Journal articles: 'Selective heat sintering'

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Yu, Yue Qiang, Yan Ling Guo, and Kai Yi Jiang. "Temperature Field Simulation of Wood Powder/PES Composite Powder Material." Key Engineering Materials 667 (October 2015): 218–23. http://dx.doi.org/10.4028/www.scientific.net/kem.667.218.

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In view of the physical process of the wood powder/PES composite powder material selective laser sintering forming ,this article establishes the plane moving Gaussian heat source as the input laser heat source model .Based on selective laser sintering wood powder/PES composite powder sintering theory and combined with thermal conductivity of composite powder, specific heat, density and other related theoretical analytical models .It establishes three dimensional finite element model of selective laser sintering process of wood powder/PES composite powder transient temperature field .The laser sintering simulation experiment of wood powder/PES composite powder under different laser power obtains temperature field distribution law of the wood powder/PES composite powder forming under different laser power distribution, and the influence of the forming parts forming quality of wood powder/PES composite powder materials caused by the temperature field. The simulation results also provide certain theoretical basis for the choice of laser power in the subsequent laser sintering experiment.

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Dong, Lin, Ahmed Makradi, Saïd Ahzi, and Yves Remond. "Finite Element Analysis of Temperature and Density Distributions in Selective Laser Sintering Process." Materials Science Forum 553 (August 2007): 75–80. http://dx.doi.org/10.4028/www.scientific.net/msf.553.75.

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In the selective laser sintering (SLS) manufacturing technique a pre-heated layer of material powder undergoes a laser radiation in a selective way to produce three dimensional metallic or polymeric solid parts. Here, we consider sintering of polymer powder. The phase transformation in this process involves the material heat transfer which is strongly affected by the material sintering phenomena. A transient three dimensional finite element model is developed to simulate the phase transformation during the selective laser sintering process. This model takes into account the heat transfer in the material (powder and solid), the sintering and the transient nature of this process. The numerical simulation of the set of equations, describing the problem, is made possible by means of the commercial finite element software Abaqus. A bi-level structure integration procedure is chosen, in which the density is integrated at the outer level and the heat equation is integrated in the inner level. After successfully computing the integration of the density, a material Jacobian representing the thermal phenomena is computed and supplemented the Abaqus Code via an implicit user subroutine material. Results for temperature and density distribution, using a polycarbonate powder, are presented and discussed.

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Yang, Zhiyong, Xing Liu, Zihao Zhang, Shuting Li, and Qiao Fang. "Analysis of preheating temperature field characteristics in selective laser sintering." Advances in Mechanical Engineering 14, no. 1 (January 2022): 168781402110723. http://dx.doi.org/10.1177/16878140211072397.

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Selective laser sintering technology has broad application prospects in the manufacture of small batch parts with complex structure. In the sintering process, the preheating efficiency and temperature of powder layer determine the processing quality. A method of preheating powder by lamp radiation and tropical heat conduction is proposed in this paper. The thermal radiation model is established, and the angle coefficient is introduced to describe the proportion of radiation energy on the surface of powder layer. Based on the geometric characteristics of the powder cylinder, the heat conduction process is simplified to one-dimensional heat conduction along the radial direction, and the heat conduction model is established. The coupled temperature field under two actions is obtained by combining the heat radiation model with the heat conduction model. The uniformity coefficient [Formula: see text]/[Formula: see text] of the temperature field is defined to represent the uniformity of the preheating temperature field of the powder layer. By comparing the uniformity coefficient [Formula: see text], a more uniform temperature field can be obtained when the height coefficient is 1.8 under combined action. The validity of the model is verified by a comparative experiment with processed water atomized iron powder. Constructing uniform temperature field can effectively reduce the deformation of parts and improve the forming quality.

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Deepak Kumar, K., N. Prasanth, P. Arunkumar, Esakki Balasubramanian, and A. Abilash. "Coupled Field Transient Thermo - Structural Analysis of Inhibited Sintering Process." Applied Mechanics and Materials 813-814 (November 2015): 663–67. http://dx.doi.org/10.4028/www.scientific.net/amm.813-814.663.

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Proliferation in the use of digital data in manufacturing led to a new industrial revolution by virtue of which user groups and researchers from multiple industrial enterprises have introduced Rapid Prototyping (RP) into their product development processes. This paper presents a coupled field thermos-structural analysis of new RP process namely, Selective Inhibition Sintering Process (SISP) for the evaluation on the effect of temperature in various polymer materials. The present study provides information of the requirement of heat source to achieve effective sintering phenomenon. The structured Finite Element (FE) model with a dimension of 30 X 30 X 1.5 mm is considered for the analysis where in different heat quantity is applied in an iterative manner to examine the sintering temperature. Based on the simulation results, for each polymer, required amount of heat to observe sintering characteristics is evaluated. The effect of applied heat on the examination of structural aspects of polymer materials including thermal stress, distortion and displacement is carried out. The simulation results affirms that the polymer materials are within in the safe structural and thermal limit and the selection of low cost heat source will be useful for the development of cost-effective SISP system.

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Zhang, Jian, De Ying Li, Wei Fu, and Long Zhi Zhao. "Numerical Simulation of Multi-Component Powder in Selective Laser Sintering." Advanced Materials Research 139-141 (October 2010): 630–33. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.630.

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The process of sintering material from the powder to the liquid with high temperature and then to the continuous solid are simulated, considering the effects of heat conduction, thermal radiation, thermal convection and thermal physical parameters on temperature. The results show that the temperature gradient is larger in the front of pool, and the end of which is smaller due to the fast-moving laser beam and uneven distribution of laser energy. With the increase of scanning time, the overall temperature of substrate and powder particles is gradually rising, the heat-affected zone is increasing and the asymmetric temperature distribution has become more obvious for the heat conduction. As the pool depth is larger than the powder thickness and the pool width is larger than the scanning spacing at the current process parameters, the bond strength of layers and scanning lines is enough.

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Zhang, Jian, De Ying Li, Bin Qiu, and Long Zhi Zhao. "Simulation of Temperature Field in Selective Laser Sintering on PA6/Cu Composite Powders." Advanced Materials Research 213 (February 2011): 519–23. http://dx.doi.org/10.4028/www.scientific.net/amr.213.519.

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The 3D transient finite element model in selective laser sintering is established based on ANSYS. The load of moving heat source at different time and locations are achieved by APDL and “element birth/death” technique, and the influence of convection, radiation, latent heat of phase change and thermal physical properties on temperature are taken into account. The temperature field distribution on time in forming process and temperature gradient distributions of pool cross-section are selectively studied, to provide theoretical basis for reasonable process parameters. The SLS experiment on PA6/Cu composite powders is carried out to verify the accuracy of simulation results.

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CHEN, Songtao. "Efficient Meshfree Method for Heat Conduction in Selective Laser Sintering Process." Journal of Mechanical Engineering 55, no. 7 (2019): 135. http://dx.doi.org/10.3901/jme.2019.07.135.

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Tolochko, Nikolay K., Maxim K. Arshinov, Andrey V. Gusarov, Victor I. Titov, Tahar Laoui, and Ludo Froyen. "Mechanisms of selective laser sintering and heat transfer in Ti powder." Rapid Prototyping Journal 9, no. 5 (December 2003): 314–26. http://dx.doi.org/10.1108/13552540310502211.

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Yaagoubi, Hanane, Hamid Abouchadi, and Mourad Taha Janan. "Simulation of the Heat Laser of the Selective Laser Sintering Process of the Polyamide12." E3S Web of Conferences 297 (2021): 01050. http://dx.doi.org/10.1051/e3sconf/202129701050.

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Laser sintering sintering is one of the most widely used 3D printing technologies, in which it transforms 3D models into authentic parts with generally excellent workmanship, the test today is to ensure the unmatched nature of the item produced, therefore hypothetically to understand and predict the thermal history in this process, the thermal models must be exact and fair, In this article, the consideration will be focused on the different models of heat flux diffusion, in the bibliography, some formulas Numbers that describe the transport of the heat source out of the powder bed have been found. A comparison between its laser source models will be established. The re-modeling takes place in MATLAB using the parameters of polyamide12.

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Chen, Tiebing, and Yuwen Zhang. "Three-Dimensional Modeling of Selective Laser Sintering of Two-Component Metal Powder Layers." Journal of Manufacturing Science and Engineering 128, no. 1 (July 16, 2005): 299–306. http://dx.doi.org/10.1115/1.2122947.

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Laser sintering of a metal powder mixture that contains two kinds of metal powders with significantly different melting points under a moving Gaussian laser beam is investigated numerically. The continuous-wave laser-induced melting accompanied by shrinkage and resolidification of the metal powder layer are modeled using a temperature-transforming model. The liquid flow of the melted low-melting-point metal driven by capillary and gravity forces is also included in the physical model. The numerical results are validated by experimental results, and a detailed parametric study is performed. The effects of the moving heat source intensity, the scanning velocity, and the thickness of the powder layer on the sintering depth, the configuration of the heat affected zone, and the temperature distribution are discussed.

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Polychronopoulos, Nickolas D., and John Vlachopoulos. "The role of heating and cooling in viscous sintering of pairs of spheres and pairs of cylinders." Rapid Prototyping Journal 26, no. 4 (January 31, 2020): 719–26. http://dx.doi.org/10.1108/rpj-06-2019-0162.

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Purpose This study aims to develop mathematical models for the determination of the effects of heating or cooling on neck growth in Selective Laser Sintering (SLS) and Fused Filament Fabrication (FFF). Two particle shapes are studied: spherical and cylindrical. Design/methodology/approach The time required for the coalescence (sintering) process is determined by balancing the work of surface tension forces and viscous dissipation. Heating and cooling effects are studied by incorporating temperature dependence of viscosity in an exponential form. Heating by a laser, convective and/or radiative heat transfer is assumed. It is also assumed that there are no temperature gradients within the coalescing molten polymers (lumped parameter heat transfer analysis). Findings The models predict faster sintering with heating and slower with cooling, as expected because of the effect of temperature on viscosity. For the isothermal case of pairs of cylinders, the present model predicts significantly longer time for completion of sintering than a previously developed and frequently cited model by Hopper. Originality/value An isothermal sintering model for two spheres was reworked for two long cylinders, and for the first time it has been compared to other models available in the literature. The mathematical models are capable of predicting neck growth under non-isothermal conditions for both spheres and cylinders. They are useful in assessment of bonding in selective laser sintering and fused deposition fabrication.

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Xiao, K., K. W. Dalgarno, D. J. Wood, R. D. Goodridge, and C. Ohtsuki. "Indirect selective laser sintering of apatite—wollostonite glass—ceramic." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 222, no. 7 (October 1, 2008): 1107–14. http://dx.doi.org/10.1243/09544119jeim411.

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This paper develops an indirect selective laser sintering (SLS) processing route for apatite—wollastonite (A—W) glass—ceramic, and shows that the processing route, which can create porous three-dimensional products suitable for bone implants or scaffolds, does not affect the excellent mechanical and biological properties of the glass—ceramic. ‘Green parts’ with fine integrity and well-defined shape have been produced from glass particles of single-size range or mixed-size ranges with acrylic binder in various ratios by weight. A subsequent heat treatment process has been developed to optimize the crystallization process, and an infiltration process has been explored to enhance mechanical strength. Three-point bending test results show flexural strengths of up to 102 MPa, dependent on porosity, and simulated body fluid (SBF) tests show that the laser sintered porous A—W has comparable biological properties to that of conventionally produced A—W.

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D, Rajamani, and E. Balasubramanian. "Effects of heat energy on morphology and properties of selective inhibition sintered high density polyethylene." Journal of Mechanical Engineering and Sciences 13, no. 1 (March 28, 2019): 4403–14. http://dx.doi.org/10.15282/jmes.13.1.2019.05.0375.

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This study provides an account of comprehensive experimentation and mechanical characterisation of high density polyethylene (HDPE) parts that are fabricated through an additive manufacturing process called selective inhibition sintering (SIS). In this study, test specimens are fabricated by selective fusing of HDPE particles through controlled heating. Morphological studies and mechanical property evaluation of these specimens are carried out to assess the impact of energy on sintering of HDPE particles and structural integrity. Results indicate that, heat energy up to a threshold level of 28.48 J/mm2 results in superior fusion of the HDPE particles, and further increase causes degradation of the structure. Surface roughness, tensile and flexural properties of SIS parts are compared with those of injection moulded parts for assessing their suitability to engineering applications.

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Mal’tzev, I. E., A. A. Basov, M. A. Borisov, and A. V. Bystrov. "STUDY OF THE PROPERTIES A FRAGMENT OF THE HYDRAULIC CIRCUIT OF THE SPACECRAFT, OBTAINED BY MEANS OF ADDITIVE TECHNOLOGIES." Spravochnik. Inzhenernyi zhurnal, no. 277 (April 2020): 11–19. http://dx.doi.org/10.14489/hb.2020.04.pp.011-019.

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The article discusses the course and results of experimental work on the initial study of the possibility of using one of the varieties of additive technologies – the method of layer-by-layer selective laser melting (SLM) in the manufacture of elements of heat exchangers and hydraulic circuits of spacecraft. Traditional manufacturing techniques for hydro-control elements and spacecraft heat exchangers are based on machining and high-temperature vacuum soldering, leading to a long cycle and high manufacturing costs. As an alternative, the method of layer-by-layer selective laser melting can be considered as a manufacturing method using a three-dimensional model of the product and not requiring additional equipment. This method is based on sequential layer-by-layer fusion of a metal powder with previous fused product layers under the action of a laser beam forming a local region of liquid melt. The article describes experimental work to assess the possibility of using the selective laser melting method. Assessed weld-ability of a sample made by selective laser fusion technology with tips made by traditional technology. Directions for testing the method of selective laser sintering on real structures of heat exchanging units of spacecraft have been determined. A technique is proposed and the results of a study of a sample synthesized by selective laser sintering are presented. Based on the results obtained, an analysis is made of the prospects for using this method in the production of elements of hydraulic circuits and heat exchange units of spacecraft.

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Mal’tzev, I. E., A. A. Basov, M. A. Borisov, and A. V. Bystrov. "STUDY OF THE PROPERTIES A FRAGMENT OF THE HYDRAULIC CIRCUIT OF THE SPACECRAFT, OBTAINED BY MEANS OF ADDITIVE TECHNOLOGIES." Spravochnik. Inzhenernyi zhurnal, no. 277 (April 2020): 11–19. http://dx.doi.org/10.14489/hb.2020.04.pp.011-019.

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The article discusses the course and results of experimental work on the initial study of the possibility of using one of the varieties of additive technologies – the method of layer-by-layer selective laser melting (SLM) in the manufacture of elements of heat exchangers and hydraulic circuits of spacecraft. Traditional manufacturing techniques for hydro-control elements and spacecraft heat exchangers are based on machining and high-temperature vacuum soldering, leading to a long cycle and high manufacturing costs. As an alternative, the method of layer-by-layer selective laser melting can be considered as a manufacturing method using a three-dimensional model of the product and not requiring additional equipment. This method is based on sequential layer-by-layer fusion of a metal powder with previous fused product layers under the action of a laser beam forming a local region of liquid melt. The article describes experimental work to assess the possibility of using the selective laser melting method. Assessed weld-ability of a sample made by selective laser fusion technology with tips made by traditional technology. Directions for testing the method of selective laser sintering on real structures of heat exchanging units of spacecraft have been determined. A technique is proposed and the results of a study of a sample synthesized by selective laser sintering are presented. Based on the results obtained, an analysis is made of the prospects for using this method in the production of elements of hydraulic circuits and heat exchange units of spacecraft.

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Yang, Lai Xia, Kun Bao, Cheng He, and Di Chen Li. "Research on the Method of Microwave Curing in Selective Laser Sintering." Applied Mechanics and Materials 271-272 (December 2012): 1110–14. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1110.

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Curing process takes play an important role in the selective laser sintering. The advantage and disadvantage of several traditional curing processes was firstly analyzed in this paper. And then the collapse, warping and cracking of coated sand parts in the microwave curing process were studied by experiments and also the solutions was put forward. Using microwave heat to curing coated sand parts is not only high efficiency,energy saving and environmental protection, but also reduced the shrinking and the defect rate of the parts in the curing process.

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Yaagoubi, Hanane, Hamid Abouchadi, and Mourad Taha Janan. "Numerical simulation of heat transfer in the selective laser sintering process of Polyamide12." Energy Reports 7 (November 2021): 189–99. http://dx.doi.org/10.1016/j.egyr.2021.08.089.

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Zacharatos, Filimon, Ioannis Theodorakos, Panagiotis Karvounis, Simon Tuohy, Nuno Braz, Semyon Melamed, Ayala Kabla, et al. "Selective Laser Sintering of Laser Printed Ag Nanoparticle Micropatterns at High Repetition Rates." Materials 11, no. 11 (October 31, 2018): 2142. http://dx.doi.org/10.3390/ma11112142.

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The increasing development of flexible and printed electronics has fueled substantial advancements in selective laser sintering, which has been attracting interest over the past decade. Laser sintering of metal nanoparticle dispersions in particular (from low viscous inks to high viscous pastes) offers significant advantages with respect to more conventional thermal sintering or curing techniques. Apart from the obvious lateral selectivity, the use of short-pulsed and high repetition rate lasers minimizes the heat affected zone and offers unparalleled control over a digital process, enabling the processing of stacked and pre-structured layers on very sensitive polymeric substrates. In this work, the authors have conducted a systematic investigation of the laser sintering of micro-patterns comprising Ag nanoparticle high viscous inks: The effect of laser pulse width within the range of 20–200 nanoseconds (ns), a regime which many commercially available, high repetition rate lasers operate in, has been thoroughly investigated experimentally in order to define the optimal processing parameters for the fabrication of highly conductive Ag patterns on polymeric substrates. The in-depth temperature profiles resulting from the effect of laser pulses of varying pulse widths have been calculated using a numerical model relying on the finite element method, which has been fed with physical parameters extracted from optical and structural characterization. Electrical characterization of the resulting sintered micro-patterns has been benchmarked against the calculated temperature profiles, so that the resistivity can be associated with the maximal temperature value. This quantitative correlation offers the possibility to predict the optimal process window in future laser sintering experiments. The reported computational and experimental findings will foster the wider adoption of laser micro-sintering technology for laboratory and industrial use.

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Kandis, M., C. W. Buckley, and T. L. Bergman. "An Engineering Model for Laser-Induced Sintering of Polymer Powders." Journal of Manufacturing Science and Engineering 121, no. 3 (August 1, 1999): 360–65. http://dx.doi.org/10.1115/1.2832689.

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Laser-induced sintering of powders has become prevalent in a number of Solid Freeform Fabrication technologies such as Selective Laser Sintering (SLS), which is used to produce nearly solid parts from initially-porous powder via laser irradiation. In this paper, a model is presented which can be used to predict the shape and general features of consolidated heat affected zones produced by laser-induced, non-isothermal sintering of polymer powder. Comparisons between experimental results and predictions are made, and the model is used to investigate the influence of various thermal processing parameters on the sintering operation. The model is then extended to simulate the manufacture of a simple multiple layer part which is produced in a manner similar to SLS.

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Murawski, K., K. Aristovich, and H. T. Lancashire. "Selective laser sintering of glass-ceramic bonds using a defocused Nd:YAG laser." International Symposium on Microelectronics 2020, no. 1 (September 1, 2020): 000286–90. http://dx.doi.org/10.4071/2380-4505-2020.1.000286.

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Abstract Protecting miniature implantable electronics may require mm scale hermetic packages. Glass-ceramic bonding by selective laser sintering of glass sealing paste using a defocused Nd:YAG laser is presented. Glass sealing paste (FX11-036, Ferro) is screen printed onto alumina ceramic, clamped in contact with borosilicate glass, and laser treated while heating to 250°C. With the addition of defocusing and a heat source the glass paste reflowed and wetted both the alumina and coverslip surfaces, with an optimal effect between 10 mm and 15 mm defocusing. This method is promising to create electrically non-conductive hermetic seals at the mm scale.

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Wu, Jinzhe, Runhuai Yang, Jinjin Zheng, and Xiang Wang. "Super heat deflection resistance stereocomplex crystallisation of PLA system achieved by selective laser sintering." Micro & Nano Letters 13, no. 11 (November 2018): 1604–8. http://dx.doi.org/10.1049/mnl.2018.5134.

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Oglezneva, Svetlana, and Almaz Khanov. "Properties of Powders from Stainless and Heat Resistant Alloys Produced by Gas Dynamic Spray for Manufacturing Parts of Complex Shape." Key Engineering Materials 746 (July 2017): 148–53. http://dx.doi.org/10.4028/www.scientific.net/kem.746.148.

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The objects of the study were powders of stainless steel and superalloy obtained gas-dynamic spray in the VIGA 2B (ALD, Germany). It have been investigated the microstructure, structural and phase composition, grain size, physical, chemical and technological properties of powders of alloys obtained by gas-dynamic spray melts.To study the structure and properties of powders of different factions were the used electron microscopy techniques, metallographic, sedimentation, X-ray, energy dispersive analysis, imaging, chemical, and other analytical methods. The powders have a spherical shape, low impurity content, good fluidity and can be used for producing parts by selective laser sintering, slip casting, injection molding, coating plasma and the sintering.

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Kim, Minha, Hongsub Jee, and Jaehyeong Lee. "Photo-Sintered Silver Thin Films by a High-Power UV-LED Module for Flexible Electronic Applications." Nanomaterials 11, no. 11 (October 25, 2021): 2840. http://dx.doi.org/10.3390/nano11112840.

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In recent printed electronics technology, a photo-sintering technique using intense pulsed light (IPL) source has attracted attention, instead of conventional a thermal sintering process with long time and high temperature. The key principle of the photo-sintering process is the selective heating of a thin film with large light absorption coefficients, while a transparent substrate does not heat by the IPL source. Most research on photo-sintering has used a xenon flash lamp as a light source. However, the xenon flash lamp requires instantaneous high power and is unsuitable for large area applications. In this work, we developed a new photo-sintering system using a high-power ultraviolet light emitting diode (UV-LED) module. A LED light source has many merits such as low power consumption and potential large-scale application. The silver nanoparticles ink was inkjet-printed on a polyethylene terephthalate (PET) and photo-sintered by the UV-LED module with the wavelength of 365 and 385 nm. The electrical resistivity as low as 5.44 × 10−6 Ω·cm (just about three times compared to value of bulk silver) was achieved at optimized photo-sintering conditions (wavelength of 365 nm and light intensity of 300 mW/cm2).

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Balaykin, Andrey V., Ekaterina A. Nosova, and Natalia V. Galkina. "The Study of the Ageing Impact on Workability and Hardness of the Samples Made of Alloy VV751P (Ni-15Co-10Cr) after Selective Laser Sintering." Key Engineering Materials 746 (July 2017): 192–97. http://dx.doi.org/10.4028/www.scientific.net/kem.746.192.

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Work is focused on study of workability changing of heat resistant nickel-based Ni-15Co-10Cr alloy produced by selective laser sintering from metal powder. Experimental research of HRC hardness changing was provided on plate samples 2х10х30 mm after sintering and typical heat treatment for this alloy. Heat treatment was: annealing at temperature of 1,000oС during 1.5 hours, and then at the temperature of 1,180oC for 2.5 h – 3 h. After that samples were treated in a furnace for 50 – 60 minutes at the temperature of 1,050oС. Then they were cooled-off to the temperature of 1,000oС during 50 – 60 minutes. After that they were further quenched at ambient temperature. After quenching the samples were subjected to ageing at the temperature of 850oC during 3, 6, 9, 12 and 15 hours. The bending and measurement of triangle height was proposed for work ability assessment of samples. Increased hardness was found with duration of ageing. Work ability grew up with duration of ageing but where was a gap of workability for 9 hours ageing. Calibration of sintered parts and samples are recommended to perform after quenching and ageing at 850oC no longer 6 hours.

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Ren, Nai Fei, Lei Jia, and Dian Wang. "Numerical Simulation Analysis on the Temperature Field in Indirect Selective Laser Sintering of 316L." Advanced Materials Research 711 (June 2013): 209–13. http://dx.doi.org/10.4028/www.scientific.net/amr.711.209.

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Using APDL programming language, an appropriate finite element model is created and the moving cyclic loads of Gauss heat source are realized. From the detailed qualitative analysis of the results, the variety laws of temperature field in indirect SLS are obtained. Plot results at different moments, temperature cyclic curves of key points and the curves of depth of fusion and width of fusion on the set paths, are of important guiding significance for subsequent physical experiments.

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Dayal, Ram, Tatiana Gambaryan-Roisman, and Eberhard Abele. "HEAT TRANSFER, PHASE CHANGE, AND COALESCENCE OF PARTICLES DURING SELECTIVE LASER SINTERING OF METAL POWDERS." Computational Thermal Sciences 4, no. 5 (2012): 411–23. http://dx.doi.org/10.1615/computthermalscien.2012005795.

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Liu, Bing, Li-chao Zhang, Jian-hua Mo, and Bo Qian. "New method of improving parts accuracy by adding heat balance support in selective laser sintering." Journal of Zhejiang University-SCIENCE A 10, no. 3 (March 2009): 361–69. http://dx.doi.org/10.1631/jzus.a0820226.

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Tian, Xiaoyong, Gang Peng, Mengxue Yan, Shunwen He, and Ruijuan Yao. "Process prediction of selective laser sintering based on heat transfer analysis for polyamide composite powders." International Journal of Heat and Mass Transfer 120 (May 2018): 379–86. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2017.12.045.

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Yaagoubi, H., and H. Abouchadi. "A three dimensional meshfree-simulation of the selective laser sintering process with constant thermal coefficients applied to nylon 12 powders." MATEC Web of Conferences 286 (2019): 04003. http://dx.doi.org/10.1051/matecconf/201928604003.

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3D printing is an intersting process in the context of creating original objects. Selective laser sintering printers use a laser to fuse polyamide particles together with specific resin and heat. The difference in temperature between the different areas in the process causes the appearance of deformations, the objective of this work is the modeling of the thermal SLS phenomenona, by following the evolution of the temperature as a function of time.This model is based on the resolution of the heat conduction equation coupling with convection and radiation conditions with a distribution heat source and constant thermal coefficients by the meshless method based on radial basis function , the result of this study,will be presented and compared with other works.

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Chen, Tiebing, and Yuwen Zhang. "Three-Dimensional Modeling of Laser Sintering of a Two-Component Metal Powder Layer on Top of Sintered Layers." Journal of Manufacturing Science and Engineering 129, no. 3 (December 18, 2006): 575–82. http://dx.doi.org/10.1115/1.2716714.

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A three-dimensional model of selective laser sintering of a two-component loose metal powder layer on top of previously sintered layers by a single-line laser scanning is presented. A temperature-transforming model is employed to model melting and resolidification accompanied by partial shrinkage during laser sintering. The heat losses at the top surface due to natural convection and radiation are taken into account. The liquid flow of the molten low-melting-point metal powders, which is driven by capillary and gravity forces, is also considered and formulated by using Darcy’s law. The effects of the dominant processing parameters, such as laser-beam intensity, scanning velocity, and number of the existing sintered layers underneath, are investigated.

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Bibas, Charles. "Lens-Free Optical Scanners for Metal Additive Manufacturing." JOM 74, no. 3 (February 14, 2022): 1176–87. http://dx.doi.org/10.1007/s11837-021-05044-8.

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AbstractGalvanometer scanners (GSs) driving selective laser sintering (SLS)/selective laser melting (SLM) printers for additive manufacturing (AM) have mechanical limits. They provide inconsistent energy density across the print surface because of changes in optical path length, surface beam speed, and angle of incidence. The resulting thermal gradients may be particularly problematic for metal, whose high heat conductivity makes temperature prediction during printing critical. In this paper, we mathematically analyze and compare GSs with a new lens-free optical scanner. The results show that the latter can facilitate metal printing by providing consistent energy deposition across the print surface.

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Edith Wiria, Florencia, Kah Fai Leong, and Chee Kai Chua. "Modeling of powder particle heat transfer process in selective laser sintering for fabricating tissue engineering scaffolds." Rapid Prototyping Journal 16, no. 6 (October 5, 2010): 400–410. http://dx.doi.org/10.1108/13552541011083317.

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Ploszajski, Anna R., Richard Jackson, Mark Ransley, and Mark Miodownik. "4D Printing of Magnetically Functionalized Chainmail for Exoskeletal Biomedical Applications." MRS Advances 4, no. 23 (2019): 1361–66. http://dx.doi.org/10.1557/adv.2019.154.

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AbstractChainmail fabrics manufactured by selective laser sintering 3D printing have been magnetically functionalized to create a lightweight, 4D printed, actuating fabric. The post-processing method involves submerging the porous prints in commercial ferrofluid (oil-based magnetic liquid), followed by drying under heat. The actuation of the chainmail has been simulated using a rigid multi-body physics engine, and qualitatively matches experiment. Such magnetically actuating fabrics have potential to make thin, lightweight and comfortable wearable assistive devices.

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Canfield, Nathan L., Jarrod V. Crum, Josef Matyas, A. Bandyopadhyay, K. Scott Weil, Larry R. Pederson, and John S. Hardy. "Sintering of Mixed-Conducting Composites for Hydrogen Membranes from Nanoscale Co-Synthesized Powders." Materials Science Forum 539-543 (March 2007): 1415–20. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1415.

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The potential for highly selective, nongalvanic permeation of hydrogen through dense mixed conducting composites at elevated temperatures makes them attractive as hydrogen separation membranes. The glycine-nitrate combustion synthesis technique has been used to co-synthesize a cation-doped barium cerate protonic conducting phase together with a metallic nickel electronic conducting phase (15-35 vol% Ni). Co-synthesis of these phases results in an intimately mixed powder with particle sizes on the order of 10 nm. DTA/TGA of all as-synthesized compositions determined that a calcination temperature of 1000°C was required for full reaction of the cerate components. DTA/TGA and sintering shrinkage dilatometry were performed on calcined powders to determine that a sintering temperature of 1250°C would be adequate for achieving >90% relative density in all compositions. Bars of the material containing 25 vol% Ni were reduced at three different points in the heat treatment process (e.g., before, during, or after sintering). It was determined that there was less porosity in the sample reduced during sintering than any other. It was also seen on SEM that the primary grain size, regardless of when reduction occurred compared to sintering of the material, is less than 5 8m.

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Esarte, Jesús, Jesús M. Blanco, Angela Bernardini, and Ramón Sancibrián. "Performance Assessment of a Three-Dimensional Printed Porous Media Produced by Selective Laser Melting Technology for the Optimization of Loop Heat Pipe Wicks." Applied Sciences 9, no. 14 (July 19, 2019): 2905. http://dx.doi.org/10.3390/app9142905.

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The primary wick in a loop heat pipe device is a key component that is central to the operation of the device. Both high permeability and capillary pumping capacity, two properties highly dependent on wick structure, are strongly desirable for a satisfactory thermal performance. In this paper, selective laser melting (SLM), a three-dimensional (3D) printing technology, is used to create a primary wick for an 80 W heat transfer application. The permeability and capillarity values of this wick, experimentally measured, are compared with those built with the most widely used technologies nowadays, such as powder sintering and meshes. In this study, the SLM scaffold is shown to satisfy the minimum values required by the application in terms of capillarity and permeability: 0.031 mm/s and 4 × 10−12 m2, respectively. Our comparative study revealed that the wick produced with the SLM technology presented higher values of permeability, by two orders of magnitude, and slightly higher capillary figures than those corresponding to powder sintering for such application. However, it had capillary values well below those of a stainless-steel mesh. The hydraulic behavior of the SLM wick was better than that of the sintered copper powder, because it not only met the above-mentioned specifications, but it also improved its performance.

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Pugachuk, A. S., N. F. Fominykh, E. O. Kalashnikova, and Yu A. Gavrilova. "Investigating the hydraulic resistance in the flow part elements of pneumatic systems and heat exchangers." Journal of Physics: Conference Series 2057, no. 1 (October 1, 2021): 012015. http://dx.doi.org/10.1088/1742-6596/2057/1/012015.

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Abstract The article deals with the development of shell-and-tube heat exchangers for the needs of power engineering, based on additive technologies, in particular, selective laser sintering technology with new configurations of heat exchange surfaces. The role of heat exchangers in microturbines, the most common units of power plants of small distributed power generation, is considered. To intensify heat transfer and increase the efficiency of microturbines, it is proposed to use various configurations of flow channels of shell-and-tube heat exchangers made on the basis of additive technologies. Mathematical modeling and experimental study of a gas medium flow in the tubes of a heat exchanger are carried out. The dependences of the coefficient of hydraulic resistance between the surface of inlet and outlet of gas from tubes of various configurations on the Reynolds number are obtained. The results of the experiment allow us to conclude that the resistance of spiral-shaped tubes is slightly higher than the resistance of tubes with three ribs.

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Aravind, A., T. N. Siddiqui, P. Arunkumar, and E. Balasubramanian. "Comparative Study of High Performance Polymers in Selective Inhibition Sintering Process through Finite Element Analysis." Polymers and Polymer Composites 25, no. 3 (March 2017): 199–202. http://dx.doi.org/10.1177/096739111702500303.

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Selective Inhibition Sintering (SIS) is a novel additive manufacturing process which uses indigenously available polymers and the high cost laser system is avoided that makes the system cost-effective. Finite Element Analysis (FEA) is carried out to evaluate the performance of SIS process. The effect of temperature on the polymer structure is examined through coupled field transient thermo-structural analysis of various high performance polymer particles such as Polysulfone (PSU), Polybenzimidazole (PBI), Polyimide (PI), Polyethersulfone (PES), Perfluoroalkoxy alkanes (PFA), Ethylene tetrafluoroethylene (ETFE) and KCl is used as the inhibitor material. The structured finite element mesh model is created and heat flux is applied in equivalent time intervals to study the transient characteristics. Simulation results are presented with displacement, temperature and thermal stress for each polymer materials and their characteristics performance is evaluated.

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Asiabanpour, Bahram, Chandrashekar Subbareddy, Sravan Kolichala, and Lane VanWagner. "The heat element status assignment algorithms for the selective inhibition of sintering process array-based heating system." International Journal of Computer Applications in Technology 32, no. 2 (2008): 104. http://dx.doi.org/10.1504/ijcat.2008.020335.

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Brajlih, Tomaz, Urska Kostevsek, and Igor Drstvensek. "Influence of part’s geometrical properties on shrinkage and laser heat affected zone size at selective laser sintering." Rapid Prototyping Journal 25, no. 1 (January 7, 2019): 208–20. http://dx.doi.org/10.1108/rpj-01-2018-0032.

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Purpose One of the main problems of selective laser sintering (SLS) manufacturing process is the dimensional accuracy of products. Main causes of dimensional deviations are material shrinkage and size of laser heat affected zone (LHAZ). This paper aims to present a new method of adapting SLS manufacturing shrinkage and LHAZ compensation parameters to the geometrical characteristics of processed parts to improve their accuracy. Design/methodology/approach The first part of this work presents a hypothesis asserting that the shrinkage and the LHAZ size depend on geometrical properties of products. A method that defines geometrical properties by numerical influence factors is described in the continuation. A multi-factorial experiment with adaptable test part is set up. Then, test builds are manufactured on an SLS machine and measured with a three-dimensional optical scanner. Afterwards, the results are analysed in relation to the presumed hypothesis. Findings The analysis of variance of multi-factorial experiment proves the hypothesis and the influence of the geometrical properties on the accuracy of the SLS manufacturing process. Afterwards, a part is manufactured with adapted values of compensation parameters and the archived accuracy is discussed. Research limitations/implications Presented research is limited on a single SLS material. Also, some numerical factors are directly linked to the build volume dimensions of the SLS machine that was used in the experiment. However, results can be generalised and some guidelines for shrinkage and LHAZ compensation method are presented. Also, some guidelines for future research are proposed. Practical implications Based on the presented results, it can be determined that using constant shrinkage and LHAZ values on an SLS machine will not yield the same results in terms of accuracy if the geometrical properties of parts change significantly. Social implications By correctly adapting compensation values, the overall achievable accuracy of the SLS process can be achieved, enabling a more reliable production of mass-customised end-user parts such as customised medical accessories and devices for example. Originality/value A similar method of numerically describing geometrical properties of part in regard to SLS and directly adapting shrinkage and LHAZ compensation values to them for every individual build has not yet been proposed.

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Kolobov, Yu R., A. N. Prokhorov, S. S. Manokhin, A. Yu Tokmacheva-Kolobova, D. I. Serebryakov, and V. V. Afanasiev. "Comparative study of structural phase condition and mechanical properties of Ni–Cr(X) и Fe–Cr(Х) heat-resistant alloys obtained using additive technologies." Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings), no. 3 (September 16, 2018): 76–86. http://dx.doi.org/10.17073/1997-308x-2018-3-76-86.

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The comparative study covers the features of formation, thermal stability of structure and mechanical properties of heatresistant Ni and Fe based alloys obtained using additive technologies (AT) by direct metal laser sintering, selective laser melting. It is found that alloys obtained by direct metal laser sintering have a cellular structure formed with small pores up to 200 nm in size, in contrast to alloys obtained by selective laser melting having elements with a globular and lamellar morphology and not completely melted areas as well as large pores about 5 μm in size. The study reveals a possible effect of nanophase hardening due to the presence of nanosized particles of chromium silicides in the material. A comparative analysis of the mechanical properties of studied materials is carried out. It is shown that the iron-based alloys have higher strength and lower ductility compared to nickel alloys. All studied samples obtained by selective laser melting demonstrate higher strength characteristics in comparison with alloys obtained by laser metal deposition. As a result of short-term annealing at a temperature of 900–1000 °C for 1 h leads to a significant reduction in the plasticity and strength of iron-based AT alloys during tensile and compression tests at room and elevated temperatures. During compression tests at t = 900 °C, iron-and nickel-based alloys obtained by laser metal deposition have similar strength characteristics. Unlike iron-based alloys, additional annealing of nickel-based AT alloys has virtually no impact on its strength properties.

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van Belle, Laurent, and Alban Agazzi. "Inverse Thermal Analysis of Melting Pool in Selective Laser Melting Process." Key Engineering Materials 651-653 (July 2015): 1519–24. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.1519.

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The Selective Laser Melting (SLM) process of metallic powder is an additive technology. It allows the production of complex-shaped parts which are difficult to obtain by conventional methods. The principle is similar to Selective Laser Sintering (SLS) process: it consists, from an initial CAD model, to create the desired part layer by layer. The laser scans a powder bed of 40 μm thick. The irradiated powder is instantly melted and becomes a solid material when the laser moves away. A new layer of powder is left and the laser starts a new cycle of scanning. The sudden and intense phase changing involves high thermal gradients which induce contraction and expansion cycles in the part. These cycles results in irreversible plastic strains. The presence of residual stresses in the manufactured part can damage the mechanical properties, such as the fatigue life. This study focuses on the thermal and mechanical modelling of the SLM process. One of the key points of the mechanical modelling is the determination of the heat source generated by the laser in order to predict residual stresses. This work is divided in three parts. In a first part, an experimental protocol is established in order to measure the temperature variation during the process. In the second part, a thermal model of the process is proposed. Finally, an inverse method to determine the power and the shape of the heat source is developed. Experimental and computational results are fitted. The influence of several geometries of the heat source is investigated.

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Svyetlichnyy, Dmytro, Michal Krzyzanowski, Robert Straka, Lukasz Lach, and W. Mark Rainforth. "Application of cellular automata and Lattice Boltzmann methods for modelling of additive layer manufacturing." International Journal of Numerical Methods for Heat & Fluid Flow 28, no. 1 (January 2, 2018): 31–46. http://dx.doi.org/10.1108/hff-10-2016-0418.

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Purpose The holistic numerical model based on cellular automata (CA) and lattice Boltzmann method (LBM) are being developed as part of an integrated modelling approach applied to study the interaction of different physical mechanisms in laser-assisted additive layer manufacturing (ALM) of orthopaedic implants. Several physical events occurring in sequence or simultaneously are considered in the holistic model. They include a powder bed deposition, laser energy absorption and heating of the powder bed by the moving laser beam, leading to powder melting or sintering, fluid flow in the melted pool and flow through partly or not melted material, and solidification. The purpose of this study is to develop a structure of the holistic numerical model based on CA and LBM applicable for studying the interaction of the different physical mechanisms in ALM of orthopaedic implants. The model supposed to be compatible with the earlier developed CA-based model for the generation of the powder bed. Design/methodology/approach The mentioned physical events are accompanied by heat transfer in solid and liquid phases including interface heat transfer at the boundaries. The sintering/melting model is being developed using LBM as an independent numerical method for hydrodynamic simulations originated from lattice gas cellular automata. It is going to be coupled with the CA-based model of powder bed generation. Findings The entire laser-assisted ALM process has been analysed and divided on several stages considering the relevant physical phenomena. The entire holistic model consisting of four interrelated submodels has currently been developed to a different extent. The submodels include the CA-based model of powder bed generation, the LBM-CA-based model of heat exchange and transfer, the thermal solid-liquid interface model and the mechanical solid-liquid interface model for continuous liquid flow. Practical implications The results obtained can be used to explain the interaction of the different physical mechanisms in ALM, which is an intensively developing field of advanced manufacturing of metal, non-metal and composite structural parts, for instance, in bio-engineering. The proposed holistic model is considered to be a part of the integrated modelling approach being developed as a numerical tool for investigation of the co-operative relationships between multiphysical phenomena occurring in sequence or simultaneously during heating of the powder bed by the moving high energy heat source, leading to selective powder sintering or melting, fluid flow in the melted pool and through partly (or not) melted material, as well as solidification. The model is compatible with the earlier developed CA-based model for the generation of the powder bed, allowing for decrease in the numerical noise. Originality/value The present results are original and new for the study of the complex relationships between multiphysical phenomena occurring during ALM process based on selective laser sintering or melting, including fluid flow and heat transfer, identified as crucial for obtaining the desirable properties.

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Коваль, Никита Олегович, and Оксана Сергеевна Воденникова. "ДОСЛІДЖЕННЯ МЕХАНІЧНИХ ВЛАСТИВОСТЕЙ ТА СТРУКТУРИ СПЛАВУ IN718, ОТРИМАНОГО МЕТОДОМ 3D-ПРИНТИНГУ." Aerospace technic and technology, no. 3 (June 26, 2020): 21–29. http://dx.doi.org/10.32620/aktt.2020.3.03.

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The subject of research – the process of structure formation and improvement of mechanical properties of high-resistant alloys obtained by 3D-printing. The purpose of work – control the level of mechanical properties of high-resistant alloys obtained by 3D-printing for the manufacture of parts of aircraft gas turbine engines. Objectives – experimental determination of mechanical properties of heat-resistant nickel alloy IN718 obtained by selective laser sintering of LPW and Sino Euro powders both in the horizontal XY and in the vertical Z direction; a comparative analysis of the mechanical properties of IN718 and ЭП718-ВД(ИД) (ХН45МВТЮБР) alloys according to ASM 5662M and TU 14-1-3905-85; a study of the structure of samples of IN718 alloy before and after heat treatment. Research methods – when summarizing and analyzing scientific and technical literature in the direction of studying mechanical properties and forming the structure of heat-resistant nickel alloys obtained by the method of selective laser sintering, an integrated approach was used; processing and analysis of experimental data on determining the mechanical properties of the IN718 alloy in the three-dimensional direction (horizontal direction XY and vertical direction Z); metallographic studies of samples of the IN718 alloy made by 3D-printing were carried out before and after heat treatment. The results obtained - by comparing the mechanical properties of the heat-resistant alloy IN718 obtained by 3D printing from powders LPW and Sino Euro with the normative characteristics ASM 5662M (for alloy IN718) and TU 14-1-3905-85 (for alloy ЭП718-ВД) it was found that for vertical samples (grown in the Z direction) a certain decrease in the strength characteristics and an increase in plastic characteristics compared with the values of horizontal samples (grown in the XY direction), and in terms of impact strength, the IN718 alloy exceeds the norm in the researched temperature range 3.75 times. Scientific novelty – the dependence of the structural characteristics and mechanical properties of the IN718 alloy on the direction of part growth has been established and it has been shown that after heat treatment it is possible to obtain a dense, uniform microstructure characterized by a fine-grained structure with micro grains that are elongated in the direction of sample growth.

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Neuberger, Heiko, Joerg Rey, Manuel Hees, Edeltraud Materna-Morris, Daniel Bolich, Jarir Aktaa, Andreas Meier, et al. "Selective Laser Sintering as Manufacturing Process for the Realization of Complex Nuclear Fusion and High Heat Flux Components." Fusion Science and Technology 72, no. 4 (September 12, 2017): 667–72. http://dx.doi.org/10.1080/15361055.2017.1350521.

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Porojan, Liliana, Mihaela Bîrdeanu, Cristina Savencu, and Sorin Porojan. "Characterization of Dental Metal-Ceramic Interfaces of Heat Pressed Ceramics on Co-Cr Frameworks Obtained with Different Technologies." Applied Mechanics and Materials 876 (February 2018): 25–30. http://dx.doi.org/10.4028/www.scientific.net/amm.876.25.

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It is known that the quality of metal-ceramic restorations mainly depends on the interface strength. The aim of the study was to evaluate metal–ceramic interfaces of heat pressed ceramic on Co-Cr frameworks obtained with different technologies: melting-casting (CST), computerized milling (MIL), selective laser sintering (SLS) and selective laser melting (SLM). The microstructure of metal–ceramic interfaces and framework topography were characterized by scanning electron microscope (SEM). Sandblasted, polished surfaces and the cross section on the interfaces were observed. Sandblasted surfaces presented a uniform rough aspect and pronounced porous surface compared to that of polished surfaces and were better visible in SLS and SLM samples. The thickness of the veneer layer had a noticeable effect on the interface, because in the case of thicker veneers, cracks at the interfaces were visible for CST and MIL specimens. Considering the findings reported herein, some suggestions can be considered in practice, such as adaptation of the restorations morphology to the characteristics of the processed materials.

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Pavlenko, A. N., D. V. Kuznetsov, and V. P. Bessmeltsev. "Heat Transfer Enhancement during Pool Boiling of Nitrogen on Porous Coatings Produced by Selective Laser Melting/Sintering (SLM/SLS)." Journal of Engineering Thermophysics 31, no. 1 (March 2022): 1–10. http://dx.doi.org/10.1134/s1810232822010015.

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Yu, Hao, Shigenari Hayashi, Koji Kakehi, and Yen-Ling Kuo. "Study of Formed Oxides in IN718 Alloy during the Fabrication by Selective Laser Melting and Electron Beam Melting." Metals 9, no. 1 (December 24, 2018): 19. http://dx.doi.org/10.3390/met9010019.

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This study confirmed that Al2O3 particles were formed in IN718 alloys during the fabrication by both selective laser melting (SLM) and electron beam melting (EBM). Different heat pattern and atmospheres in SLM and EBM result in different distribution and volume fraction of Al2O3 particles. The Al2O3 oxides would act as nucleation sites for the precipitation of Nb/Ti carbides, leading to the formation of unique core-shell composites with Al2O3 in the center and Ti/Nb at the periphery. In order to investigate the oxygen content introduced during SLM and EBM, the volume fraction of Al2O3 formed in spark plasm sintering (SPS)-fabricated substrate, by consolidating the pre-oxidized IN718 raw powders at 800 °C, was utilized. The oxygen contents introduced to IN718 substrates during SLM and EBM fabrication were calculated to be 0.030 wt% and 0.099 wt%, respectively.

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Nguyen, Minh-Thuyet, Hoang-Viet Nguyen, Thai-Hung Le, Quoc-Khanh Dang, and Jin-Chun Kim. "Properties of the interface between the as-built Ti–6Al–4V sample and the Ti substrate in selective laser sintering." International Journal of Modern Physics B 34, no. 22n24 (August 25, 2020): 2040137. http://dx.doi.org/10.1142/s0217979220401372.

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In this paper, selective laser sintering (SLS) was applied to join two materials by printing Ti–6Al–4V powder on a Ti substrate without any support parts. The characteristics of the interface between the as-built Ti–6Al–4V sample and the substrate were investigated. The analysis indicates that a heat-affected zone (HAZ) and the fish-scale type were formed at the joining area. The combination of smaller grains, acicular [Formula: see text] martensite, and lamellar [Formula: see text] structures was observed inside the interface zone. The hardness value at the interface area was measured by about 320 HV which is higher than 280 HV of the substrate and smaller than 369 HV of the as-built sample. The results predict that the SLS process is a promising method for manufacturing of hybrid materials.

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Wu, Hao, Rogelio Ortiz, and Joseph H. Koo. "Rubber toughened flame retardant (FR) polyamide 11 nanocomposites Part 2: synergy between multi-walled carbon nanotube (MWNT) and MMT nanoclay." Flame Retardancy and Thermal Stability of Materials 2, no. 1 (January 1, 2019): 19–29. http://dx.doi.org/10.1515/flret-2019-0003.

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AbstractIn the previous study, flame retardant (FR) polyamide 11 (PA11) nanocomposites formulations designed for selective laser sintering (SLS)were prepared and characterized. The SEBS-g-MA elastomer successfully improved the material’s ductility. Although the nonhalogenated FR additives and montmorillonite (MMT) nanoclay successfully decreased the heat release capacity (HRC) and peak heat release rate (pHRR) as characterized by microscale combustion calorimeter (MCC). None of the rubber toughened formulations achieved UL 94 V0 rating, which is a bench mark for many FR polymer applications. As part two of this study, we explored the synergism between two nanoparticles, nanoclay and multi-walled carbon nanotubes (MWNTs), to see whether better FR properties can be achieved. TEM micrographs indicate that both nanoclay and MWNTs achieved high level of dispersion. Flammability results showed that all formulations achieved UL 94 V0 rating, which is a significant improvement from the previous formulations without MWNTs. Char morphology characterization indicated that a solid carbonaceous char layer was reinforced by nanoclay and MWNTs.

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Wu, Tao, Yiru Tang, Dongdong Fei, Yongbo Li, and Wangyong He. "Researches on Temperature Control Strategy of SMHS-Type 3D Printing Based on Variable Universe Fuzzy Control." Journal of Advanced Computational Intelligence and Intelligent Informatics 21, no. 1 (January 20, 2017): 166–71. http://dx.doi.org/10.20965/jaciii.2017.p0166.

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Selective micro heat sintering (SMHS)-type 3D printing technology is a widely applied method in rapid prototyping, which uses an electric heating component to sinter non-metallic powder. It requires precise control of the heating component’s energy and its sintering time. Temperature is one of the key factors that affect the forming quality of fused-type 3D printing technology. Aiming at the nonlinear and time-delay characteristics of temperature control in fused-type 3D printing, a fuzzy control method based on variable universe fuzzy control was studied. This fuzzy control method adopts a set of nonlinear expansion-contraction factors to make the variable universes change with the adaptive error, which can help acquire adaptive temperature adjustment in the rapid prototyping process control. The results of the simulation and experiment showed that the controlled temperature response was faster, the overshoot was smaller, and the stability was better compared to the conventional fuzzy proportion integration differentiation (PID) algorithm after the temperature reached the target temperature. The printed results indicated that the universe fuzzy PID control can effectively improve the accuracy of the workpiece shapes and that the density distribution of the workpiece is increased, which can help improve the forming quality.

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Journal articles on the topic 'Selective heat sintering'

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