition area of a substrate...Figure 4.39 Deposition patterns in wire‐fed EBAM.Figure 4.40 Proposed Hammerstein–Wiener nonlinear structureFigure 4.41 Experimental data: (a) multistep process speed and (b) clad/depo...Figure 4.42 Verification of Hammerstein–Wiener dynamic model using unseen da...

      5 Chapter 5Figure 5.1 Schematic of LPBF, showing physical phenomena surrounding the mel...Figure 5.2 Heat source models schematics: (a) cylindrical shape; (b) semi‐sp...Figure 5.3 Powder–laser interaction mechanisms.Figure 5.4 Thermophysical properties of bulk and powder material: (a) therma...Figure 5.5 Schematic of (a) keyhole mode and (b) conduction mode. Top figure...Figure 5.6 Temperature gradient mechanism inducing residual stress.Figure 5.7 The laser scanning path used for the case study.Figure 5.8 Geometry and mesh used in the finite element simulation of the ca...Figure 5.9 Ripples of a single track: (a) experimental results and (b) numer...Figure 5.10 Experimental surface of the multiple‐track scanning: (a) microsc...Figure 5.11 Melt pool cross section of a single track from (a) experiment (b...Figure 5.12 Multi‐track melt pool cross sections: (a) experiment and (b) sim...Figure 5.13 Schematic of the theoretical model of the LPF process.Figure 5.14 Electron acceleration between anode and cathode and electric pot...Figure 5.15 Binary head‐on collision of particles in a hexagonal grid model ...Figure 5.16 Three‐dimensional projection of a face‐centered hypercubic latti...Figure 5.17 Phases assigned to different cells in the LB method. The specifi...Figure 5.18 Exponential (60 kV) and constant (120 kV) absorption profiles....Figure 5.19 Melt pool evolution during EB‐PBF processing using the LB method...Figure 5.20 (a) Rain model schematic. (b) Generated powder bed. (c) Relative...Figure 5.21 Gaussian EB model using the constant absorption profile.Figure 5.22 (a) Micro‐scale simulation temperature distribution for a scan l...Figure 5.23 Strain evolution of a part during the build process.Figure 5.24 Comparison between the FEM model and produced parts. It uses the...

      6 Chapter 6Figure 6.1 Schematic of (a) continuous inkjet printing showing the working m...Figure 6.2 The droplet formation and flight in inkjet printing. The tail of ...Figure 6.3 (a) The thinning of the jet on the

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