Bayesian Calibration of Multiple Coupled Simulation Models for Metal Additive Manufacturing: A Bayesian Network Approach

2021 ◽  
Author(s):  
Jiahui Ye ◽  
Mohamad Mahmoudi ◽  
Kubra Karayagiz ◽  
Luke Johnson ◽  
Raiyan Seede ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Bayesian Network ◽  
Simulation Models ◽  
Processing Parameters ◽  
Network Approach ◽  
Structure Property ◽  
Coupled Simulation ◽  
Niobium Alloys ◽  
Powder Bed ◽  
Physical Phenomena

Abstract Modeling and simulation for additive manufacturing (AM) are critical enablers for understanding process physics, conducting process planning and optimization, and streamlining qualification and certification. It is often the case that a suite of hierarchically linked (or coupled) simulation models is needed to achieve the above task, as the entirety of the complex physical phenomena relevant to the understanding of process-structure-property-performance relationships in the context of AM precludes the use of a single simulation framework. In this study using a Bayesian network approach, we address the important problem of conducting uncertainty quantification (UQ) analysis for multiple hierarchical models to establish process-microstructure relationships in laser powder bed fusion (LPBF) AM. More significantly, we present the framework to calibrate and analyze simulation models that have unmeasurable variables, which are quantities of interest predicted by an upstream model and necessary for the downstream model in the chain that are difficult or impossible to observe experimentally. We validate the framework using a case study on predicting the microstructure of binary nickel-niobium alloys processed using LPBF as a function of processing parameters. Our framework is shown to be able to predict segregation of niobium with up to 94.3% prediction accuracy in test data.

Additive Manufacturing of Glass

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Junjie Luo ◽  
Heng Pan ◽  
Edward C. Kinzel
Keyword(s):  
Additive Manufacturing ◽  
Glass Powder ◽  
Processing Parameters ◽  
Gradient Index ◽  
Continuous Line ◽  
Single Track ◽  
Laser Melting ◽  
Powder Bed ◽  
Transparent Parts ◽  
Insight Into

Selective laser melting (SLM) is a technique for the additive manufacturing (AM) of metals, plastics, and even ceramics. This paper explores using SLM for depositing glass structures. A CO2 laser is used to locally melt portions of a powder bed to study the effects of process parameters on stationary particle formation as well as continuous line quality. Numerical modeling is also applied to gain insight into the physical process. The experimental and numerical results indicate that the absorptivity of the glass powder is nearly constant with respect to the processing parameters. These results are used to deposit layered single-track wide walls to demonstrate the potential of using the SLM process for building transparent parts. Finally, the powder bed process is compared to a wire-fed approach. AM of glass is relevant for gradient index optics, systems with embedded optics, and the formation of hermetic seals.

scholarly journals Detection of Typical Metal Additive Manufacturing Defects by the Application of Thermographic Techniques

Proceedings ◽  
2019 ◽  
Vol 27 (1) ◽  
pp. 24
Author(s):  
D’Accardi ◽  
Altenburg ◽  
Maierhofer ◽  
Palumbo ◽  
Galietti
Keyword(s):  
Additive Manufacturing ◽  
Processing Parameters ◽  
Layer By Layer ◽  
Metal Powders ◽  
Destructive Testing ◽  
Powder Bed ◽  
Manufacturing Defects ◽  
Metal Additive Manufacturing ◽  
Time Required ◽  
Metal Additive

One of the most advanced technologies of Metal Additive Manufacturing (AM) is the Laser Powder Bed Fusion process (L-PBF), also known as Selective Laser Melting (SLM). This process involves the deposition and fusion, layer by layer, of very fine metal powders and structure and quality of the final component strongly depends on several processing parameters, for example the laser parameters. Due to the complexity of the process it is necessary to assure the absence of defects in the final component, in order to accept or discard it. Thermography is a very fast non-destructive testing (NDT) technique. Its applicability for defect detection in AM produced parts would significantly reduce costs and time required for NDT, making it versatile and very competitive.

Influence of multiple scan fields on the processing of 316L stainless steel using laser powder bed fusion

2020 ◽  
pp. 146442072094854
Author(s):  
TC Leça ◽  
TEF Silva ◽  
AMP de Jesus ◽  
Rui L Neto ◽  
Jorge L Alves ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Metal Cutting ◽  
High Volume ◽  
Processing Parameters ◽  
Powder Bed ◽  
Multiple Scan ◽  
Laser Systems ◽  
Sharp Growth ◽  
Single Field

The sharp growth that additive manufacturing has been showing recently has broadened its application field and resulted in more varied demand of high-volume parts as well as a general increase in part series. The current focus on productivity enhancement of additive manufacturing has imposed the implementation of multiple-laser systems with larger scan fields. Its usage, combined with adequate layer thickness and laser power selection, makes high-volume parts less challenging to obtain. This paper focuses on understanding the influence of using multiple-scan fields for the fabrication of large components, especially on the parts region corresponding to scan field interface. The microstructure as well as mechanical behaviour of the multi-field manufactured samples are compared with parts fabricated using a single-field, for distinct processing parameters. Moreover, given the unreliability of additive manufacturing regarding dimensional and geometrical tolerances with increasing build rates, post-processing metal-cutting operations were studied towards additive manufacturing process hybridization. Despite the typical additive manufacturing process variability, a set of parameters, within testing conditions, could be identified as the most appropriate solution towards mechanical strength enhancement. Nonetheless, porosity levels can significantly impact the ductility of parts, which may be additionally compromised by its occurrence in the scan-field interface region.

scholarly journals Discrete Element Method Analysis of the Spreading Mechanism and Its Influence on Powder Bed Characteristics in Additive Manufacturing

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 392
Author(s):  
Valerio Lampitella ◽  
Marco Trofa ◽  
Antonello Astarita ◽  
Gaetano D’Avino
Keyword(s):  
Additive Manufacturing ◽  
Discrete Element Method ◽  
Ad Hoc ◽  
Low Cost ◽  
Discrete Element ◽  
Spreading Process ◽  
Powder Bed ◽  
Physical Phenomena ◽  
Element Method

Laser powder bed fusion additive manufacturing is among the most used industrial processes, allowing for the production of customizable and geometrically complex parts at relatively low cost. Although different aspects of the powder spreading process have been investigated, questions remain on the process repeatability on the actual beam–powder bed interaction. Given the influence of the formed bed on the quality of the final part, understanding the spreading mechanism is crucial for process optimization. In this work, a Discrete Element Method (DEM) model of the spreading process is adopted to investigate the spreading process and underline the physical phenomena occurring. With parameters validated through ad hoc experiments, two spreading velocities, accounting for two different flow regimes, are simulated. The powder distribution in both the accumulation and deposition zone is investigated. Attention is placed on how density, effective layer thickness, and particle size distribution vary throughout the powder bed. The physical mechanism leading to the observed characteristics is discussed, effectively defining the window for the process parameters.

scholarly journals Investigation of laser-powder interaction in laser powder bed fusion process in additive manufacturing

2021 ◽  
Vol 249 ◽  
pp. 12002
Author(s):  
Erlei Li ◽  
Lin Wang ◽  
Ruiping Zou ◽  
Aibing Yu ◽  
Zongyan Zhou
Keyword(s):  
Additive Manufacturing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Melt Pool ◽  
Computational Fluid Dynamics Cfd ◽  
Laser Rays ◽  
Physical Phenomena ◽  
Melting And Solidification ◽  
Packed Powder

Laser powder bed fusion (LPBF) is one of the most promising additive manufacturing (AM) technologies to fabricate metal components using laser beams. To understand the underlying thermal and physical phenomena in LPBF process, discrete element method (DEM) is applied to generate the randomly packed powder, then computational fluid dynamics (CFD) coupled with volume of fluid (VOF) is adopted to simulate the laser-powder interaction. The penetration and multiple reflection of laser rays is traced. The physics of melting and solidification is captured. The temperature profile indicates the laser travel path and the adsorption and transmission of laser rays with the powder. The wetting behaviour of the melt pool driven by the capillary forces leads to the formation of pores at the connection zone. It has been demonstrated that the developed model can capture the laser-powder interaction for further understanding of LPBF process.

Additive Manufacturing of Glass

2014 ◽  
Author(s):  
Junjie Luo ◽  
Heng Pan ◽  
Edward C. Kinzel
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Glass Powder ◽  
Processing Parameters ◽  
Gradient Index ◽  
Continuous Line ◽  
Laser Melting ◽  
Powder Bed ◽  
Hermetic Seal ◽  
Insight Into

Additive manufacturing has shown potential for manufacturing parts out of metals, plastics and even ceramics. This paper reports on Selective Laser Melting (SLM) for depositing glass which has significantly different material properties from metals, ceramics or polymers. A CO2 laser is used to locally melt portions of a powder bed to explore the effects of process parameters on stationary particle formation as well as continuous line quality. Numerical modeling is also applied to gain insight into the physical process. The experimental and numerical results indicate that the absorptivity of the glass powder is nearly constant with respect to the processing parameters. Finally we show that higher quality parts can be created using a wire-fed instead of powder-bed process. Industrially, the additive manufacturing of glass is potentially relevant for gradient index optics, systems with embedded optics and applications where glass is used to form a hermetic seal.

scholarly journals Development of a Laser Powder Bed Fusion Process Tailored for the Additive Manufacturing of High-Quality Components Made of the Commercial Magnesium Alloy WE43

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 887
Author(s):  
Stefan Julmi ◽  
Arvid Abel ◽  
Niklas Gerdes ◽  
Christian Hoff ◽  
Jörg Hermsdorf ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Casting Process ◽  
Processing Parameters ◽  
Second Step ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Test Pieces ◽  
Alloy We43 ◽  
Cast Parts

Additive manufacturing (AM) has become increasingly important over the last decade and the quality of the products generated with AM technology has strongly improved. The most common metals that are processed by AM techniques are steel, titanium (Ti) or aluminum (Al) alloys. However, the proportion of magnesium (Mg) in AM is still negligible, possibly due to the poor processability of Mg in comparison to other metals. Mg parts are usually produced by various casting processes and the experiences in additive manufacturing of Mg are still limited. To address this issue, a parameter screening was conducted in the present study with experiments designed to find the most influential process parameters. In a second step, these parameters were optimized in order to fabricate parts with the highest relative density. This experiment led to processing parameters with which specimens with relative densities above 99.9% could be created. These high-density specimens were then utilized in the fabrication of test pieces with several different geometries, in order to compare the material properties resulting from both the casting process and the powder bed fusion (PBF-LB) process. In this comparison, the compositions of the occurring phases and the alloys’ microstructures as well as the mechanical properties were investigated. Typically, the microstructure of metal parts, produced by PBF-LB, consisted of much finer grains compared to as-cast parts. Consequently, the strength of Mg parts generated by PBF-LB could be further increased.

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