Multiscale Modeling of the Laser Additive Manufacturing Process

2020 ◽  
pp. 235-248
Author(s):  
Seshadev Sahoo ◽  
Jyotirmoy Nandy
Keyword(s):  
Additive Manufacturing ◽  
Multiscale Modeling ◽  
Manufacturing Sector ◽  
Layer By Layer ◽  
Waste Production ◽  
Detailed Classification ◽  
Wide Range ◽  
Manufacturing Techniques ◽  
The Many ◽  
Efficient Manufacturing

Additive manufacturing (AM) has emerged as the most versatile process in the manufacturing sector. The advantages of AM such as applicability in a wide range of industries, ease of manufacturing, and reduction in waste production have increased its demand over the past decades. Out of the many techniques under AM, direct metal laser sintering (DMLS) is one of the most efficient manufacturing techniques that uses a high-powered laser beam to sinter metal powders in a layer-by-layer fashion. With the current usage of computational modeling, the prediction of microstructure evolution and other thermo-mechanical properties of different materials have been of great advantage to researchers. Along with a detailed classification of AM techniques, this chapter focuses on the use of continuum, phase field, and atomistic modeling under the DMLS process. The results show that multiscale modeling can be advantageous in gaining deeper insight into various phenomena like diffusion and sintering.

scholarly journals Taking into account thermal residual stresses in topology optimization of structures built by additive manufacturing

2018 ◽  
Vol 28 (12) ◽  
pp. 2313-2366 ◽  
Author(s):  
Grégoire Allaire ◽  
Lukas Jakabčin
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
Residual Stresses ◽  
Heat Fluxes ◽  
Powder Layer ◽  
Layer By Layer ◽  
Thermal Deformations ◽  
Thermal Residual Stresses ◽  
Structural Design Optimization ◽  
Manufacturing Techniques

We introduce a model and several constraints for shape and topology optimization of structures, built by additive manufacturing techniques. The goal of these constraints is to take into account the thermal residual stresses or the thermal deformations, generated by processes like Selective Laser Melting, right from the beginning of the structural design optimization. In other words, the structure is optimized concurrently for its final use and for its behavior during the layer-by-layer production process. It is well known that metallic additive manufacturing generates very high temperatures and heat fluxes, which in turn yield thermal deformations that may prevent the coating of a new powder layer, or thermal residual stresses that may hinder the mechanical properties of the final design. Our proposed constraints are targeted to avoid these undesired effects. Shape derivatives are computed by an adjoint method and are incorporated into a level set numerical optimization algorithm. Several 2D and 3D numerical examples demonstrate the interest and effectiveness of our approach.

Between the Nile and the Ocean. The bead assemblage from the Eastern Desert (4th–6th centuries AD)

2018 ◽  
Vol 26 (1) ◽  
pp. 719-747 ◽  
Author(s):  
Joanna Then-Obłuska
Keyword(s):  
Red Sea ◽  
Eastern Desert ◽  
Sri Lankan ◽  
Nile Valley ◽  
Long Distance ◽  
South Indian ◽  
Wide Range ◽  
Settlement Site ◽  
Manufacturing Techniques ◽  
The Many

More than 200 beads and pendants were found in seven trash middens excavated at the 4th/5th to the 6th century AD settlement site in Shenshef in the Eastern Desert of Egypt. The site lies close to the Sudanese border and the Red Sea coast, and about 20 km to the southwest of the ancient port of Berenike. Although the purpose of the settlement has not been established, excavations provided a wide range of imports from the Mediterranean region and the Indian Ocean. An overview of the materials and manufacturing techniques applied in the production of the beads and pendants confirms the short- and long-distance contacts of Shenshef inhabitants. In addition to the many bead parallels that link the site with the Red Sea ports and the Nile Valley region up to the First Cataract, the presence of South Indian/Sri Lankan beads at Shenshef is especially meaningful. They may be proof of the intermediary role played by the Shenshef inhabitants in trading overseas imports into the Nubian Nile Valley region.

Build Direction for Improved Process Plan in Multi-Material Additive Manufacturing

2014 ◽  
Author(s):  
Bashir Khoda
Keyword(s):  
Additive Manufacturing ◽  
Material Object ◽  
Layer By Layer ◽  
Multiple Features ◽  
Process Plan ◽  
Material Deposition ◽  
Heterogeneous Object ◽  
Build Time ◽  
Material Process ◽  
Manufacturing Techniques

Current additive manufacturing processes mostly accustomed with mono-material process plan algorithm to build object layer by layer. However, building a multi-material or heterogeneous object with an additive manufacturing system is fairly new but emerging concept. Unlike mono-material object, heterogeneous object contains multiple features or inhomogeneous architecture and can be decomposed into two dimensional heterogeneous layers with islands where each island represents associated feature’s properties. The material deposition path-plan in such multi-feature/multi-contour layers requires more resources and may affect the part integrity, quality, and build time. A novel framework is presented in this paper to determine the optimum build direction for heterogeneous object by differentiating the slice based on the resources requirement. Slices are bundled based on the heterogeneity and the effect of build directions are quantified considering the feature characteristics and manufacturing attributes. The proposed methodology is illustrated by examples with 50% or more homogeneous slices along the optimum build direction. The outcome would certainly benefit the process plan for multi-material additive manufacturing techniques.

scholarly journals A review on integration of lightweight gradient lattice structures in additive manufacturing parts

2020 ◽  
Vol 12 (6) ◽  
pp. 168781402091695
Author(s):  
Asliah Seharing ◽  
Abdul Hadi Azman ◽  
Shahrum Abdullah
Keyword(s):  
Additive Manufacturing ◽  
Weight Ratio ◽  
Design Parameters ◽  
Layer By Layer ◽  
Lattice Structures ◽  
Unit Cells ◽  
Metallic Additive ◽  
Manufacturing Techniques ◽  
Future Work ◽  
Design Freedom

This review analyses the design, mechanical behaviors, manufacturability, and application of gradient lattice structures manufactured via metallic additive manufacturing technology. By varying the design parameters such as cell size, strut length, and strut diameter of the unit cells in lattice structures, a gradient property is obtained to achieve different levels of functionalities and optimize strength-to-weight ratio characteristics. Gradient lattice structures offer variable densification and porosities; and can combine more than one type of unit cells with different topologies which results in different performances in mechanical behavior layer-by-layer compared to non-gradient lattice structures. Additive manufacturing techniques are capable of manufacturing complex lightweight parts such as uniform and gradient lattice structures and hence offer design freedom for engineers. Despite these advantages, additive manufacturing has its own unique drawbacks in manufacturing lattice structures. The rules and strategies in overcoming the constraints are discussed and recommendations for future work were proposed.

scholarly journals Fatigue Cracking of Additively Manufactured Materials—Process and Material Perspectives

2020 ◽  
Vol 10 (16) ◽  
pp. 5556
Author(s):  
Torsten Fischer ◽  
Bernd Kuhn ◽  
Detlef Rieck ◽  
Axel Schulz ◽  
Ralf Trieglaff ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Fatigue Strength ◽  
Process Control ◽  
High Performance ◽  
Chemical Engineering ◽  
Fatigue Cracking ◽  
Metal Powders ◽  
Wide Range ◽  
Manufacturing Techniques ◽  
The Impact

Strong efforts are made internationally to optimize the process control of laser additive manufacturing processes. For this purpose, advanced detectors and monitoring software are being developed to control the quality of production. However, commercial suppliers of metal powders and part manufacturers are essentially focused on well-established materials. This article demonstrates the potential of optimized process control. Furthermore, we outline the development of a new high temperature structural steel, tailored to best utilize the advantages of additive manufacturing techniques. In this context, the impact of production-induced porosity on fatigue strength of austenitic 316L is presented. Additionally, we discuss the first conceptual results of a novel ferritic steel, named HiperFer (High Performance Ferrite), which was designed for increased fatigue strength. This ferritic, Laves phase-strengthened, stainless steel could be used for a wide range of structural components in power and (petro)chemical engineering at maximum temperatures ranging from about 580 to 650 °C. This material benefits from in situ heat treatment and counteracts process-related defects by “reactive” crack obstruction mechanisms, hampering both crack initiation and crack propagation. In this way, increased fatigue resistance and safety can be achieved.

scholarly journals Theoretical and Experimental Investigation on the 3D Surface Roughness of Material Extrusion Additive Manufacturing Products

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 293
Author(s):  
Shijie Jiang ◽  
Ke Hu ◽  
Yang Zhan ◽  
Chunyu Zhao ◽  
Xiaopeng Li
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Surface Defects ◽  
Raw Materials ◽  
Fiber Direction ◽  
Layer By Layer ◽  
Forming Process ◽  
Material Extrusion ◽  
Proposed Model ◽  
Wide Range

Material extrusion (ME), one of the most widely used additive manufacturing technique, has the advantages of freedom of design, wide range of raw materials, strong ability to manufacture complex products, etc. However, ME products have obvious surface defects due to the layer-by-layer manufacturing characteristics. To reveal the generation mechanism, the three-dimensional surface roughness (3DSR) of ME products was investigated theoretically and experimentally. Based on the forming process of bonding neck, the 3DSR theoretical model in two different directions (vertical and parallel to the fiber direction) was established respectively. The preparation of ME samples was then completed and a series of experimental tests were performed to determine their surface roughness with the laser microscope. Through the comparison between theoretical and experimental results, the proposed model was validated. In addition, sensitivity analysis is implemented onto the proposed model, investigating how layer thickness, extrusion temperature, and extrusion width influence the samples’ surface roughness. This study provides theoretical basis and technical insight into improving the surface quality of ME products.

scholarly journals WAAM Application for EPC Company

2019 ◽  
Vol 269 ◽  
pp. 05002
Author(s):  
Priyantomo Agustinus Ananda
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Process ◽  
Complex Geometry ◽  
Welding Process ◽  
Feed Speed ◽  
Layer By Layer ◽  
Delivery Time ◽  
Project Schedule ◽  
Wide Range ◽  
Wire Arc Additive Manufacturing

WAAM ( Wire + Arc Additive Manufacturing) is a process of adding material layer by layer in order to build a near net shape components. It shows a further promising future for fabricating large expensive metal components with complex geometry. Engineering Procurement and Construction (EPC) company as one of the industrial section which related with engineering design and products, wide range of material type, and shop based or site based manufacturing process have been dealing with conventional manufacturing and procurement process in order to fulfill its requirement for custom parts and items for the project completion purpose. During the conventional process, there is a risk during the transportation of the products from the manufacturing shop to then site project, this risk is even greater when the delivery time take part as one of the essential part which affect the project schedule. Wire Arc Additive Manufacturing process offering an alternative process to shorten the delivery time and process for a selected material and engineered items, with the consideration of essential variables which can affect the final products of WAAM process, such as : heat input, wire feed speed, travel speed, shielding gas, welding process and robotic system applied. In this paper, the possibilities of WAAM application in EPC company will be assessed, an in depth literature review of the various process which possible to applied, include the loss and benefit compared with conventional method will be presented. The main objective is to identify the current challenge and the prospect of WAAM application in EPC company.

From Conventional to Additive Manufacturing: Determining Component Fabrication Feasibility

2018 ◽  
Author(s):  
Seyedeh Elaheh Ghiasian ◽  
Prakhar Jaiswal ◽  
Rahul Rai ◽  
Kemper Lewis
Keyword(s):  
Additive Manufacturing ◽  
Economic Feasibility ◽  
The Core ◽  
Industrial Grade ◽  
Wide Range ◽  
Subtractive Manufacturing ◽  
Continuous Objects ◽  
Manufacturing Techniques ◽  
Primary Assessment ◽  
Core Functionality

The use of additive manufacturing (AM) for fabricating industrial grade components has increased significantly in recent years. Numerous industrial entities are looking to leverage new AM techniques to enable fabrication of components that were typically manufactured previously using conventional manufacturing techniques such as subtractive manufacturing or casting. Therefore, it is becoming increasingly important to be able to rigorously evaluate the technical and economic feasibility of additively manufacturing a component relative to conventional alternatives. In order to support this evaluation, this paper presents a framework that investigates fabrication feasibility for AM from three perspectives: geometric evaluation, build orientation/support generation, and resources necessary (i.e., cost and time). The core functionality of the framework is enabled on voxelized model representation, discrete and binary formats of 3D continuous objects. AM fabrication feasibility analysis is applied to 34 various parts representing a wide range of manifolds and valves manufactured using conventional manufacturing techniques, components commonly found in the aerospace industry. Results obtained illustrate the capability and generalizability of the framework to analyze intricate geometries and provide a primary assessment for the feasibility of the AM process.

scholarly journals Additive manufacturing of steels: a review of achievements and challenges

2020 ◽  
Vol 56 (1) ◽  
pp. 64-107 ◽  
Author(s):  
Nima Haghdadi ◽  
Majid Laleh ◽  
Maxwell Moyle ◽  
Sophie Primig
Keyword(s):  
Additive Manufacturing ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Layer By Layer ◽  
Powder Bed ◽  
Heating Source ◽  
Wide Range ◽  
Complex Engineering ◽  
Precipitation Phenomena ◽  
Directed Energy

Abstract Metal additive manufacturing (AM), also known as 3D printing, is a disruptive manufacturing technology in which complex engineering parts are produced in a layer-by-layer manner, using a high-energy heating source and powder, wire or sheet as feeding material. The current paper aims to review the achievements in AM of steels in its ability to obtain superior properties that cannot be achieved through conventional manufacturing routes, thanks to the unique microstructural evolution in AM. The challenges that AM encounters are also reviewed, and suggestions for overcoming these challenges are provided if applicable. We focus on laser powder bed fusion and directed energy deposition as these two methods are currently the most common AM methods to process steels. The main foci are on austenitic stainless steels and maraging/precipitation-hardened (PH) steels, the two so far most widely used classes of steels in AM, before summarising the state-of-the-art of AM of other classes of steels. Our comprehensive review highlights that a wide range of steels can be processed by AM. The unique microstructural features including hierarchical (sub)grains and fine precipitates induced by AM result in enhancements of strength, wear resistance and corrosion resistance of AM steels when compared to their conventional counterparts. Achieving an acceptable ductility and fatigue performance remains a challenge in AM steels. AM also acts as an intrinsic heat treatment, triggering ‘in situ’ phase transformations including tempering and other precipitation phenomena in different grades of steels such as PH steels and tool steels. A thorough discussion of the performance of AM steels as a function of these unique microstructural features is presented in this review.

Compact back-scattered electrons' energy analyzer for standard SEM

1994 ◽  
Vol 52 ◽  
pp. 488-489
Author(s):  
S. Likharev ◽  
A. Kramarenko ◽  
V. Vybornov
Keyword(s):  
Depth Resolution ◽  
High Energy ◽  
Primary Beam ◽  
Layer By Layer ◽  
Energy Analyzer ◽  
High Energy Part ◽  
Small Window ◽  
Energy Part ◽  
Wide Range ◽  
High Voltage Supply

At present time the interest is growing considerably for theoretical and experimental analysis of back-scattered electrons (BSE) energy spectra. It was discovered that a special angle and energy nitration of BSE flow could be used for increasing a spatial resolution of BSE mode, sample topography investigations and for layer-by layer visualizing of a depth structure. In the last case it was shown theoretically that in order to obtain suitable depth resolution it is necessary to select a part of BSE flow with the directions of velocities close to inverse to the primary beam and energies within a small window in the high-energy part of the whole spectrum.A wide range of such devices has been developed earlier, but all of them have considerable demerit: they can hardly be used with a standard SEM due to the necessity of sufficient SEM modifications like installation of large accessories in or out SEM chamber, mounting of specialized detector systems, input wires for high voltage supply, screening a primary beam from additional electromagnetic field, etc. In this report we present a new scheme of a compact BSE energy analyzer that is free of imperfections mentioned above.

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