Accelerating heat transfer modeling in material extrusion additive manufacturing: From desktop to big area

Owens, James; Das, Arit; Bortner, Michael J.

doi:10.1016/j.addma.2022.102853

Cited by 8 publications

(5 citation statements)

References 54 publications

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“…This adjustment allows the various sections of the same print to dissipate heat at the same rates. [ 186 ] Also, several issues are related to the printer's process parameters and thermal properties in both AM and BAAM. For these thermally driven processes, the variation in size scale results in significant variances in thermal behavior.…”

Section: Discussionmentioning

confidence: 99%

Mechanical characterization of additively manufactured polymer composites: A state‐of‐the‐art review and future scope

Darji,

Singh,

Mali

2023

Polymer Composites

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The additive manufacturing (AM) technology can manufacture complex parts with considerable improvements in lead times and lower material wastages. It has enabled technological advances across many domains, from space to medical devices. The polymer composites fabricated through AM have tremendous advantages over conventional polymers in terms of mechanical performance and are, therefore, better suited for producing functional parts and assemblies. However, AM of polymer composites still presents several technological obstacles that prevent their full commercial utilization. These challenges include limited combinations of matrix and reinforcements, a requirement for hardware modification of existing machines, and challenges in mechanical characterization. This article attempts to comprehensively review the fundamentals and features of contemporary additively manufactured polymer composites (AMPCs) and examines current cutting‐edge research and development. This review highlights the gaps in the mechanical characterization of polymer composites fabricated through various technologies like material extrusion, vat‐photopolymerization, binder jetting, material jetting, powder bed fusion, and sheet lamination. There is a need to fill the identified research gaps to make AMPCs more appealing for widespread industrial use for advanced applications.

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Section: Discussionmentioning

confidence: 99%

Mechanical characterization of additively manufactured polymer composites: A state‐of‐the‐art review and future scope

Darji,

Singh,

Mali

2023

Polymer Composites

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“…However, the authors are unaware of any processstructure-property relationship development research in thermoplastic LFAM. Previous work by Owens et al (2022) shows a significant difference in temperatures, dominant heat transfer terms, and other processing conditions for LFAM compared to small-scale AM, highlighting the need for LFAM-specific process-structure-property mapping [17]. Owens et al developed a reduced dimension numerical model to simulate the thermal behavior of fused filaments in small-scale AM and in LFAM.…”

Section: Introductionmentioning

confidence: 99%

Process–Structure–Property Relationship Development in Large-Format Additive Manufacturing: Fiber Alignment and Ultimate Tensile Strength

Slattery,

McClelland,

Hess

2024

Materials

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Parts made through additive manufacturing (AM) often exhibit mechanical anisotropy due to the time-based deposition of material and processing parameters. In polymer material extrusion (MEX), printed parts have weak points at layer interfaces, perpendicular to the direction of deposition. Poly(lactic acid) with chopped carbon fiber was printed on a large-format pellet printer at various extrusion rates with the same tool pathing to measure the fiber alignment with deposition via two methods and relate it to the ultimate tensile strength (UTS). Within a singular printed bead, an X-ray microscopy (XRM) scan was conducted to produce a reconstruction of the internal microstructure and 3D object data on the length and orientation of fibers. From the scan, discrete images were used in an image analysis technique to determine the fiber alignment to deposition without 3D object data on each fiber’s size. Both the object method and the discrete image method showed a negative relationship between the extrusion rate and fiber alignment, with −34.64% and −53.43% alignment per extrusion multiplier, respectively, as the slopes of the linear regression. Tensile testing was conducted to determine the correlation between the fiber alignment and UTS. For all extrusion rates tested, as the extrusion multiplier increased, the percent difference in the UTS decreased, to a minimum of 8.12 ± 14.40%. The use of image analysis for the determination of the fiber alignment provides a possible method for relating the microstructure to the meso-property of AM parts, and the relationship between the microstructure and the properties establishes process–structure–property relationships for large-format AM.

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“…The increase in deposited volume, combined with the low thermal conductivity of thermoplastics, means that the heat energy supplied remains stored in the material for a longer time. In addition, the larger volume requires the consideration of the temperature gradient in the material, which can be quantified by the Biot number [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Crystallisation Dynamics in Large-Scale Extrusion Additive Manufacturing: An Analysis with and without Temperature Modification

Leubecher,

Brier,

Vitale

et al. 2024

Materials

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Large-Scale Material Extrusion (LS-MEX) is increasingly being used in small-scale production and prototyping due to its ability to create components in new temporal and spatial dimensions. However, the use of this manufacturing process poses microscopic and macroscopic challenges not encountered in previous small-scale production systems. These challenges arise primarily from the prolonged retention of heat in the material, which leads to insufficient strength in the extruded strands at the macrostructural level. As a result, the component can collapse, a phenomenon known as ‘slumping’. Thermal energy also influences microstructural changes, such as crystallisation kinetics, which affect properties such as the strength and stiffness of the final product. The duration and dynamics of thermal energy are influenced by manufacturing parameters and the possible use of additional peripheral equipment, which affects component quality. In this study, the influence of thermal energy on structural processes through simulations of polyamide 6 with 40% carbon fibres (PA6 wt.%40 CF) is investigated. The results show that by adjusting the process parameters and using modification units, the thermal profile of the material can be accurately controlled, which allows the microstructural processes to be precisely controlled. This leads to the targeted modification of the macroscopic material properties. The focus of this work is on the combination of numerical simulations of the LS-MEX process with semi-empirical methods for the analysis of crystallisation processes. The application of the Nakamura model, which is used throughout similar investigations, allows a detailed description and prediction of the crystallisation kinetics during the manufacturing process. The study shows that the absolute degree of crystallisation can be determined with simplified assumptions using a combination of thermal simulations and semi-empirical approaches. It was found that the absolute degree of crystallisation increases from the outer interface of the strand to the print bed across the cross-section. This can be attributed to the specific thermal boundary conditions and the resulting temperature profiles at different points.

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Accelerating heat transfer modeling in material extrusion additive manufacturing: From desktop to big area

Cited by 8 publications

References 54 publications

Mechanical characterization of additively manufactured polymer composites: A state‐of‐the‐art review and future scope

Mechanical characterization of additively manufactured polymer composites: A state‐of‐the‐art review and future scope

Process–Structure–Property Relationship Development in Large-Format Additive Manufacturing: Fiber Alignment and Ultimate Tensile Strength

Crystallisation Dynamics in Large-Scale Extrusion Additive Manufacturing: An Analysis with and without Temperature Modification

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