Papers by Keyword: Thermal Analysis

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Authors: Xi Ping Li, Guo Qun Zhao, Yan Jin Guan
Abstract: Rapid electrical heating cycle injection molding technology can be used to produce polymer parts with no weld mark, flow mark and other surface defects on the parts surface. Recently, it has been gradually found wide use in plastic injection industry. In this paper, a structure of the rapid electrical heating cycle injection mold and its working processes were presented. As the production efficiency and the part’s quality are seriously affected by the temperature of the mold cavity surface and its distribution uniformity, the heat transfer process of the mold was analyzed by using 3D finite element simulation. The transient temperature values on different places of the cavity surface were obtained. The results provided theoretical guidelines for the engineers to evaluate the layout of the heating rods in the mold.
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Authors: Zaliman Sauli, Vithyacharan Retnasamy, Fairul Afzal Ahmad Fuad, Phaklen Ehkan, Rajendaran Vairavan, Nazuhusna Khalid
Abstract: Conventional incandescent lamps are being replaced by high power light emitting diode as a lighting source due to it ascendancy in terms of physical size, performance, output and lifetime. Nevertheless, the reliability and efficiency of the LED is dependent on the junction temperature. This study presents the thermal simulation of single chip LED package with 5mm x5mmx 1mm aluminum heat slug. The junction temperature and stress of LED chip were evaluated using Ansys version 11. Input power of 0.1 W and 1 W were applied to the LED. The simulation results showed that at input power of 1W, the maximum junction temperature and stress of the LED chip is 112.91°C and 263.82Mpa respectively.
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Authors: Pieter Samyn, Alessandro Ledda, Jan Quintelier, Isabel Van Driessche, Gustaaf Schoukens, Patrick de Baets, Wim De Waele
Abstract: Polymer wear debris particles undergo a thermal and mechanical (shear) cycle since their generation and therefore contain information on the friction and wear processes, while it is often difficult to draw quantitative data from them relating to transitions in tribological behaviour. Results from thermal DTA/TGA analysis and morphological pattern spectra of debris are presented and related to a transition at 180°C sliding temperatures own to hydrolysis and imidisation.
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Authors: Min Jiang, Cheng Gao, Jiao Ying Huang, Gui Cui Fu, Ying Cheng
Abstract: This paper introduces a new method to obtain the copper coverage of PCB. Board-level simulation is very important in the thermal analysis and reliability design of electronic equipment. While in the process of PCB modeling, it is difficult to obtain the coverage percentage of copper in the PCB layer. By this method, the calculation of the coverage is converted to MATLAB image processing problems, is more simple than the traditional methods and the precision is higher, with strong practical.
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Authors: Lei Liu, Wei Hong Wu, Huan Huan Xue, Hong Qiang Qu
Abstract: A series of metal molybdates were synthesized as flame-retardants and smoke suppressants for flexible poly (vinyl chloride). The powder of molybdates was characterized by the x-ray diffraction. The flame retardancy, smoke suppression and thermal behavior of PVC treated with a series of molybdates were studied by means of limiting oxygen index (LOI), smoke density rating (SDR), thermogravimetry (TG), differential thermogravimetry (DTG), differential thermal analysis (DTA) and scanning electron microscopy (SEM). The results shown that, the flame retardancy and smoke suppression performance of PVC samples depend on the strength of the Lewis acid which generated in the first degradation stage and the stability of residue char in the second stage. While the strong Lewis acid can also function as cracking catalysts in the second stage, and cracking of the principally hydrocarbon char can promote the generation of volatile organic compounds, which act as efficient fuels. This situation results in less smoke, but increased flame.
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Authors: Vasilios Fourlakidis
Abstract: This paper investigates the effects of graphite added as a conditioner, of Lantanum containing nodulariser and of pouring temperature on the formation of shrinkage porosity in ductile iron casting with an eutectic composition. In this experiment for each heat the cooling curves were recorded by the use of Quick-Cups (thermal analysis cups) and different solidification parameters such as TElow, GRF1, GRF2 and TS were calculated and compared with the porosity which was found from the microstructure examination. The results show that there is a good correlation between the amount of the shrinkage formation and the thermal analysis values. Also this experiment confirm that by using certain treating elements and pouring temperature which was between 1340-1350°C it is possible to eliminate the shrinkage defects in ductile iron castings without using feeders.
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Authors: Aurel Raduta, Mircea Nicoară, Cosmin Locovei
Abstract: A research program has been completed in order to analyze structural changes during heating of amorphous alloys belonging to Fe-Ni-P system. Special attention has been given to thermodynamics and mechanism of crystallization, to determine some aspects of development for crystalline phases. Experimental material used to determine characteristics of crystallization consisted in long ribbons, 30 thick and 18 mm wide, fabricated by mean of “Planar Flow casting” as amorphous Fe42Ni38P16B4 alloy. Differential Thermal Analysis (DTA) and X-rays diffraction have been used to determine crystallization temperature of this alloy. Curves of differential thermal analysis for heating rates ranging between 1°C/minute and 20 °C/minute have been used to determine activation energy of crystallization.
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Authors: Robert Mackay, Ron Hausenbusch, Jerry Sokolowski
Abstract: The main aim of the metallurgical investigation was to enhance our understanding of the role Cu and Si have on the development of shrinkage porosity in the as-cast structure, which in turn can affect high cycle fatigue (HCF) properties of Al-9Si-1Cu (W328) and Al- 7Si-4Cu (W319) alloys. In order to achieve this objective a novel approach using thermal analysis and calculated fraction solid techniques was developed to assess mushy zone kinetics, the state between the liquidus and solidus where a solid skeletal α-Al phase and the Al-Si eutectic phase grow at the expense of an inter-dendritic liquid. Specifically, the cooling curve and calculated fraction solid curve were partitioned into segments, which reflect different stages of feeding through the entire solidification event of the alloy. Each partitioned segment corresponds to a stage of feeding, which in turn signifies a relative degree of pore growth susceptibility. Two thermal analysis techniques, both using calibrated thermocouples, were used to precisely understand the solidification path for both the W319 alloy and the W328 alloy.
392
Authors: Nur Azmah Nordin, Saeed Farahany, T. Abubakar, Esah Hamzah
Abstract: Owing to its beneficial material properties, Al-Mg2Si in-situ composite has recently received wide attention and application in the manufacture of automotive and aerospace components. Melt treatment of the in-situ composite with the addition of Ce has resulted in a change in the primary and eutectic Mg2Si phases to refined morphology, which would be expected to improve the mechanical properties of the composite. Characteristic parameters of Mg2Si particles have been investigated via thermal and microstructural analysis. This has revealed that the addition of 0.8wt.% Ce produced optimum refinement effects on Mg2SiP because the coarse structure has been changed to a polygonal shape and reduced in size. Similarly, the flake-like morphology of Mg2SiE has been transformed into a rod-like or fibre form in addition to reduction of the eutectic cell area. The result also showed an increase in nucleation temperature TN of Mg2SiP while depressed for Mg2SiE, which also corresponds to the refinement morphology effect.
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Authors: Marin Gostimirović, Vladimir Pucovsky, Pavel Kovač, Milenko Sekulić, Borislav Savković
Abstract: This paper indicates the occurrence of high thermal energy in the surface layer of workpiece material during the process of grinding. To help identify the share of heat which affects the workpiece, firstly the analysis of past research in the field of heat transfer during grinding was conducted. Further there is a proposition of analytical expression for heat distribution factor to the workpiece in the grinding process. Goal of this analytical dependence is to achieve more efficient production of mechanical parts without thermal defects in the surface layer of the part. Presented equation for energy partition has a characteristic of widespread practical use.
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