Multiscale Modeling of the Laser Additive Manufacturing Process

Multiscale Modeling of the Laser Additive Manufacturing Process

Seshadev Sahoo (Siksha O Anusandhan (Deemed), India) and Jyotirmoy Nandy (Siksha O Anusandhan (Deemed), India)
Copyright: © 2020 |Pages: 14
DOI: 10.4018/978-1-7998-4054-1.ch012
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Abstract

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.
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Introduction

In the recent era, the manufacturing industries face global competition to fabricate their product in reduced time with high quality and low cost. With this aim, Rapid Prototyping technologies have been developed to overcome this issue. In other names, rapid prototyping is also referred to as 3D printing or Additive Manufacturing (AM). Today this AM emerges as one of the smart manufacturing technologies which allow parts to be manufactured through a layer-by-layer build strategy. This technology has been shown its capability in various industrial sectors ranging from the medical industry to the aerospace industry to make near net shape components such that fuel injector nozzle, medical and dental implants, punches, dies, and custom tooling (Guo & Leu, 2013). The components produced by the AM process offers a significant improvement in integration, mechanical properties, lifetime, and energy savings. In comparison with the traditional manufacturing processes, AM processes are a layer-based method that fabricated near net shape components with a predefined digital CAD model without the need for expensive tools. This process utilizes a high-frequency mobile source of heat to produce fully dense components. The advantages of the AM processes over conventional manufacturing methods are design freedom, rapid and cost-effective, ability to produce topologically optimized structure, and also low volume manufacturing of components. The AM processes can permit a high level of flexibility in comparison to the cost of production and time of processing of older traditional processes. Thus, manufacturing industries are exhibiting a huge amount of interest inapplicability of the AM process. The major classifications in currently available in AM technologies are (i) laser sintering (ii) laser melting, (iii) direct energy deposition (Nandy et al., 2019; Frazier, 2014). These classifications consist of various techniques of production based on the type of materials, consolidation method and its mechanism, and the source of energy used.

To meet the requirements for the production of high quality end-use metallic parts, AM processes are been developed with each passing year to make the process more efficient. Although this process can process and manufacture a wide range of metals, AM also excels in the manufacture of high-quality ceramics and composites. The quality of final products manufactured using AM techniques is dependent on internal properties such as the emerging microstructure, amount of pore formation, distribution of stress, rise in internal defects, and other important physical properties. The properties of finished products such as mechanical strength, morphology, and structural growth depend upon initial process parameters. Previous literature on AM techniques demonstrates that several kinds of heat, as well as mass transfer, take place throughout the process, which gives rise to complicated mechanical behavior in the finished specimens. These behaviors are governed by both the physical and chemical properties of the material used. Important characteristics including shape and size of particle, porosity, flowability, composition, and processing conditions play an essential part in the quality of the finished product. As the final microstructure affects both the mechanical and physical aspects of the finished products, research worldwide recommends the computational modeling of microstructures (Mayer, 2005). This helps in predicting the structural changes and final properties of different materials throughout different AM processes. The recent market has shown a huge interest in computational modeling as it helps in qualitative improvement of the samples and reduces material wastage.

This chapter intends to provide a detailed knowledge of multiscale computational modeling used for AM techniques. In this chapter, the classification of AM techniques is shown which is then followed by computational modeling in one of the widely used AM processes called direct metal laser sintering (DMLS). This chapter consists of three different modeling techniques at different length scales. Comprehensive knowledge of microstructure modeling is provided which will help researchers to adopt computational modeling for different AM techniques.

Key Terms in this Chapter

Solidification: Solidification, also known as freezing, is a phase change of matter that results in the production of a solid, when the temperature of a liquid is lowered below its freezing point.

LAMMPS: Large scale atomic/molecular massively parallel simulator platform used for atomistic simulation of material systems.

Sintering: The process where compaction of powder particles takes place into solid mass by the application of heat and pressure without melting.

Direct Metal Laser Sintering: It is powder based additive manufacturing process that has the potential to make the metallic components from powder particles.

Laser Energy Density: It is defined as laser energy concentrated per unit volume.

Coalescence: The particles agglomerates changes from uneven shapes to more monolithic, spherical shapes.

Additive Manufacturing: It is an advance manufacturing process which fabricates components in a layered fashion by fusing the powder particles.

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