A macroscale FEM-based approach for selective laser sintering of thermoplastics

Ganci, Mario; Zhu, Wei; Buffa, Gianluca; Fratini, Livan; Song, Bo; Yan, Chunze

doi:10.1007/s00170-017-9998-5

Cited by 21 publications

(13 citation statements)

References 23 publications

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“…Through ray-tracing algorithms, the trajectories of the light rays, or photons, emitted by the laser source can be simulated probabilistically when travelling into the considered medium, until they hit a pre-defined area. According to the model proposed by Xin et al [93], the initial position of a photon in the laser beam section is defined in spherical coordinates by the radius and the azimuthal angle u, where the angle is distributed uniformly in the interval 0; 2p ½ , while the radius [93,94] Particle-based Semi-crystalline (PA12) Thermal [87] Analytical Semi-crystalline (PVA) Thermal [88,96] Finite elements Semi-crystalline (PA6) Thermal [89,90] Finite elements Semi-crystalline (PA12) Thermal, sintering [80,82,83,86] Finite elements Amorphous (PC) Thermal, sintering [79,81] Finite differences Amorphous (PC) Thermal, sintering [84] Finite volumes Amorphous (PC) Thermal, sintering [85,90] Finite elements Semi-crystalline (PA12) Optical, thermal, sintering [93] Particle-based Semi-crystalline (PA12) Thermal, mechanical [91,128] Finite elements Semi-crystalline (PA12) Thermal, mechanical [92] Finite elements Semi-crystalline (PP)…”

Section: Models Of the Thermal Processmentioning

confidence: 99%

“…Thermal gradients developing in the material during the AM process are among the main sources of part inaccuracy. In order to predict the expected warping of polymeric parts obtained from SLS, Ganci et al [92] adopted an elastoplastic constitutive relationship to study the influence of thermal gradients developing into the printed material (polypropylene) during cooling. However, Amado et al [91] observed that not only the temperature gradient but also the inhomogeneous crystallisation might contribute to the material shrinkage in thermoplastics.…”

Section: Models Of the Mechanical Behaviourmentioning

confidence: 99%

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Laser-based additively manufactured polymers: a review on processes and mechanical models

et al. 2020

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Additive manufacturing (AM) is a broad definition of various techniques to produce layer-by-layer objects made of different materials. In this paper, a comprehensive review of laser-based technologies for polymers, including powder bed fusion processes [e.g. selective laser sintering (SLS)] and vat photopolymerisation [e.g. stereolithography (SLA)], is presented, where both the techniques employ a laser source to either melt or cure a raw polymeric material. The aim of the review is twofold: (1) to present the principal theoretical models adopted in the literature to simulate the complex physical phenomena involved in the transformation of the raw material into AM objects and (2) to discuss the influence of process parameters on the physical final properties of the printed objects and in turn on their mechanical performance. The models being presented simulate: the thermal problem along with the thermally activated bonding through sintering of the polymeric powder in SLS; the binding induced by the curing mechanisms of light-induced polymerisation of the liquid material in SLA. Key physical variables in AM objects, such as porosity and degree of cure in SLS and SLA respectively, are discussed in relation to the manufacturing process parameters, as well as to the mechanical resistance and deformability of the objects themselves. Graphic abstract

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Section: Models Of the Thermal Processmentioning

confidence: 99%

Section: Models Of the Mechanical Behaviourmentioning

confidence: 99%

Laser-based additively manufactured polymers: a review on processes and mechanical models

et al. 2020

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“…The simulated results showed that the sintered depth was dependent on the laser power and scanning speed. Recently, Ganci et al [21] proposed a numerical approach to model the SLS of polypropylene. In their study, a 3D thermal thermomechanical model was set up to predict both the temperature fields and the distortion of the sintered parts.…”

Section: Introductionmentioning

confidence: 99%

Improvement on Selective Laser Sintering and Post-Processing of Polystyrene

et al. 2019

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Amorphous polymers are heavily utilized materials in selective laser sintering (SLS) due to their good dimensional accuracy. However, sintered parts of amorphous polymers cannot be used as functional parts owing to their poor forming performance, including their low relative densities and tensile strength. Therefore, post-processing methods are employed to enhance the mechanical properties of amorphous polymers SLS parts without damaging their relatively high dimensional accuracy. In this study, the forming process of selective laser sintering (SLS) and post-processing on polystyrene (PS) was investigated. The orthogonal experiment was designed to obtain the optimal combination of process parameters. The effect of a single process parameter and the laser volumetric energy density (LVED) on dimension accuracy and warpage of the sintered parts were also discussed. In addition, a three-dimensional (3D) thermal model was developed to analyze the temperature fields of single-layer SLS parts and PS powder sintering mechanism. Then, infiltrating with epoxy resin was employed to enhance the mechanical properties of the PS parts. Good resin-infiltrated formulation was obtained based on the mechanical property tests and fractured surface analysis. This research provides guidance for SLS process and post-processing technology in polymers.

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“…The current state-of-the-art [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] describes the importance of part orientation, powder morphology, and machine process parameters as a means towards the control and management of variation in polymer powder bed fusion system. Among the most investigated additive manufacturing (AM) machine process parameters are laser power, scan speed, hatch distance, scan strategy, beam speed, melting temperature, and powder bed temperature [2][3][4][5][6][7]. There is a number of studies [20][21][22] which report that laser power, scan speed, hatch distance, and layer thickness can be used to define the line energy and how their variation may influence mechanical properties of the part.…”

Section: Introductionmentioning

confidence: 99%

Application of Machine Learning Techniques to Predict the Mechanical Properties of Polyamide 2200 (PA12) in Additive Manufacturing

Baturynska

2019

Applied Sciences

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Additive manufacturing (AM) is an attractive technology for the manufacturing industry due to flexibility in its design and functionality, but inconsistency in quality is one of the major limitations preventing utilizing this technology for the production of end-use parts. The prediction of mechanical properties can be one of the possible ways to improve the repeatability of results. The part placement, part orientation, and STL model properties (number of mesh triangles, surface, and volume) are used to predict tensile modulus, nominal stress, and elongation at break for polyamide 2200 (also known as PA12). An EOS P395 polymer powder bed fusion system was used to fabricate 217 specimens in two identical builds (434 specimens in total). Prediction is performed for XYZ, XZY, ZYX, and Angle orientations separately, and all orientations together. The different non-linear models based on machine learning methods have higher prediction accuracy compared with linear regression models. Linear regression models only have prediction accuracy higher than 80% for Tensile Modulus and Elongation at break in Angle orientation. Since orientation-based modeling has low prediction accuracy due to a small number of data points and lack of information about the material properties, these models need to be improved in the future based on additional experimental work.

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A macroscale FEM-based approach for selective laser sintering of thermoplastics

Cited by 21 publications

References 23 publications

Laser-based additively manufactured polymers: a review on processes and mechanical models

Laser-based additively manufactured polymers: a review on processes and mechanical models

Improvement on Selective Laser Sintering and Post-Processing of Polystyrene

Application of Machine Learning Techniques to Predict the Mechanical Properties of Polyamide 2200 (PA12) in Additive Manufacturing

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