scholarly journals An Overview of Additive Manufacturing Technologies—A Review to Technical Synthesis in Numerical Study of Selective Laser Melting

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3895 ◽  
Author(s):  
Abbas Razavykia ◽  
Eugenio Brusa ◽  
Cristiana Delprete ◽  
Reza Yavari
Keyword(s):  
Numerical Simulation ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Powder Bed Fusion ◽  
Laser Melting ◽  
Powder Bed ◽  
Part Quality ◽  
Melt Pool ◽  
Wide Range ◽  
Am Processes

Additive Manufacturing (AM) processes enable their deployment in broad applications from aerospace to art, design, and architecture. Part quality and performance are the main concerns during AM processes execution that the achievement of adequate characteristics can be guaranteed, considering a wide range of influencing factors, such as process parameters, material, environment, measurement, and operators training. Investigating the effects of not only the influential AM processes variables but also their interactions and coupled impacts are essential to process optimization which requires huge efforts to be made. Therefore, numerical simulation can be an effective tool that facilities the evaluation of the AM processes principles. Selective Laser Melting (SLM) is a widespread Powder Bed Fusion (PBF) AM process that due to its superior advantages, such as capability to print complex and highly customized components, which leads to an increasing attention paid by industries and academia. Temperature distribution and melt pool dynamics have paramount importance to be well simulated and correlated by part quality in terms of surface finish, induced residual stress and microstructure evolution during SLM. Summarizing numerical simulations of SLM in this survey is pointed out as one important research perspective as well as exploring the contribution of adopted approaches and practices. This review survey has been organized to give an overview of AM processes such as extrusion, photopolymerization, material jetting, laminated object manufacturing, and powder bed fusion. And in particular is targeted to discuss the conducted numerical simulation of SLM to illustrate a uniform picture of existing nonproprietary approaches to predict the heat transfer, melt pool behavior, microstructure and residual stresses analysis.

Powder-Scale Meshfree Simulations of Powder Bed Fusion Based Additive Manufacturing Processes

2019 ◽  
Author(s):  
Zongyue Fan ◽  
Hao Wang ◽  
Bo Li
Keyword(s):  
Additive Manufacturing ◽  
Optimal Transportation ◽  
The Novel ◽  
Powder Bed Fusion ◽  
Computational Framework ◽  
Powder Bed ◽  
Materials Behaviors ◽  
Melt Pool ◽  
Powder Particles ◽  
Am Processes

Abstract We present a powder-scale meshfree direct numerical simulation (DNS) capability for the powder bed fusion (PBF) based additive manufacturing (AM) processes using the novel Hot Optimal Transportation Meshfree (HOTM) method. The HOTM method is an incremental Lagrangian meshfree computational framework for materials behaviors under extreme thermomechanical loading conditions, which combines the Optimal Transportation Meshfree (OTM) method and the variational thermomechanical constitutive updates. The realistic multi-layer powder bed geometry is modeled explicitly in the HOTM simulations based on experimental data. A phase-aware constitutive model is developed to predict the phase change and multiphase mixing during the PBF AM processes automatically. The governing equations including the linear momentum and energy conservation equations are solved for the multiphase flow simultaneously to predict the deformation, temperature and local state of the powder particles. The powder-scale DNS is employed to study the influence of various laser powers on the melt pool thermodynamics.

Quasicrystalline Composites by Additive Manufacturing

2019 ◽  
Vol 818 ◽  
pp. 72-76 ◽  
Author(s):  
Konda Gokuldoss Prashanth ◽  
Sergio Scudino
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Complex Shape ◽  
Powder Bed Fusion ◽  
Laser Melting ◽  
Powder Bed ◽  
Novel Materials ◽  
Tunable Properties

Laser based powder bed fusion (LBPF) or selective laser melting (SLM) is making a leap march towards fabricating novel materials with improved functionalities. An attempt has been made here to fabricate hard quasicrystalline composites via SLM, which demonstrates that the process parameters can be used to vary the phases in the composites. The mechanical properties of the composite depend on their constituents and hence can be varied by varying the process parameters. The results show that SLM not only produces parts with improved functionalities and complex shape but also leads to defined phases and tunable properties.

scholarly journals Feedback Control of Melt Pool Area in Selective Laser Melting Additive Manufacturing Process

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1547
Author(s):  
Syed Zahid Hussain ◽  
Zareena Kausar ◽  
Zafar Ullah Koreshi ◽  
Shakil R. Sheikh ◽  
Hafiz Zia Ur Rehman ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Feedback Control ◽  
Selective Laser Melting ◽  
Manufacturing Process ◽  
Thermal Model ◽  
Laser Melting ◽  
Powder Bed ◽  
Melt Pool ◽  
Melt Pool Size ◽  
Pool Area

Selective laser melting (SLM), a metal powder fusion additive manufacturing process, has the potential to manufacture complex components for aerospace and biomedical implants. Large-scale adaptation of these technologies is hampered due to the presence of defects such as porosity and part distortion. Nonuniform melt pool size is a major cause of these defects. The melt pool size changes due to heat from the previous powder bed tracks. In this work, the effect of heat sourced from neighbouring tracks was modelled and feedback control was designed. The objective of control is to regulate the melt pool cross-sectional area rejecting the effect of heat from neighbouring tracks within a layer of the powder bed. The SLM process’s thermal model was developed using the energy balance of lumped melt pool volume. The disturbing heat from neighbouring tracks was modelled as the initial temperature of the melt pool. Combining the thermal model with disturbance model resulted in a nonlinear model describing melt pool evolution. The PID, a classical feedback control approach, was used to minimize the effect of intertrack disturbance on the melt pool area. The controller was tuned for the desired melt pool area in a known environment. Simulation results revealed that the proposed controller regulated the desired melt pool area during the scan of multiple tracks of a powder layer within 16 milliseconds and within a length of 0.04 mm reducing laser power by 10% approximately in five tracks. This reduced the chance of pore formation. Hence, it enhances the quality of components manufactured using the SLM process, reducing defects.

Closed-Loop Simulation Integrating Finite Element Modeling With Feedback Controls in Powder Bed Fusion Additive Manufacturing

2020 ◽  
Author(s):  
Dan Wang ◽  
Xu Chen
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Finite Element Modeling ◽  
Closed Loop ◽  
Agile Manufacturing ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Element Modeling ◽  
Melt Pool ◽  
Wide Range

Abstract Powder bed fusion (PBF) additive manufacturing has enabled unmatched agile manufacturing of a wide range of products from engine components to medical implants. While high-fidelity finite element modeling and feedback control have been identified key for predicting and engineering part qualities in PBF, existing results in each realm are developed in opposite computational architectures wildly different in time scale. Integrating both realms, this paper builds a first-instance closed-loop simulation framework by utilizing the output signals retrieved from the finite element model (FEM) to directly update the control signals sent to the model. The proposed closed-loop simulation enables testing the limits of advanced controls in PBF and surveying the parameter space fully to generate more predictable part qualities. Along the course of formulating the framework, we verify the FEM by comparing its results with experimental and analytical solutions and then use the FEM to understand the melt-pool evolution induced by the in-layer thermomechanical interactions. From there, we build a repetitive control algorithm to greatly attenuate variations of the melt pool width.

scholarly journals A novel physics-based and data-supported microstructure model for part-scale simulation of laser powder bed fusion of Ti-6Al-4V

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jonas Nitzler ◽  
Christoph Meier ◽  
Kei W. Müller ◽  
Wolfgang A. Wall ◽  
N. E. Hodge
Keyword(s):  
Selective Laser Melting ◽  
Microstructure Evolution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Laser Melting ◽  
Cooling Rates ◽  
Powder Bed ◽  
Proposed Model ◽  
Microstructure Model ◽  
Transformation Diagrams

AbstractThe elasto-plastic material behavior, material strength and failure modes of metals fabricated by additive manufacturing technologies are significantly determined by the underlying process-specific microstructure evolution. In this work a novel physics-based and data-supported phenomenological microstructure model for Ti-6Al-4V is proposed that is suitable for the part-scale simulation of laser powder bed fusion processes. The model predicts spatially homogenized phase fractions of the most relevant microstructural species, namely the stable $$\beta $$ β -phase, the stable $$\alpha _{\text {s}}$$ α s -phase as well as the metastable Martensite $$\alpha _{\text {m}}$$ α m -phase, in a physically consistent manner. In particular, the modeled microstructure evolution, in form of diffusion-based and non-diffusional transformations, is a pure consequence of energy and mobility competitions among the different species, without the need for heuristic transformation criteria as often applied in existing models. The mathematically consistent formulation of the evolution equations in rate form renders the model suitable for the practically relevant scenario of temperature- or time-dependent diffusion coefficients, arbitrary temperature profiles, and multiple coexisting phases. Due to its physically motivated foundation, the proposed model requires only a minimal number of free parameters, which are determined in an inverse identification process considering a broad experimental data basis in form of time-temperature transformation diagrams. Subsequently, the predictive ability of the model is demonstrated by means of continuous cooling transformation diagrams, showing that experimentally observed characteristics such as critical cooling rates emerge naturally from the proposed microstructure model, instead of being enforced as heuristic transformation criteria. Eventually, the proposed model is exploited to predict the microstructure evolution for a realistic selective laser melting application scenario and for the cooling/quenching process of a Ti-6Al-4V cube of practically relevant size. Numerical results confirm experimental observations that Martensite is the dominating microstructure species in regimes of high cooling rates, e.g., due to highly localized heat sources or in near-surface domains, while a proper manipulation of the temperature field, e.g., by preheating the base-plate in selective laser melting, can suppress the formation of this metastable phase.

Toward Metamodels for Composable and Reusable Additive Manufacturing Process Models

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Paul Witherell ◽  
Shaw Feng ◽  
Timothy W. Simpson ◽  
David B. Saint John ◽  
Pan Michaleris ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Metal Powder ◽  
Manufacturing Process ◽  
Process Model ◽  
Model Development ◽  
Process Models ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Future Work ◽  
Am Processes

In this paper, we advocate for a more harmonized approach to model development for additive manufacturing (AM) processes, through classification and metamodeling that will support AM process model composability, reusability, and integration. We review several types of AM process models and use the direct metal powder bed fusion AM process to provide illustrative examples of the proposed classification and metamodel approach. We describe how a coordinated approach can be used to extend modeling capabilities by promoting model composability. As part of future work, a framework is envisioned to realize a more coherent strategy for model development and deployment.

scholarly journals Additive Manufacturing of Bulk Nanocrystalline FeNdB Based Permanent Magnets

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 538
Author(s):  
Dagmar Goll ◽  
Felix Trauter ◽  
Timo Bernthaler ◽  
Jochen Schanz ◽  
Harald Riegel ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Melt Spinning ◽  
Permanent Magnets ◽  
Maximum Energy ◽  
Laser Melting ◽  
Powder Bed ◽  
Melt Pool ◽  
Bulk Nanocrystalline ◽  
Ribbon Structures ◽  
Nanocrystalline Ribbon

Lab scale additive manufacturing of Fe-Nd-B based powders was performed to realize bulk nanocrystalline Fe-Nd-B based permanent magnets. For fabrication a special inert gas process chamber for laser powder bed fusion was used. Inspired by the nanocrystalline ribbon structures, well-known from melt-spinning, the concept was successfully transferred to the additive manufactured parts. For example, for Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8 (excess rare earth (RE) = Nd, Pr; the amount of additives was chosen following Magnequench (MQ) powder composition) a maximum coercivity of µ0Hc = 1.16 T, remanence Jr = 0.58 T and maximum energy density of (BH)max = 62.3 kJ/m3 have been achieved. The most important prerequisite to develop nanocrystalline printed parts with good magnetic properties is to enable rapid solidification during selective laser melting. This is made possible by a shallow melt pool during laser melting. Melt pool depths as low as 20 to 40 µm have been achieved. The printed bulk nanocrystalline Fe-Nd-B based permanent magnets have the potential to realize magnets known so far as polymer bonded magnets without polymer.

New Hammerstein Modeling and Analysis for Controlling Melt Pool Width in Powder Bed Fusion Additive Manufacturing

2021 ◽  
pp. 1-7
Author(s):  
Dan Wang ◽  
Xinyu Zhao ◽  
Xu Chen
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Process Variations ◽  
Element Model ◽  
Hammerstein Model ◽  
Powder Bed Fusion ◽  
Modeling And Analysis ◽  
Powder Bed ◽  
Melt Pool ◽  
Linearized Model

Abstract Despite the advantages and emerging applications, broader adoption of powder bed fusion (PBF) additive manufacturing is challenged by insufficient reliability and in-process variations. Finite element modeling and control-oriented modeling have been identified fundamental for predicting and engineering part qualities in PBF. This paper first builds a finite element model (FEM) of the thermal fields to look into the convoluted thermal interactions during the PBF process. Using the FEM data, we identify a novel surrogate system model from the laser power to the melt pool width. Linking a linearized model with a memoryless nonlinear submodel, we develop a physics-based Hammerstein model that captures the complex spatiotemporal thermomechanical dynamics. We verify the accuracy of the Hammerstein model using the FEM and prove that the linearized model is only a representation of the Hammerstein model around the equilibrium point. Along the way, we conduct the stability and robustness analyses and formalize the Hammerstein model to facilitate the subsequent control designs.

A Comparative Study Between Selective Laser Melting and Electron Beam Additive Manufacturing Based on Thermal Modeling

2018 ◽  
Author(s):  
M. Shafiqur Rahman ◽  
Paul J. Schilling ◽  
Paul D. Herrington ◽  
Uttam K. Chakravarty
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Heat Source ◽  
Selective Laser Melting ◽  
Thermal Modeling ◽  
Maximum Temperature ◽  
Full Density ◽  
Rate Variation ◽  
Laser Melting ◽  
Melt Pool

Selective Laser Melting (SLM) and Electron Beam Additive Manufacturing (EBAM) are two of the most promising additive manufacturing technologies that can make full density metallic components using layer-by-layer fabrication methods. In this study, three-dimensional computational fluid dynamics models with Ti-6Al-4V powder were developed to conduct numerical simulations of both the SLM and EBAM processes. A moving conical volumetric heat source with Gaussian distribution and temperature-dependent thermal properties were incorporated in the thermal modeling of both processes. The melt-pool geometry and its thermal behavior were investigated numerically and results for temperature profile, cooling rate, variation in specific heat, density, thermal conductivity, and enthalpy were obtained with similar heat source specifications. Results obtained from the two models at the same maximum temperature of the melt pool were then compared to describe their deterministic features to be considered for industrial applications. Validation of the modeling was performed by comparing the EBAM simulation results with the EBAM experimental results for melt pool geometry.

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