Thermomechanical model development and in situ experimental validation of the Laser Powder-Bed Fusion process

Denlinger, Erik R.; Gouge, Michael; Irwin, J. David; Michaleris, P.

doi:10.1016/j.addma.2017.05.001

Cited by 134 publications

(102 citation statements)

References 40 publications

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“…The Gaussian relation directly affects temperatures near the surface of the component, conduction through the component and to the baseplate, as well as the residual stresses that are formed within the component over time. Other heat source models can be found in the literature, such as ellipsoidal [61,62], which is used to mimic the temporal distribution into the component (as determined experimentally from a typical melt pool), which removes the requirement to model a heat source in detail, significantly reducing overall computational cost [63]. Once the energy source begins to interact with the feedstock material, the heat produced is either absorbed by the feedstock or reflected into the build chamber.…”

Section: Modeling and Simulation Of Metal-based Additive Manufacturinmentioning

confidence: 99%

“…This strategy greatly reduces the thermal gradients and subsequent thermal stresses that are incumbent during processing. Additionally, varying scan patterns has been shown to play a role in the directional dependence of final stresses in the printed component as well as the overall magnitude of the residual stress [82,85,86]. Denlinger et al (2017) proposed that reduced residual stresses were exhibited due to the rotating nature of the scanning strategy, and the homogenization of the stress field [86].…”

Section: Modeling and Simulation Of Metal-based Additive Manufacturinmentioning

confidence: 99%

“…Additionally, varying scan patterns has been shown to play a role in the directional dependence of final stresses in the printed component as well as the overall magnitude of the residual stress [82,85,86]. Denlinger et al (2017) proposed that reduced residual stresses were exhibited due to the rotating nature of the scanning strategy, and the homogenization of the stress field [86]. Similarly, Cheng et al (2016) concluded that out of various line, “island,” and “snake” SLM-processing strategies, the lowest stresses in the build direction and out-of-plane distortion occurred with a 45° alternating scanning strategy, as similar stress fields were developed in both the X and Y directions on subsequent layers [71].…”

Section: Modeling and Simulation Of Metal-based Additive Manufacturinmentioning

confidence: 99%

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Invited review article: Metal-additive manufacturing—Modeling strategies for application-optimized designs

Bandyopadhyay

Traxel

2018

Additive Manufacturing

120

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Next generation, additively-manufactured metallic parts will be designed with application-optimized geometry, composition, and functionality. Manufacturers and researchers have investigated various techniques for increasing the reliability of the metal-AM process to create these components, however, understanding and manipulating the complex phenomena that occurs within the printed component during processing remains a formidable challenge—limiting the use of these unique design capabilities. Among various approaches, thermomechanical modeling has emerged as a technique for increasing the reliability of metal-AM processes, however, most literature is specialized and challenging to interpret for users unfamiliar with numerical modeling techniques. This review article highlights fundamental modeling strategies, considerations, and results, as well as validation techniques using experimental data. A discussion of emerging research areas where simulation will enhance the metal-AM optimization process is presented, as well as a potential modeling workflow for process optimization. This review is envisioned to provide an essential framework on modeling techniques to supplement the experimental optimization process.

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Section: Modeling and Simulation Of Metal-based Additive Manufacturinmentioning

confidence: 99%

Section: Modeling and Simulation Of Metal-based Additive Manufacturinmentioning

confidence: 99%

Section: Modeling and Simulation Of Metal-based Additive Manufacturinmentioning

confidence: 99%

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Invited review article: Metal-additive manufacturing—Modeling strategies for application-optimized designs

Bandyopadhyay

Traxel

2018

Additive Manufacturing

120

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“…Remeshing is a useful tool for spatial reduction. Remeshing has been performed layer by layer [8][9][10] and locally, near the heat source [11,12]. Moreover, different techniques for merging or lumping layers and passes have been used.…”

Section: Introductionmentioning

confidence: 99%

History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing

Malmelöv

Lundbäck

Lindgren

2019

Metals

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Additive manufacturing is the process by which material is added layer by layer. In most cases, many layers are added, and the passes are lengthy relative to their thicknesses and widths. This makes finite element simulations of the process computationally demanding owing to the short time steps and large number of elements. The classical lumping approach in computational welding mechanics, popular in the 80s, is therefore, of renewed interest and is evaluated in this work. The method of lumping means that welds are merged. This allows fewer time steps and a coarser mesh. It was found that the computation time can be reduced considerably, with retained accuracy for the resulting temperatures and deformations. The residual stresses become, to a certain degree, smaller. The simulations were validated against a directed energy deposition (DED) experiment with alloy 625.a thermo-mechanical model where whole layers were added simultaneously when a part with 50 layers was built. This model was validated against an experiment. Keller et al. [17,18] described a model where several layers were added simultaneously. With their model they were able to predict deformation and residual stresses at the macroscopic level. In the current work the temperature and deformation evolution is studied when the passes are added transiently, and only lumped in the build direction. To the authors' knowledge there is no publication where the approach has been used in this way. The inherent strain method is another approach for fast prediction of the resulting deformation and residual stress in AM processes [19,20]. The method was first proposed for welding by Ueda and coworkers [21][22][23]. Li et al. [24,25] used the inherent strain approach, but instead of using strain, a residual stress tensor is added to each layer in the mechanical macro-scale model. The simulation was performed with a multi-scale model in three different scales. A micro-scale model was used to predict an equivalent heat source, which was the input to the meso-scale model. Because the AM process is very fast, it was assumed that the heat could be added to the whole layer simultaneously. In the thermo-mechanical meso-scale model, a residual stress tensor from one added layer was calculated.Finally, the mechanical model on the macro-scale was computed, wherein the material was added layer by layer and the pre-determined residual stress tensor was applied on each added layer. The drawback with the inherent strain method is that it often requires calibration. The inherent strains are in general sensitive to changes in the boundary conditions.The main aim of this work was to study the method lumping of welds, described above, and evaluate the error introduced in the modeling and the achieved reduction in computation time for the simulations. A detailed thermo-mechanical FE model was validated with in situ temperature and displacement measurements for directed energy deposition (DED) with alloy 625. All experimental data and results that are used for comparison with the sim...

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“…Additive manufacturing, also known as three-dimensional (3D) printing or direct digital manufacturing, is a class of technologies that fabricate a three-dimensional physical model directly from its digital design, by accumulating materials, usually in a layer-bylayer way. A number of additive manufacturing techniques have been developed for processing metal [1][2][3][4], polymer [5][6][7], ceramic [8], bio-materials [9], and even multiple materials [10,11], for a wide range of applications. Recently, constrained surface-based stereolithography (SL), is gaining wide attention and has been widely applied in many fields, including medical device, aerospace, education, and consumer product fields [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Air-Diffusion-Channel Constrained Surface Based Stereolithography for Three-Dimensional Printing of Objects With Wide Solid Cross Sections

Pan

Feinerman

et al. 2018

Journal of Manufacturing Science and Engineering

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Oxygen inhibition has been proved capable of reducing the separation force and enabling successful prints in constrained surface vat photopolymerization (CSVP) based three-dimensional (3D) printing processes. It has also been demonstrated as a key factor that determines the feasibility of the newly developed CSVP-based continuous 3D printing systems, such as the continuous liquid interface production. Despite its well-known importance, it is still largely unknown regarding how to control and enhance the oxygen inhibition in CSVP. To close this knowledge gap, this paper investigates the constrained surface design, which allows for continuous and sufficient air permeation to enhance the oxygen inhibition in CSVP systems. In this paper, a novel constrained surface with air-diffusion-channel is proposed. The influences of the air-diffusion-channel design parameters on the robustness of the constrained surface, the light transmission rate, and light intensity uniformity are studied. The thickness of the oxygen inhibition layer associated with the proposed constrained surface is studied analytically and experimentally. Experimental results show that the proposed air-diffusion-channel design is effective in maintaining and enhancing the oxygen-inhibition effect, and thus can increase the solid cross section size of printable parts.

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Thermomechanical model development and in situ experimental validation of the Laser Powder-Bed Fusion process

Cited by 134 publications

References 40 publications

Invited review article: Metal-additive manufacturing—Modeling strategies for application-optimized designs

Invited review article: Metal-additive manufacturing—Modeling strategies for application-optimized designs

History Reduction by Lumping for Time-Efficient Simulation of Additive Manufacturing

Air-Diffusion-Channel Constrained Surface Based Stereolithography for Three-Dimensional Printing of Objects With Wide Solid Cross Sections

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