Thermal Deformation Characteristics Research Articles

Multiphysics-based simulation on heat conduction mechanism of TFC head and its influencing factors

In order to precisely control the flying height of TFC head with consideration of microscale thermal effect, the thermal conducting characteristics and the influencing factors on TFC slider which is in an operation and multi-physics field condition were analyzed. In consideration of rarefaction effect of ultra-thin film at the head/disk interface, the models of slider heat conduction, air bearing surface heat transfer, and gas flow were established; the thermal deformation mechanism and the effect of thermal conduction on dynamic characteristics of slider were analyzed by using finite element method. Results show that the thermal conducting model and the proposed modification of Reynolds equation in this study are suitable for solving the problems of thermal deformation and dynamic characteristics of head slider. The main parameters that influence the thermal property of slider can be considered to be the heater height, heat generation rate, and the heat conductivity coefficient of the material. The change of the slider flying height is determined by the air bearing force and the air bearing surface thermal extrusion at the head/disk interface. Simulation results provide a basis for the design of heater in head slider and analysis of dynamic characteristics of air bearing.

G0310103 シリコンの厚さを考慮したソーラーセルタブ部の熱変形解析(材料力学部門一般セッション:変形・ひずみ(1))

Transformation of conventional energy systems to renewable energy can limit the climate change to a safe level. Among the sources of renewable energy, solar energy is more convenient and easy to access. However, high cost of silicon wafer is a problem for photovoltaic solar cells. Therefore, manufacturers need to the development of solar cells made of thinner crystalline silicon wafer as a way to reduce costs. Silicon is brittle, and thinner silicon is easier to break due to residual stress induced during soldering process under high temperature. The solar cell conductive film (CF) can bonds the solar cell with metal ribbon at lower temperature than soldering. After the manufacturing process when the solar panel is subsequently exposed to sunlight for its operation, the temperature distribution redistributes the residual stress. Therefore, it is necessary to know how silicon wafers of different thicknesses are deformed for the two bonding materials, solder and CF in order to find out a reliable bonding option for thinner silicon. This study used the finite element method (FEM) to analyze the thermal deformation during the manufacturing and using processes of solar cells with different thicknesses of silicon wafer. It was found that varying the thickness of silicon wafer has long term effects on the deformation and residual stress. Sn-3.5Ag solder and CF were employed as the bonding interface to carry out a comparison of the thermal deformation characteristics.

Heat Transfer and Thermal Deformation Characteristics of Liquid-Cooled Laser Mirror

A coupled finite volume-element method is developed to simulate the transient thermal deformation of water-cooled mirror by considering fluid flow and convective heat transfer. The simulation process consists of two steps: the 3D finite volume models of fluid flow and heat transfer equation are solved to obtain the time-dependent temperature field by using CFD; then, the obtained temperature field used as final temperature field is unidirectionally coupled to the finite element model for solving the thermoplastic equation. It is concluded that fluid flow not only affects the magnitude of temperature rise and thermal deformation, but also affects the distribution of temperature and thermal deformation. The temperature gradient in the thickness direction ( z direction) is found to be much larger than that in transverse direction. It is found that the temperature and the consequent deformation of water-cooled mirror increase significantly in the first seconds and gradually become steady state in the subsequent time. Experiments are conducted to estimate the precision of numerical models, and the experimental results agree well with the simulated results.

멤브레인 LNG 선박용 강화 폴리우레탄폼의 극저온 거동 연구

In the context of the structural performance of an LNG hold, the mechanical characteristics of the insulation material are considered to be a critical design factor under cryogenic temperatures. This paper presents the thermal elasto-plastic behavior of the reinforced polyurethane foam (RPUF) adapted for the insulation material of a membrane-type LNG carrier via both experiments and numerical simulations realizing the cryogenic condition. The experiments are carried out to investigate the thermal transfer and thermal elasto-plastic deformation characteristics of an actual RPUF specimen. The heat transfer simulations based on the finite element method (FEM) include a forced convection analysis. The results of heat transfer analyses are compared with the experimental results. Reasonable cryogenic conditions for RPUF are reviewed based on both the analysis and experimental results

Structural-Mechanical Control of Bypass Reactivity in LISB for Space Application Using Alloys with Shape Memory Alloys

Keywords: Lithium-ion storage battery (LISB), bypass device, shape memory effect (SME) thermal treatment, reactivity, reliability Abstract. Deformation and strength characteristics of a thermal drive spring made of alloy with shape memory effect (SME) оn the base of TiNi in bypass device (BD) of Lithium-ion storage battery (LISB) for space application were investigated. A technique was developed for this spring thermal preparation for a certain magnitude of shape memory deformation, due to which during reverse martensite transformation a spring generates reactive force, sufficient for BD operation. It allowed to develop small-sized multiple action BDs for LISBs intended for “Glonass-K” spacecrafts. Study of technological and operational factors’ impact proved high level of BD failure-free operation.

IMC의 영향에 따른 Flip-Chip Bump Layer의 열변형 해석

최근 전자 제품의 소형화, 박형화 및 집적화에 따라 칩과 기판을 연결하는 범프의 미세화가 요구되고 있다. 그러나 범프의 미세화는 직경 감소와 UBM의 단면적 감소로 인하여 전류 밀도를 증가시켜 전기적 단락을 야기할 수 있다. 특히 범프에서 형성되는 금속간화합물과 KV의 형성은 전기적 및 기계적 특성에 큰 영향을 줄 수 있다. 따라서 본 논문에서는 유한요소해석을 이용하여 플립칩 범프의 열변형을 분석하였다. 우선 TCT의 온도조건을 통하여 플립칩 패키지의 열변형 특성을 분석한 결과, 범프의 열 변형이 시스템의 구동에 큰 영향을 미칠 수 있음을 확인하였다. 그리고 범프의 열변형 특성에 큰 영향을 미칠 것을 생각되는 IMC층의 두께와 범프의 직경을 변수로 선정하여 온도변화, 열응력 및 열변형에 대한 해석을 수행하였으며, 이를 통하여 IMC층이 범프에 영향을 미치는 원인에 대한 분석을 수행하였다. Recently, by the trends of electronic package to be smaller, thinner and more integrative, fine bump is required. but It can result in the electrical short by reduced cross-section of UBM and diameter of bump. Especially, the formation of IMCs and KV can have a significant affects about electrical and mechanical properties. In this paper, we analyzed the thermal deformation of flip-chip bump by using FEM. Through Thermal Cycling Test (TCT) of flip-chip package, We analyzed the properties of the thermal deformation. and We confirmed that the thermal deformation of the bump can have a significant impact on the driving system. So we selected IMCs thickness and bump diameter as variable which is expected to have implications for characteristics of thermal deformation. and we performed analysis of temperature, thermal stress and thermal deformation. Then we investigated the cause of the IMC's effects.

Effect of post-weld-annealing on the tensile deformation characteristics of laser-welded NiTi thin foil

Laser welding is an important process for fabricating complex components involving NiTi shape memory alloy. As welding is a thermal process, the amount of heat input and the rate of cooling have significant impact on the microstructure and hence the resultant characteristics of NiTi. In this study, the effect of laser welding and post-weld-annealing from 573 K to 1173 K on the thermal phase transformation behaviors, tensile deformation and micro-hardness characteristics of the laser-welded NiTi thin foils were investigated. It was found that the as-welded sample exhibited inferior super-elasticity compared to the base material, and the super-elasticity could be partially restored by annealing at 573 K. On the other hand, annealing of the weldment above the recrystallization temperature would lower the super-elasticity.

Thermal Deformation in a Dry Gas Seal

In order to know thoroughly the thermal deformation characteristics of the dry gas seal in the synthesis gas compressor, the physical model and the thermal equilibrium model of the seal pair are established on its structural and thermal analysis. Based on finite element analysis software ANSYS, separation method are applied to resolve and analyze the temperature field and thermal-structural coupling deformation of the seal pair. The analyzed results show that the temperature of the rotating ring decreases gradually from the end face to the back face, and decreases gradually from the inner radius to the outer radius. The maximum of the temperature gradient of the rotating ring locates at the outer radius of the end face.The deformation of the stationary ring is negative conicity, the deformation of the rotating ring is positive conicity, and the later is the major reason of seal failure. Because of the thermal deformation, the end faces will form a convergent wedge. The convergent wedge favors the formation of a gaseous film, but it will lead to a increase in leakage quantity.

Modeling and Estimating Thermal Error in Precision Machine Spindles

Thermal induced errors are significant factors that affect machine tool accuracy. The deformation of spindle is the main contributor to thermal error. In this paper, the thermal characteristics of the spindle system are investigated. Taking into account the coupling of elastic deformation and temperature, the heat conduction of the spindle system is modeled. The heat of bearings and heat transfer coefficient, and boundary conditions of the spindle are determined. Based on the numerical results, an iterative model of spindle's temperature and thermal deformation are acquired under the actions of thermal loads using the finite element method. Taking the spindle of precision boring machine with some reasonable assumptions and simplicities as an example, the finite element analysis model of spindle thermal characteristics is analyzed with virtual prototyping, and the static/transient temperature field and thermal-structure field are calculated using ABAQUS software. The characteristics of heat flow and thermal deformation within the spindle are analyzed according to the simulation results. The research results provide a theoretical foundation for reasonable arrangement and optimal design to reduce radial and axial deformation of the spindle head, temperature controlling, and the error compensation to the precision machining tool.

선상가열 변형예측식 자동 산출을 위한 지식기반 방법의 개발

For the last couple of decades many studies have been carried out to find out solutions to improve the effectiveness and productivity of the plate forming process. The practical way for the automation of the plate forming process has not been, however, developed yet. Since the characteristics of heating machines may be different form each other, it is necessary to investigate the thermal deformation characteristics of the heating machine to be used in the automation system. And their characteristics may be updated as new information about thermal deformation by heating is accumulated. In this paper, data base system has been constructed based on the results of experiments and numerical analyses, which will be used in deriving the deformation estimation formula. The computer code which can automatically derive the deformation estimation formula has been also developed. This paper also illustrates how the formula is updated as experimental data are added. From the present findings, it can be said that the automatic deriving procedure may be important in the automated plate forming system since the heating line information to be generated must be directly influenced by the deformation estimation formula.

Effect of components of cement paste on thermal deformation characteristics

Components of modern cement paste have become more and more complex. A large amount of unhydrated mineral admixture particles, unhydrated cement particles and entrained air play different roles in the thermal deformation of cement paste. To investigate the effects of these components, a dilatometer was adopted to measure the coefficient of thermal expansion (CTE) of hardened cement pastes (HCP) with different water content, water/cement (w/c) ratio and air content values. The effects of cement, fly ash, slag, calcium silicate hydrate (CSH) gel and calcium hydroxide (Ca(OH)2) particles on CTE were also studied after their surfaces had been treated with silicone to prevent reaction with water. The results showed that the CTE of HCP with different components could be listed in descending sequence as calcium hydroxide, fly ash, cement, slag and CSH; the moisture in HCP increased the CTE, while the air entrained decreased it; the increase of the w/c ratio and porosity reduced the CTE, but the longer moisture curing age made it higher.

관측위성의 MTF 해석을 위한 기본 모델링 기법 연구

본 논문에서는 관측위성의 영상성능을 예측하고 해석하기 위하여 영상 성능의 주요 인자인 전체 시스템의 MTF를 산출하기 위한 시스템 MTF 구조도를 제안하였다. MTF 구조도의 각 요소에 해당하는 기본 모델은 우주 환경에서 광-구조, 열 변형, 자세 및 동역학 특성과 MTF간의 수학적인 관계식으로 표현된다. MTF 기본 모델은 중앙차폐가 있는 광학계의 회절한계, 수차, 비촛점, LOS 지터, 선형운동, 검출기 Integration MTF 등으로 구성된다. 가상의 지구관측위성모델에 대해 영상성능 예측모델링 기법을 적용하여 적절한 결과를 얻을 수 있음을 보였다. 각 기본 모델을 바탕으로 관측위성의 전체 영상성능을 해석하고 개념설계 단계에서 영상성능에 영향을 주는 주요한 설계 매개변수를 도출할 수 있다. A modulation transfer function(MTF) tree is established to estimate the overall MTF of an observation satellite and to analyze the image performance. Basic MTF models relevant to each MTF tree component are represented as mathematical relationship between optics-structural dynamics, thermal deformation, attitude and dynamic characteristics of a satellite and the effects due to the space environment. The Basic MTF models consist of diffraction limited MTF with central obscuration, aberration, defocus, line-of-sight(LOS) jitter, linear motion, detector integration, and so forth. Performance estimation is demonstrated for a virtual earth-observation satellite in order to validate the constructed modeling method. The proposed models enable the system engineers to calculate the overall system MTF and to determine the crucial design parameters that affect the image performance in the conceptual design phase of an observation satellite.

1337 SiC/Alアクティブコンポジットの繊維体積率がその熱変形特性に及ぼす影響(J14-8 知的材料・構造システム(8) 形状可変・復元構造,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

1337 SiC/Alアクティブコンポジットの繊維体積率がその熱変形特性に及ぼす影響(J14-8 知的材料・構造システム(8) 形状可変・復元構造,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

Thermal Prehistory, Structure, and Deformation and Strength Characteristics of Composites Based on Polar Polymers

Thermal Prehistory, Structure, and Deformation and Strength Characteristics of Composites Based on Polar Polymers

유한요소법을 이용한 SNCM 합금강의 침탄열처리 공정 해석

Heat treatment is a controlled heating and cooling process to improve the physical and/or mechanical properties of metal products without changing their shapes. Today finite element method is widely used to simulate lots of manufacturing processes including heat treatment and surface hardening processes, which aims to reduce the number of time- and cost-consuming experimental tryouts. In this study we tried, using this method, to simulate the full carburizing process that consists of carburizing, diffusing and quenching, and to predict the distribution of carbon contents, phase fraction and hardness, thermal deformation and other mechanical characteristics as the results. In the finite element analysis deformation, heat transfer, phase transformation and diffusion effects are taken into consideration. The carburizing process of a lock gear, a part of the car seat recliner, that is manufactured by the fine blanking process is adopted as the analysis model. The numerical results are discussed and partly compared with experimental data. And a combination of process parameters that is expected to give the highest surface hardness is proposed on the basis of this discussion.

Simulation of thermal behavior of a CNC machine tool spindle

The thermal deformations of a CNC machine tool spindle are the major contributor of thermal error. It is very significant both theoretically and practically to study how to accurately simulate the thermal error of the spindle. Firstly, this paper proposes a method for computing the coefficient of convection heat transfer of the spindle surface by referencing the theory on computing the coefficient of convection heat transfer of a flat plate when air flows along it. Secondly, the temperature field and thermal errors of the spindle are dynamically simulated under the actions of thermal loads using the finite element method. Thirdly, the characteristics of heat flow and thermal deformation within the spindle are analyzed according to the simulation results. Fourthly, the selection principle of thermal key points, which are indispensable for building a robust thermal error model, is provided based on the thermal error sensitivity technology. At last, a verification experiment is implemented on a CNC turning center, and the results show the simulation results are satisfying to replace the experiment results for further studies.

Development of active materials based on fiber-reinforced metals

The present paper describes development of active fiber-reinforced metals utilizing their thermal deformation caused by non-uniform distribution or combination of continuous and discontinuous fibers. These types of SiC/Al composites, that is, a laminate of continuous-fiber layer and unreinforced one, that of discontinuous-flber layer and unreinforced one, and that of continuous-fiber layer and discontinuous-flber one were fabricated, and their thermal deformation characteristics were investigated. As the results, all of the composites curve unidirectionally in the flber direction by cooling from the hot pressing temperature. Though the curvature of the composite reinforced on one side decreases by reducing the fiber length, the curvature change during thermal cycles between room temperature and 813 K can be clearly observed even in the case of the discontinuous flber type. The tensile strength of the composite reinforced with continuous flber on one side successfully increases by lamination of the continuous-fiber layer and the discontinuous one. The curvature of this type of active composite can also reproducibly change during the thermal cycles due to the difference of the fiber lengths, and exists between the continuous-flber type and the discontinuous-fiber type ones.

Development of a New Active Material Based on SiC-Fiber/Aluminum Composite

The present paper proposes an active SiC-fiber/aluminum composite utilizing its thermal deformation caused by non-uniform distribution of reinforcement fibers. A laminate of a continuous and unidirectional SiC fiber reinforced aluminum plate and an unreinforced aluminum plate was fabricated by the interphase forming/bonding method using a copper insert foil and its thermal deformation characteristics were investigated. The fabricated composite curved unidirectionally in the fiber direction by cooling from the hot pressing temperature, which is different from the behavior of a bimetal. Curvature of the composite at room temperature was maximized by investigating the effect of thickness of the aluminum plate, distance between the fibers and length of the composite in the experimented range. Under the optimum condition, its dependence on fiber length was clarified. It was also revealed that copper diffused but concentrated around the fibers, and that the interphase forming/bonding method with a copper insert increased the curvature of the composite. In a thermal cycling test, the curvature of the composite at room temperature reduced by heating from that to zero at the temperature of about 580 K. The zero-curvature temperature and the curvature at room temperature were reproducible for ten thermal cycles. These results suggest an availability of this composite as an active material.

Thermal behavior of a machine tool equipped with linear motors

Development of a feed drive system with high speed and accuracy has been a major issue in the machine tool industry. Linear motors can be used as efficient tool to achieve the high speed and accuracy. However, a high speed feed drive system with linear motors, in turn, can generate heat problems. Also, frictional heat is produced at the ball or roller bearing of LM block when driven at high speed. It can affect the thermal deformation of the linear scale as well as that of the machine tool structure. In this paper, important heat sources and resulting thermal errors in a machine tool equipped with linear motors were investigated when it was operated at high speed. The thermal deformation characteristics were identified through measuring the thermal error caused from thermal deformation of the linear scale and the machine tool structure. The dominant thermal error components were identified from the thermal error analysis using finite element method. It was shown that the proposed analysis scheme is efficient in identifying the dominant thermal error components and its magnitudes such as the thermal expansion and movement of the linear scale, thermal deformation of the machine tool slide.

Determination of Stress-Strain Curve for Microelectronic Solder Joint by ESPI Measurement and FE Analysis

Many thermomechanical reliability studies on microelectronics and microsystems have relied upon computational analysis, since experimental work is rather difficult and very time-consuming. For computational analysis, it is essential to use as input accurate material properties; if not, the results of a reliability analysis may be very inaccurate. However, it is still quite difficult to arrive at unified material properties for modeling microelectronic assemblies because of the absence of standards for micro-material characterization, the difference between bulk and in-situ material properties, and so forth. The goal of this study was to determine the uniaxial stress-strain curve of a solder in a flip-chip assembly, using experimental measurements and finite-element analysis (FEA) of the solder's thermal deformation characteristics with increasing temperature. The thermal deformation of flip-chip solder joints was measured by electronic speckle pattern interferometry (ESPI). For the scale of evaluation required, the measurement magnification was modified to allow its application to micromaterials by using a long-working-distance microscope, iris and zoom lens. Local deformation of solder balls could be measured at submicrometer scale, and stress-strain curves could be determined using the measured thermal deformation as input data for finite-element analysis. The procedure was applied to an Sn-36Pb-2Ag flip-chip solder joint.