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Svotina, Victoria V., Andrey I. Mogulkin i Alexandra Y. Kupreeva. "Ion Source—Thermal and Thermomechanical Simulation". Aerospace 8, nr 7 (14.07.2021): 189. http://dx.doi.org/10.3390/aerospace8070189.
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The main purpose of this work is to conduct ground development testing of the ion source intended for use the space debris contactless transportation system. In order to substantiate the operating capability of the developed ion source, its thermal and thermomechanical simulation was carried out. The ion source thermal model should verify the ion source operating capability under thermal loading conditions, and demonstrate the conditions for ion source interfacing with the systems of the service spacecraft with the ion source installed as a payload. The mechanical and mathematical simulation for deformation of the ion source ion-extraction system profiled electrodes under thermal loading in conjunction with the prediction of the strained state based on the numerical simulation of the ion source ion-extraction system units, making it possible to ensure the stability of the ion source performance. Good agreement between the thermal and thermo-mechanical ion source simulation results and experimental data has been demonstrated. It is shown that the developed ion source will be functional in outer space and can be used as an element of the space debris contactless transportation system into graveyard orbits.
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ZHANG, JINAO, JEREMY HILLS, YONGMIN ZHONG, BIJAN SHIRINZADEH, JULIAN SMITH i CHENGFAN GU. "TEMPERATURE-DEPENDENT THERMOMECHANICAL MODELING OF SOFT TISSUE DEFORMATION". Journal of Mechanics in Medicine and Biology 18, nr 08 (grudzień 2018): 1840021. http://dx.doi.org/10.1142/s0219519418400213.
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Modeling of thermomechanical behavior of soft tissues is vitally important for the development of surgical simulation of hyperthermia procedures. Currently, most literature considers only temperature-independent thermal parameters, such as the temperature-independent tissue specific heat capacity, thermal conductivity and stress–strain relationships for soft tissue thermomechanical modeling; however, these thermal parameters vary with temperatures as shown in the literature. This paper investigates the effect of temperature-dependent thermal parameters for soft tissue thermomechanical modeling. It establishes formulations for specific heat capacity, thermal conductivity and stress–strain relationships of soft tissues, all of which are temperature-dependent parameters. Simulations and comparison analyses are conducted, showing a different thermal-induced stress distribution of lower magnitudes when considering temperature-dependent thermal parameters of soft tissues.
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Hrevtsev, O., N. Selivanova, P. Popovych, L. Poberezhny, V. Sakhno, O. Shevchuk, L. Poberezhna, I. Murovanyi, A. Hrytsanchuk i O. Romanyshyn. "Simulation of thermomechanical processes in disc brakes of wheeled vehicles". Journal of Achievements in Materials and Manufacturing Engineering 1, nr 104 (1.01.2021): 11–20. http://dx.doi.org/10.5604/01.3001.0014.8482.
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Purpose: Ensuring the required operational reliability of disc brakes by forecasting their technical condition taking into account thermomechanical processes. Design/methodology/approach: Differential equations of rotation of a rigid body around a fixed axis are solved, it is established that the equations of motion and the equations of thermal conductivity are indirectly related. The use of these analytical dependences provides a better understanding of thermomechanical transients. Findings: The solution is obtained on the basis of the differential equation of thermal conductivity of the hyperbolic type, which does not allow an infinite velocity of propagation of temperature perturbations in contrast to the differential equation of thermal conductivity of the parabolic Fourier type. The obtained analytical dependences provide a better understanding of thermomechanical transients and develop a theoretical basis for determining stresses and heat fluxes in solving problems of reliability and durability of disc brakes. Research limitations/implications: The work uses generally accepted assumptions and limitations for thermomechanical calculations. Practical implications: It is shown, that transients in a mechanical system - a brake disk at impulse loadings cause emergence of thermal effects which arise under the influence of external loadings. Originality/value: The application of these analytical dependences provides a better understanding of thermomechanical transients and develops a theoretical basis for solving problems of reliability and durability of disc brakes.
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Yamashita, Hiroki, Rohit Arora, Hiroyuki Kanazawa i Hiroyuki Sugiyama. "Reduced-order thermomechanical modeling of multibody systems using floating frame of reference formulation". Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 233, nr 3 (15.11.2018): 617–30. http://dx.doi.org/10.1177/1464419318810886.
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In this study, a reduced-order thermomechanical coupling model, which accounts for the inertia coupling of the thermoelastic deformation and the large reference body motion, is proposed using the floating frame of reference formulation for the transient thermomechanical analysis of constrained multibody systems. In this approach, the reduced-order heat equations are fully embedded in the final form of the equations of motion. Accordingly, the transient thermal response as well as the resulting thermoelastic behavior of constrained multibody system can be predicted within the general multibody dynamics computer algorithm. It is demonstrated that appropriate selection of the thermal interface coordinates is crucial for describing the thermal modes (i.e. temperature distribution) induced by external heat sources using the Craig–Bampton component mode synthesis approach generalized for thermomechanical systems. Furthermore, a systematic procedure for imposing prescribed surface temperature given, for example, from thermal-fluid dynamics simulations is proposed for the thermomechanical floating frame of reference formulation. Using several numerical examples, simulation capabilities of the thermomechanical floating frame of reference formulation model are demonstrated for multibody dynamics applications. Numerical results show good agreement with the nonlinear thermomechanical finite element solutions considering the large rotational motion with substantial reduction in the model dimensionality and computational time.
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Glaspell, Aspen, Jose Angel Diosdado De la Pena, Saroj Dahal, Sandesh Neupane, Jae Joong Ryu i Kyosung Choo. "Heat Transfer and Structural Characteristics of Dissimilar Joints Joining Ti-64 and NiTi via Laser Welding". Energies 15, nr 19 (22.09.2022): 6949. http://dx.doi.org/10.3390/en15196949.
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This study investigates the thermal-stress characteristics of a bi-metallic Ti-6Al-4V-Nitinol butt joints manufactured via laser welding. Particularly, the thermal profile along the weld interface and the deformation profile of the finished welded workpiece. A decoupled transient thermomechanical simulation model was constructed to recreate the welding process. This decoupled thermomechanical simulation model consisted of two transient simulation models. A transient thermal simulation model and a transient structural simulation model, with the thermal history of the transient thermal model being fed into the transient structural model. Both the thermal and structural portions of the model utilized temperature-dependent thermal and structural properties of Ti-6Al-4V and Nitinol. The temperature profile of the transient thermal-stress model aligns with the experimental thermal profile within 5% error. The deformation profile also matches the experimental results within 5% error. This approach to modeling laser welding can stand as a guide to predict both thermal and deformation profiles generated during the laser welding process.
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Becker, Eric, Laurent Langlois, Véronique Favier i Régis Bigot. "Thermomechanical Modelling and Simulation of C38 Thixoextrusion Steel". Solid State Phenomena 217-218 (wrzesień 2014): 130–37. http://dx.doi.org/10.4028/www.scientific.net/ssp.217-218.130.
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The present paper focuses the modelling and the simulation of a direct thixoextrusion test achieved on C38 semi-solid steel. Many parameters related to thermal, mechanical, material features are involved but are currently unknown. Consequently to validate the modelling and the simulation, it is important to get various experimental informations during the test and to correlate them with simulated results. In a previous paper (Becker et al, 2008), the force-displacement curve, the temperature within the die, the macro and micro structure obtained for different process parameters during thixoextrusion of C38 were investigated. In this work, those results are correlated to those obtained by simulations of the processing. The simulations were performed using the commercial software Forge®. The thermal modelling is based on the heat equation and the thermal boundary conditions involving the heat losses, the thermal conduction within the semi-solid slug and the die and the plastic dissipation as heat source. The latent heat associated to the liquid-solid phase transformation is not considered here. The constitutive equation of the material is given by a multi-scale modelling based on micromechanics and homogenization techniques, labelled as micro-macro modelling (Favier et al, 2009). Friction is modelled using the usual modified Tresca equation. The parameters of the model are determined (i) using literature results and (ii) to match various experimental measurements obtained during the test and described in Becker et al (2008) such as the die temperature during the test and the load-displacement curve. Comparisons between experimental and simulated reveal the presence of complex temperature field and the presence of zones having very low viscosities. These zones contribute actively to the semi-solid material flow.
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Behseresht, Saeed, i Young Ho Park. "Additive Manufacturing of Composite Polymers: Thermomechanical FEA and Experimental Study". Materials 17, nr 8 (20.04.2024): 1912. http://dx.doi.org/10.3390/ma17081912.
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This study presents a comprehensive approach for simulating the additive manufacturing process of semi-crystalline composite polymers using Fused Deposition Modeling (FDM). By combining thermomechanical Finite Element Analysis (FEA) with experimental validation, our main objective is to comprehend and model the complex behaviors of 50 wt.% carbon fiber-reinforced Polyphenylene Sulfide (CF PPS) during FDM printing. The simulations of the FDM process encompass various theoretical aspects, including heat transfer, orthotropic thermal properties, thermal dissipation mechanisms, polymer crystallization, anisotropic viscoelasticity, and material shrinkage. We utilize Abaqus user subroutines such as UMATHT for thermal orthotropic constitutive behavior, UEPACTIVATIONVOL for progressive activation of elements, and ORIENT for material orientation. Mechanical behavior is characterized using a Maxwell model for viscoelastic materials, incorporating a dual non-isothermal crystallization kinetics model within the UMAT subroutine. Our approach is validated by comparing nodal temperature distributions obtained from both the Abaqus built-in AM Modeler and our user subroutines, showing close agreement and demonstrating the effectiveness of our simulation methods. Experimental verification further confirms the accuracy of our simulation techniques. The mechanical analysis investigates residual stresses and distortions, with particular emphasis on the critical transverse in-plane stress component. This study offers valuable insights into accurately simulating thermomechanical behaviors in additive manufacturing of composite polymers.
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Leppänen, Anton, Asko Kumpula, Joona Vaara, Massimo Cattarinussi, Juho Könnö i Tero Frondelius. "Thermomechanical Fatigue Analysis of Cylinder Head". Rakenteiden Mekaniikka 50, nr 3 (21.08.2017): 182–85. http://dx.doi.org/10.23998/rm.64743.
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The finite element simulation of a cylinder head has been carried out with Abaqus Standard using Z-mat material model, with thermal boundary conditions coming from combined conjugate heat transfer and gas-exchange simulations. The fatigue post-processing of results has been done with Z-post software using ONERA fatigue model. The resulting lifetime values have been found out to correspond well to observations from the field.
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Wang, Xiu Juan, Xiu Ting Zheng, Wei Zheng i Si Zhu Wu. "Molecular Simulation of Polycarbonate and Thermomechanical Analysis". Applied Mechanics and Materials 556-562 (maj 2014): 441–44. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.441.
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The influence of molecular structure of polycarbonate on performance was systematically investigated by both experiment and molecular simulation. Different types of polycarbonate molecular chain models were built and analyzed by molecular simulation method. By combining experimental and simulation results, it is concluded that the polycarbonate-OQ2720 has better thermal stability, mechanical properties and optical performance, which is a better choice for aviation materials and manufacturing process.
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Alekseev, M. V., N. G. Sudobin, A. A. Kuleshov i E. B. Savenkov. "Mathematical Simulation of Thermomechanics in an Impermeable Porous Medium". Herald of the Bauman Moscow State Technical University. Series Natural Sciences, nr 4 (91) (sierpień 2020): 4–23. http://dx.doi.org/10.18698/1812-3368-2020-4-4-23.
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The paper reports on mathematically simulating behaviour of a porous medium featuring isolated interstices filled with a chemically active substance by using a mathematical model of thermomechanics in the matrix and thermochemical processes inside the pores. We used three-dimensional thermomechanical equations to describe the behaviour of the medium. A lumped-element model accounting for chemical reactions and phase equilibrium describes the processes in pores. We outline the mathematical model of the medium and the respective computational algorithm. We provide parametric computation results using realistic thermophysical and thermodynamical parameters, composition of the organic substance found inside pores (products of thermal decomposition of kerogen) and chemical reactions, which show that it is necessary to employ complex, interconnected models to simulate the process class under consideration
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Islam, M. D., i Ger Kelly. "Thermal stress and thermomechanical simulation of embedded electronic packaging". International Journal of Nanomanufacturing 1, nr 4 (2007): 516. http://dx.doi.org/10.1504/ijnm.2007.014571.
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Mani, Hossein, Aboozar Taherizadeh, Behzad Sadeghian, Behzad Sadeghi i Pasquale Cavaliere. "Thermal–Mechanical and Microstructural Simulation of Rotary Friction Welding Processes by Using Finite Element Method". Materials 17, nr 4 (8.02.2024): 815. http://dx.doi.org/10.3390/ma17040815.
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Rotary friction welding is one of the most crucial techniques for joining different parts in advanced industries. Experimentally measuring the history of thermomechanical and microstructural parameters of this process can be a significant challenge and incurs high costs. To address these challenges, the finite element method was used to simulate thermomechanical and microstructural aspects of the welding of identical superalloy Inconel 718 tubes. Numerical simulation results were used to compute essential mechanical and metallurgical parameters such as temperature, strain, strain rate, volume fraction of dynamic recrystallization, and grain size distribution. These parameters were subsequently verified using experimental test results. The Johnson–Avrami model was utilized in the microstructural simulation to convert thermomechanical parameters into metallurgical factors, employing a FORTRAN subroutine. The calculated thickness of the recrystallization zone in the wall was 480 and 850 μm at the tube wall’s center and edge, respectively. These values were reported from experimental measurements as 500 and 800 μm, respectively. The predicted grain size changes from the center to the edge of the wall thickness, near the weld interface, ranged from 2.07 to 2.15 μm, comparable to the experimental measurements ranging from 1.9 to 2.2 μm. Various curves are also presented to explore the correlation between thermomechanical and microstructural parameters, with the experimental results revealing predictable microstructure evolutions correlated with thermomechanical changes.
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Litoš, P., M. Švantner i M. Honner. "Simulation of Strain Gauge Thermal Effects During Residual Stress Hole Drilling Measurements". Journal of Strain Analysis for Engineering Design 40, nr 7 (1.10.2005): 611–19. http://dx.doi.org/10.1243/030932405x30812.
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The hole drilling residual stress measuring method is based on drilling a small hole in a material sample and measuring the strain relieved in the hole vicinity by a special strain gauge rosette. The temperature and thermal strain induced by the drilling process can cause significant errors in the relieved strain measurement. The paper deals with computer simulation of the thermomechanical process in the sample during drilling. The first part is devoted to the evaluation of heat flux from the drilling tool to the drilled material using the sample surface temperature measured by thermography. The second part deals with determination of real strain and strain gauge thermal output (apparent strain) at the strain gauge location during and after drilling. The paper describes the computer modelling technique for solving an indirect thermal problem of drilling heat flux determination and a direct thermomechanical problem for a set of the process alternatives. Comparisons of simulated and experimentally determined temperatures and strains are presented.
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Wang, Youshan, Yintao Wei, Xijin Feng i Zhenhan Yao. "Finite Element Analysis of the Thermal Characteristics and Parametric Study of Steady Rolling Tires". Tire Science and Technology 40, nr 3 (1.10.2012): 201–18. http://dx.doi.org/10.2346/tire.12.400304.
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ABSTRACT This article presents a numerical thermomechanical analysis and parametric study of steady rolling tires that are treated as axisymmetric structures for simplification. Under periodic stress–strain cycles, during tire rolling, internal heat will be generated because of energy loss from the tire material. A general-purpose, finite element program is used to model this two-dimensional heat conduction with distributed, internal heat sources, whereas an in-house code for tire simulation performs the underlying three-dimensional structure and heat-generation rate analysis. The tire belts and carcasses are modeled using layer solid elements with transverse, isotropic, thermomechanical properties, whereas the rubber components are made of isotropic materials. The goal of this article is to develop a simple and easy methodology for simulating tire thermomechanical behavior. Furthermore, the parametric study for the highest shoulder temperature (HST), which is widely accepted as one of the triggers of tire failure, has been performed. The HST sensitivities to the selected parameters have been computed from the simulated temperature fields under different conditions, which provide a guidance to improve the tire structural, material, and pattern designs.
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Depradeux, L., i J. F. Jullien. "Experimental and numerical simulation of thermomechanical phenomena during a TIG welding process". Journal de Physique IV 120 (grudzień 2004): 697–704. http://dx.doi.org/10.1051/jp4:2004120080.
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In this study, a parallel experimental and numerical simulation of phenomena that take place in the Heat Affected Zone during TIG welding on 316L stainless steel is presented. The aim of this study is to predict by numerical simulation residual stresses and distortions generated by the welding process. For the experiment, a very simple geometry with reduced dimensions is considered: the specimens are disks, made of 316L. The discs are heated in the central zone in order to reproduce thermo-mechanical cycles that take place in the HAZ during a TIG welding process. During and after thermal cycle, a large quantity of measurement is provided, and allows to compare the results of different numerical models used in the simulations. The comparative thermal and mechanical analysis allows to assess the general ability of the numerical models to describe the structural behavior. The importance of the heat input rate and material characteristics is also investigated.
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Piekarska, W., M. Kubiak i Z. Saternus. "Numerical Simulation of Deformations in T-Joint Welded by the Laser Beam". Archives of Metallurgy and Materials 58, nr 4 (1.12.2013): 1391–96. http://dx.doi.org/10.2478/amm-2013-0181.
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Abstract Numerical simulation of deformations in laser welded T-joint is carried out in this study. The analysis is performed using Abaqus FEA engineering software. Additional author’s numerical subroutines, written in FORTRAN programming language are used in computer simulations where models of the distribution of movable laser beam heat source, kinetics of phase transformations in solid state as well as thermal and structural strain are implemented. Thermomechanical properties of welded material changing with temperature are taken into account in the analysis. Presented results of numerical simulations performed for the laser beam welding of two perpendicularly arranged sheets include temperature distribution, kinetics of phase transformations in solid state, thermal and structural strain as well as estimated welding deformations.
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Tekriwal, P., i J. Mazumder. "Transient and Residual Thermal Strain-Stress Analysis of GMAW". Journal of Engineering Materials and Technology 113, nr 3 (1.07.1991): 336–43. http://dx.doi.org/10.1115/1.2903415.
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A three-dimensional transient thermomechanical analysis has been performed for the Gas Metal Arc Welding process using the finite element method. Because the heat generated due to elasto-visco-plastic straining in welding is negligible in comparison to the arc heat input, the thermomechanical analysis is uncoupled into two parts. The first part performs a three-dimensional transient heat transfer analysis and computes entire thermal history of the weldment. The second part then uses results of the first part and performs a three-dimensional transient thermo-elastoplastic analysis to compute transient and residual distortions, strains and stresses in the weld. The thermomechanical model incorporates all the thermophysical and mechanical properties of the material as functions of temperature. Boundary conditions used in the numerical simulation are quite general and are matched with the experiment carried out to measure transient strains in the mild steel (0.22 percent carbon steel) weld. Good qualitative agreement was achieved between calculated and measured transient strains.
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Lurie, S. A., P. A. Belov i A. V. Volkov. "Variational formulation of thermomechanical problems". Uchenye Zapiski Kazanskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki 165, nr 3 (12.01.2024): 246–63. http://dx.doi.org/10.26907/2541-7746.2023.3.246-263.
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This article proposes that a 4D space-time continuum is used for building variational thermomechanical continuum models. In order to identify physical constants in reversible processes, physically justified hypotheses were formulated. They are the hypotheses of complementary shear stress, classical dependence of momentum on velocity, and heat flow potentiality (generalized Maxwell–Cattaneo law). The Duhamel–Neumann law was assumed to be classical. In the considered model, the generalized Maxwell–Cattaneo and Duhamel–Neumann laws were not introduced phenomenologically. They were derived from the compatibility equations by excluding thermal potential from the constitutive equations for temperature, heat flow, and pressure. Dissipation channels were considered as the simplest non-integrable variational forms, which are linear in the variations of arguments. As a result, a variational principle that generalizes L.I. Sedov’s principle was developed. It is a consequence of the virtual work principle and termed as the difference between the variation of the Lagrangian of reversible thermomechanical processes and the algebraic sum of dissipation channels. It was proved that for the classical thermomechanical processes, with second-order differential equations, there can only exist six dissipation channels. Two of them determine dissipation in an uncoupled system – in the equations of motion and heat balance. The remaining four channels define coupling effects in coupled problems of dissipative thermomechanics.
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Osman, Ibrahim Sufian, i Nasir Ghazi Hariri. "Thermal Investigation and Optimized Design of a Novel Solar Self-Driven Thermomechanical Actuator". Sustainability 14, nr 9 (23.04.2022): 5078. http://dx.doi.org/10.3390/su14095078.
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As the world moves toward cleaner and greener sources of energy, the use of solar energy appeals the most for countries in the Middle East and North Africa (MENA) region, since they have an abundant amount of solar radiation throughout the year. This paper offers a novel design for a shape memory alloy (SMA) actuator that uses solar energy to trigger thermomechanical behavior. Additionally, the proposed design of the thermomechanical actuator aims to be a piston-based linear actuator covered by a solar heat collector (SHC). Furthermore, the thermal behavior of the actuator has been studied in detail using a simulation-based study under the real-time weather conditions of Dammam city, Kingdom of Saudi Arabia (KSA). The thermal study proves that the optimized design of the thermomechanical actuator has achieved a minimum daily temperature variation of 10 °C, which enables the SMA-based thermomechanical actuator to operate in a daily manner throughout the year. Moreover, the presented numerical results show that the proposed thermomechanical actuator requires a twice-maintenance routine yearly. Additionally, it has been observed that the SHC, which is the central part of the designed thermomechanical actuator, can increase the temperature inside the actuator by about 15 °C more than ambient temperature. The proposed study adds to the body of knowledge a design for a passive, solar-driven, and self-actuating smart thermomechanical SMA actuator that is capable of integration with various solar applications, such as the cleaning and tracking of photovoltaic systems.
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Suyitno, Dmitry G. Eskin i Laurens Katgerman. "Thermal Contraction of AA5182 for Prediction of Ingot Distortions". Key Engineering Materials 306-308 (marzec 2006): 977–82. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.977.
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Shape distortions and hot cracking during casting are strongly related to thermal contraction during and after solidification. The understanding of this phenomenon is crucial in designing defect-free cast products and in numerical simulation of their thermomechanical behavior. This paper presents the results of experimental and numerical simulation work on the thermal contraction during and after solidification of a commercial AA5182 alloy. In the specially developed experimental set-up, the contraction is measured simultaneously with temperature while the material solidifies and cools down in the solid state. An elasto-viscoplastic constitutive model fitted to experimental data is used in finite element simulations of the contraction process. The implementation of thermal contraction data for ingot distortion during the start-up phase of casting is also included. The results show that the contraction starts at a certain temperature in the nonequilibrium solidification range, close to the non-equilibrium solidus. Good agreement is found between simulation and experimental results.
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Desrayaud, Christophe. "Simplified Simulation of the Friction Stir Welding Process. Influence of the Boundary Conditions Modelling". Materials Science Forum 706-709 (styczeń 2012): 2943–49. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2943.
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A simple three dimensional thermomechanical model for FSW is used in the present paper. It is developed from the model proposed by Heurtier [1] improved by Jacquin [10] to account for the eulerian cooling flux due to the tool motion during welding. The velocity fields used to describe the bulk flow around the tool are introduced in the particular derivative of the thermal equilibrium equation. The complete thermomechanical history of the material during the process can then be accessed by temperature and strain rate contours.
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Ma, Zhu, Changzheng Shi, Hegao Wu i Songzi Liu. "Structural Behavior of Massive Reinforced Concrete Structures Exposed to Thermomechanical Loads". Energies 15, nr 7 (6.04.2022): 2671. http://dx.doi.org/10.3390/en15072671.
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Massive reinforced concrete (MRC) structures are utilized in a variety of applications where both mechanical and thermal properties are of concern. A 1:2 large-scale test model of the steel-lined reinforced concrete penstock (a kind of MRC) and a coupled thermomechanical numerical analysis are both implemented to investigate the thermomechanical effects on structural behavior. Three different temperature fields and eight temperature gradients are selected to explore how the temperature affects the crack width, steel stress, and deformation. The results show that the numerical simulation results are consistent with the experimental results and that this method can be applied to other similar MRC structure analysis. The thermal effect can cause 10−3~10−2 mm thermal crack width and ±45 MPa thermal stress and this may lead the total crack width to exceed the limited value and the reinforcement stress beyond the yield strength. Consequently, the influence of the thermomechanical loads cannot be ignored and the corresponding temperature control measures must be taken to ensure structural safety and durability.
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Wang, Jun, Yingjie Xu, Weihong Zhang i Xuanchang Ren. "Thermomechanical Modeling of Amorphous Glassy Polymer Undergoing Large Viscoplastic Deformation: 3-Points Bending and Gas-Blow Forming". Polymers 11, nr 4 (10.04.2019): 654. http://dx.doi.org/10.3390/polym11040654.
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Polymeric products are mostly manufactured by warm mechanical processes, wherein large viscoplastic deformation and the thermomechanical coupling effect are highly involved. To capture such intricate behavior of the amorphous glassy polymers, this paper develops a finite-strain and thermomechanically-coupled constitutive model, which is based on a tripartite decomposition of the deformation gradient into elastic, viscoplastic, and thermal components. Constitutive equations are formulated with respect to the spatial configuration in terms of the Eulerian Hencky strain rate and the Jaumann rate of Kirchhoff stress. Hyperelasticity, the viscoplastic flow rule, strain softening and hardening, the criterion for viscoplasticity, and temperature evolution are derived within the finite-strain framework. Experimental data obtained in uniaxial tensile tests and three-point bending tests of polycarbonates are used to validate the numerical efficiency and stability of the model. Finally, the proposed model is used to simulate the gas-blow forming process of a polycarbonate sheet. Simulation results demonstrate well the capability of the model to represent large viscoplastic deformation and the thermomechanical coupling effect of amorphous glassy polymers.
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Vemanaboina, Harinadh, Edison Gundabattini, Kaushik Kumar, Paolo Ferro i B. Sridhar Babu. "Thermal and Residual Stress Distributions in Inconel 625 Butt-Welded Plates: Simulation and Experimental Validation". Advances in Materials Science and Engineering 2021 (19.10.2021): 1–12. http://dx.doi.org/10.1155/2021/3948129.
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Thermal and residual stress distributions induced by the gas tungsten arc welding (GTAW) process on Inconel 625 were studied using numerical simulation and experiments. A multi-pass welding model was developed that uses a volumetric heat source. Thermomechanical analysis is carried out to assess the Thermal and residual stress distributions. Experiments were carried out with 5 mm thick Inconel 625 plates. X-ray diffraction techniques were used to measure residual stresses, and IR thermometry was employed to capture the temperature values on the welded joints. Simulations were performed with ANSYS numerical code, and a close agreement was found between the predicted and experimentally measured residual stress. Thermal measurements were collected pass by pass from the analysis, and the agreement was 9.08%. The agreement between the measured and analysed residual stress was 11%.
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Boudjaza, Samia, Abdelmadjid Chehhat i Billel Rebai. "Time dependent thermal behavior of geothermal energy pile (GEP) for summer and winter periods using CFD analysis". STUDIES IN ENGINEERING AND EXACT SCIENCES 5, nr 2 (29.11.2024): e11283. https://doi.org/10.54021/seesv5n2-591.
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This study investigates the thermomechanical behavior of geothermal energy piles, which serve the dual function of providing structural support and facilitating heat exchange with the surrounding ground. The thermal energy transfer is achieved by circulating a working fluid through U-shaped heat exchanger pipes embedded in the pile, enabling cooling during summer and heating in winter. Unlike conventional piles, the thermomechanical coupling in energy piles alters their load transfer mechanisms, with distinct responses during summer (cooling) and winter (heating) periods that require separate evaluation. While energy pile modeling is relatively new compared to borehole systems, both share operational similarities. To explore this, a numerical simulation was conducted using ANSYS Fluent, incorporating a polyethylene tube, concrete, and surrounding soil. The analysis was performed under various Reynolds numbers (500, 1000, 1500, and 2000) and time intervals (60 min, 360 min, and 720 min) to capture the time-dependent thermal behavior for both cooling and heating periods. The simulations demonstrated satisfactory outcomes, suggesting promising potential for geothermal energy applications in Algerian residential buildings.
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RODOVALHO, F. S., i M. R. S. CORRÊA. "Thermal simulation of prisms with concrete blocks in a fire situation". Revista IBRACON de Estruturas e Materiais 12, nr 3 (czerwiec 2019): 638–57. http://dx.doi.org/10.1590/s1983-41952019000300011.
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Abstract The purpose of the current study is to verify the thermal insulation capacity of concrete block masonry in a fire situation through the thermal simulation of prisms. Initially, a prism with mortar coating on the face exposed to fire was numerically simulated and compared to experimental results provided by a company in order to validate the block thermal properties. To represent air in the block cavities, fluid-structure interaction was used in ABAQUS software. The uncoated and mortar-coated prisms on both sides were analyzed in a fire situation. The thermal insulation of the uncoated prism was maintained for more than 60 minutes and with the application of coating on both faces there was an increase of 59% of this time. The thermal fields were generated, thus leading to future thermomechanical analysis.
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Wang, Xiu Juan, Xiu Ting Zheng, Meng Song, Xiu Ying Zhao i Si Zhu Wu. "Thermomechanical Analysis of Poly (Bisphenol-A Carbonate) Performance and Molecular Simulation". Advanced Materials Research 781-784 (wrzesień 2013): 576–79. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.576.
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This work studied the influence of different molecular structure of polycarbonate on its properties. Different types of polycarbonate molecular chain models were built by molecular simulation method. By combining experimental and molecular dynamic simulation results, it is concluded that the polycarbonate-OQ2720 has better thermal stability, mechanical properties and optical performance, which is a better choice for aviation materials and manufacturing process.
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Ali, Mahmoud, Thomas Sayet, Alain Gasser i Eric Blond. "Transient Thermo-Mechanical Analysis of Steel Ladle Refractory Linings Using Mechanical Homogenization Approach". Ceramics 3, nr 2 (2.04.2020): 171–89. http://dx.doi.org/10.3390/ceramics3020016.
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Mortarless refractory masonry structures are widely used in the steel industry for the linings of many high-temperature industrial applications including steel ladles. The design and optimization of these components require accurate numerical models that consider the presence of joints, as well as joint closure and opening due to cyclic heating and cooling. The present work reports on the formulation, numerical implementation, validation, and application of homogenized numerical models for the simulation of refractory masonry structures with dry joints. The validated constitutive model has been used to simulate a steel ladle and analyze its transient thermomechanical behavior during a typical thermal cycle of a steel ladle. A 3D solution domain and enhanced thermal and mechanical boundary conditions have been used. Parametric studies to investigate the impact of joint thickness on the thermomechanical response of the ladle have been carried out. The results clearly demonstrate that the thermomechanical behavior of mortarless masonry is orthotropic and nonlinear due to the gradual closure and reopening of the joints with the increase and decrease in temperature. In addition, resulting thermal stresses increase with the increase in temperature and decrease with the increase in joint thickness.
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Kunda, Sudip, Noah J. Schmelzer, Akhilesh Pedgaonkar, Jack E. Rees, Samuel D. Dunham, Charles K. C. Lieou, Justin C. M. Langbaum i Curt A. Bronkhorst. "Study of the Thermomechanical Behavior of Single-Crystal and Polycrystal Copper". Metals 14, nr 9 (22.09.2024): 1086. http://dx.doi.org/10.3390/met14091086.
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This research paper presents an experimental, theoretical, and numerical study of the thermomechanical behavior of single-crystal and polycrystal copper under uniaxial stress compression loading at varying rates of deformation. The thermomechanical theory is based on a thermodynamically consistent framework for single-crystal face-centered cubic metals, and assumes that all plastic power is partitioned between stored energy due to dislocation structure evolution (configurational) and thermal (kinetic vibrational) energy. An expression for the Taylor–Quinney factor is proposed, which is a simple function of effective temperature and is allowed by second-law restrictions. This single-crystal model is used for the study of single- and polycrystal copper. New polycrystal thermomechanical experimental results are presented at varying strain rates. The temperature evolution on the surface of the polycrystal samples is measured using mounted thermocouples. Thermomechanical numerical single- and polycrystal simulations were performed for all experimental conditions ranging between 10−3 and 5 × 103 s−1. A Taylor homogenization model is used to represent polycrystal behavior. The numerical simulations of all conditions compare reasonable well with experimental results for both stress and temperature evolution. Given our lack of understanding of the mechanisms responsible for the coupling of dislocation glide and atomic vibration, this implies that the proposed theory is a reasonably accurate approximation of the single-crystal thermomechanics.
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Li, Hui, Hanbo Zhang, Yixiong Zhang, Xiaoming Bai, Xuejiao Shao i Bingyang Wu. "Coupled Non-Ordinary State-Based Peridynamics Model for Ductile and Brittle Solids Subjected to Thermal Shocks". Applied Sciences 14, nr 16 (7.08.2024): 6927. http://dx.doi.org/10.3390/app14166927.
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A coupled thermomechanical non-ordinary state-based peridynamics (NOSB-PD) model is developed to simulate the dynamic response arising from temperature and to predict the crack propagation with thermal shocks in brittle and ductile solids. A unified multiaxial constitutive model with damage growth is proposed to simultaneously describe the ductile and brittle fracture mechanisms. The main idea is the use of Lemaitre’s model to describe ductile damage behavior and the use of tensile strength instead of yield stress in Lemaitre’s model to describe brittle damage behavior. A damage-related fracture criterion is presented in the PD framework to predict crack propagation, which avoids numerical oscillations when using the traditional bond stretch criterion. To capture the dynamic plastic response induced by thermal shocks, the time and stress integration are achieved by an alternating solving strategy and implicit return-mapping algorithm. Several numerical examples are presented to show the performance of the proposed model. Firstly, a thermomechanical problem simulation based on both the proposed model and the FEM illustrate the accuracy of the proposed model in studying the thermal deformation. Moreover, a benchmark brittle fracture example of the Kalthoff–Winkler impact test is simulated, and the crack path and angle are similar to the experimental observations. In addition, the simulation of ductile fracture under different loads illustrates the effect of temperature on crack propagation. Finally, the simulation of the 2D quenching test shows the ability of the proposed model in predicting crack propagation under thermal shocks.
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Li, Jianwei. "Thermomechanical constitutive equations for glass and numerical simulation on automobile glass forming technology". Glass Technology: European Journal of Glass Science and Technology Part A 63, nr 4 (2022): 122–28. http://dx.doi.org/10.13036/17533546.63.4.006.
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To establish a comprehensive numerical model for automotive glass forming, firstly, this paper conducts material tests of 3·2 SG glass to obtain detailed material properties. Through thermal expansion experiments, the thermal expansion coefficients including glassy and liquid states are obtained; then by using three-point bending stress relaxation and differential scanning calorimetry experiments, the stress relaxation and structural relaxation properties of the glass are obtained. Finally, a comparison analysis of the simulation and the actual spherical deviation for an actual automobile glass product is carried out. The result shows that the product simulation and the actual product spherical deviation correspond. The maximum value of the spherical deviation is within 0·94 mm between simulation and the actual product spherical deviation. The accuracy can meet the design requirements, and the established numerical model is reliable.
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Koeune, Roxane, i Jean Philippe Ponthot. "A Thermomechanical Model Dedicated to Thixoforming. Application to Semi-Solid Forming". Solid State Phenomena 192-193 (październik 2012): 269–75. http://dx.doi.org/10.4028/www.scientific.net/ssp.192-193.269.
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This paper deals with the simulation of two extrusion tests by thixoforming: a non stationary extrusion test and a double-cup extrusion test. The simulations are based on a thermo-mechanical one-phase constitutive law that has been presented in details in previous papers. A campaign of experimental extrusion testing has been conducted on a steel alloy and the comparison between the numerical and experimental results will validate the model under study. A new feature that has been added to the model is also discussed: the introduction of the phase change thermal effects such as the fusion latent heat and the contraction of the material.
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Tamer, Ozan, Fabian Walter, Michael Sinapius i Markus Böl. "A Computational Geometric Parameter Optimization of the Thermomechanical Deicing Concept". Actuators 11, nr 8 (5.08.2022): 223. http://dx.doi.org/10.3390/act11080223.
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Ice formation on aerodynamic surfaces is a safety-related issue in aviation. Thermal, mechanical, or hybrid systems are used to prevent or eliminate ice formation. To increase energy efficiency, new methods are being researched and tested, using new materials. This article aims to investigate in detail the geometrical parameters of a novel thermomechanical deicing concept based on the shape memory effect. The thermomechanical behavior of a shape memory alloy wire embedded in an elastomer can be described, using the transformation expansion coefficient. The approach includes the nonlinear phase transformation and the linear expansion of the alloy. Simulation results using the above approach are compared with experimental results. In addition, a parameter study of the geometric quantities is presented, where the individual effects of these quantities are investigated assuming that there is a block-like ice layer on the surface. The results for the behavior of the SMA show promising results in terms of describing the thermomechanical behavior of the wire. However, deviations are still observed in the thermal behavior of the embedding matrix.
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Olshevskiy, Alexander, Alexey Olshevskiy, Oleg Berdnikov i Chang-Wan Kim. "Finite element analysis of railway disc brake considering structural, thermal, and wear phenomena". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, nr 7 (15.11.2011): 1845–60. http://dx.doi.org/10.1177/0954406211428705.
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The purpose of this research is to identify the thermomechanical factors to be considered in simulation of the braking process, calculation of the distribution of the contact pressure, and temperature and obtain wear patterns for the disc brake system in operation. The factors affecting the temperature distribution and stress–strain state of disc brakes in railway vehicles are analyzed. The mutual influence of the thermal problem and contact problem was considered. The results of the numerical simulations for the finite element models can be used in optimizing the disc brake design in order to reduce wear and provide higher reliability of the braking system.
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Marin-Montin, Jorge, Eduardo Roque, Yading Xu, Branko Šavija, Juan Carlos Serrano-Ruiz i Francisco Montero-Chacón. "Thermomechanical Performance Analysis of Novel Cement-Based Building Envelopes with Enhanced Passive Insulation Properties". Materials 15, nr 14 (15.07.2022): 4925. http://dx.doi.org/10.3390/ma15144925.
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The design of new insulating envelopes is a direct route towards energy efficient buildings. The combinations of novel materials, such as phase-change (PCM), and advanced manufacturing techniques, such as additive manufacturing, may harness important changes in the designing of building envelopes. In this work we propose a novel methodology for the design of cement-based building envelopes. Namely, we combined the use of a multiscale, multiphysical simulation framework with advanced synthesis techniques, such as the use of phase-change materials and additive manufacturing for the design of concrete envelopes with enhanced insulation properties. At the material scale, microencapsulated PCMs are added to a cementitious matrix to increase heat storage. Next, at the component level, we create novel designs for the blocks, here defined as HEXCEM, by means of additive manufacturing. The material and component design process is strongly supported on heat transfer simulations with the use of the finite element method. Effective thermal properties of the mixes can be obtained and subsequently used in macroscale simulations to account for the effect of the volume fraction of PCMs. From the experimental and numerical tests, we report an increase in the the thermal inertia, which results in thermal comfort indoors.
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Kurcsics, Mark, Luzia Hahn i Peter Eberhard. "Transient Structural, Thermal and Optical Performance (STOP) Analysis with Accelerated Thermomechanical Computation". EPJ Web of Conferences 309 (2024): 03025. http://dx.doi.org/10.1051/epjconf/202430903025.
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Mechanical and thermal disturbances in optical systems are attracting increasing attention as accuracy requirements rise. For this reason, it is necessary to consider these disturbances at an early stage in the design process. This can be done by a holistic multiphysical opto-thermo-mechanical simulation. Such an approach is presented with a focus on efficient thermomechanical computation through a quasi-static approximation.
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Vandevelde, Bart, Eric Beyne, Kouchi (G Q. ). Zhang, Jo Caers, Dirk Vandepitte i Martine Baelmans. "Parameterized Modeling of Thermomechanical Reliability for CSP Assemblies". Journal of Electronic Packaging 125, nr 4 (1.12.2003): 498–505. http://dx.doi.org/10.1115/1.1604150.
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Finite element modeling is widely used for estimating the solder joint reliability of electronic packages. In this study, the electronic package is a CSP mounted on a printed circuit board (PCB) using an area array of solder joints varying from 5×4 up to 7×7. An empirical model for estimating the reliability of CSP solder joints is derived by correlating the simulated strains to thermal cycling results for 20 different sample configurations. This empirical model translates the inelastic strains calculated by nonlinear three-dimensional (3D) finite element simulations into a reliability estimation (N50% or N100 ppm). By comparing with the results of reliability tests, it can be concluded that this model is accurate and consistent for analyzing the effect of solder joint geometry. Afterwards, parameter sensitivity analysis was conducted by integrating a design of experiment (DOE) analysis with the reliable solder fatigue prediction models, following the method of simulation-based optimization. Several parameters are analyzed: the PCB parameters (elastic modulus, coefficient of thermal expansion, thickness), the chip dimensions (area array configuration), and the parameters defining the solder joint geometry (substrate and chip pad diameter, solder volume). The first study analyzes how the solder joint geometry influences the CSP reliability. A second study is a tolerance analysis for six parameters. These parameters can have a tolerance (=accuracy) of their nominal value, and it is shown that these small tolerances can have a significant influence on the solder joint reliability.
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Nazaret, Fabien, Thierry Cutard i Olivier Barrau. "Sizing of Refractory Castable Gas-Burner Using Thermomechanical Simulations". Advances in Science and Technology 70 (październik 2010): 173–78. http://dx.doi.org/10.4028/www.scientific.net/ast.70.173.
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Damage is a crucial characteristic of refractory castables and has to be considered to simulate correctly the behaviour of refractory structures. But, damage modelling by finite element simulations remains difficult. Indeed, the use of a continuum damage model with softening leads to strain localization phenomena. Numerical results depend on the mesh. Several numerical methods allow solving this meshing dependence by introducing an internal length in the material constitutive laws. In this paper, a regularization method has been applied with the damage plasticity model, considering a scalar value for damage. This model enables to take into account permanent strains due to plasticity and damage before and after the peak stress in tension and compression. Thermomechanical simulations are performed with this model to predict damage in a gas-burner. The damage level is evaluated after a thermal simulation generating high temperature gradients. Interests to take into account damage in the refractory structures are discussed. Sensitivity of results to material properties is studied. This work gives an example of using thermomechanical simulations to improve the design of refractory castable structures and to help in the material choice.
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Darcourt, C., J. M. Roelandt, M. Rachik, D. Deloison i B. Journet. "Thermomechanical analysis applied to the laser beam welding simulation of aeronautical structures". Journal de Physique IV 120 (grudzień 2004): 785–92. http://dx.doi.org/10.1051/jp4:2004120091.
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The present work is being done in the framework of a national program about the lightening of aeronautical structures and describes a three-dimensional finite element simulation of the laser beam welding process. The targeted aeronautical structures are stiffened panels in aluminum alloys, which tend to replace riveted assemblies. Semi-coupled thermomechanical finite element analyses have been carried out to evaluate the magnitude and distribution of welding-induced residual stresses in order to take them into account for fatigue sizing. The finite element code MSC.Marc is used for the different calculations. Specific welding features have been added to the code through the implementation of a moving heat source or an elastoviscoplastic law. Experimental tests have been carried out in order to provide mechanical and thermal databases to the model. Monitored experimental welding have been made for comparisons with the simulation. In particular, results of thermocouple measurements have permitted to improve the thermal model.
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Xu, Chenglong, i Zhi Liu. "Coupled CFD-FEM Simulation of Steel Box Bridge Exposed to Fire". Advances in Civil Engineering 2022 (10.01.2022): 1–12. http://dx.doi.org/10.1155/2022/5889743.
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Increasing fire-induced bridge failures are demanding more precise behavior prediction for the bridges subjected to fires. However, current numerical methods are limited to temperature curves prescribed for building structures, which can misestimate the fire impact significantly. This paper developed a framework coupling the computational dynamics (CFD) method and finite element method (FEM) to predict the performance of fire-exposed bridges. The fire combustion was simulated in CFD software, Fire Dynamic Simulator, to calculate the thermal boundary required by the thermomechanical simulation. Then, the adiabatic surface temperatures and heat transfer coefficient were applied to the FEM model of the entire bridge girder. A sequential coupled thermomechanical FEM simulation was then carried out to evaluate the performance of the fire-exposed bridge, thermally and structurally. The methodology was then validated through a real fire experiment on a steel beam. The fire performance of a simply supported steel box bridge was simulated using the proposed coupled CFD-FEM methodology. Numerical results show that the presented method was able to replicate the inhomogeneous thermomechanical response of box bridges exposed to real fires. The girder failed due to the buckling of a central diaphragm after the ignition of the investigated tanker fire in no more than 10 min. The framework presented in this study is programmatic and friendly to researchers and can be applied for the estimation of bridges in different fire conditions.
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BONETTI, ELENA, PIERLUIGI COLLI i MICHEL FREMOND. "A PHASE FIELD MODEL WITH THERMAL MEMORY GOVERNED BY THE ENTROPY BALANCE". Mathematical Models and Methods in Applied Sciences 13, nr 11 (listopad 2003): 1565–88. http://dx.doi.org/10.1142/s0218202503003033.
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We introduce a thermomechanical model describing dissipative phase transitions with thermal memory in terms of the entropy balance and the principle of virtual power written for microscopic movements. The thermodynamical consistence of this model is verified and existence of solutions is proved for a related initial and boundary value problem.
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Bogard, Virginie, Philippe Revel i Yannick Hetet. "Optimization of Thermomechanical Loading by the Inverse Method". Journal of Engineering Materials and Technology 129, nr 2 (26.06.2006): 207–10. http://dx.doi.org/10.1115/1.2400255.
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This study presents 2D experimental results and the numerical simulations of thermal loads in order to observe their influences on the life of mechanical systems. The experimental and thermal evolution was measured using several thermocouples and an infrared pyrometer. In fact, the thermal loading was determined by the resolution of an inverse process where the parameters of thermal laws were identified by minimizing the difference between the experimental results and the numerical simulations. After this optimization process, the mechanical modeling by the finite element method was carried out by applying the optimized thermal loading. The laws of elastoviscoplastic behavior are applied in the working temperature range of a continuous casting rollers tool. This modeling constitutes a technological means to choose a type of a coating material and its optimum thickness and to test different thermal loads in order to optimize the industrial process and to improve the tool’s life.
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Khodakov, Alexander M., Vitaliy I. Smirnov, Viacheslav A. Sergeev i Ruslan G. Tarasov. "Modeling and analysis of temperature and thermomechanical stress distributions in a multi-chip electronic module". Radioelectronics. Nanosystems. Information Technologies. 16, nr 2 (25.04.2024): 215–22. http://dx.doi.org/10.17725/j.rensit.2024.16.215.
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A mathematical thermomechanical model of a multi-chip electronic module (MEM) containing three silicon dies of high-power transistors fixed with a conductive adhesive on a copper plate placed on a radiator is considered in the form of a system of equations of thermal conductivity and thermoelasticity with specified boundary conditions. As a result of computational studies of the model in the COMSOL Multiphysics software environment, distributions of temperature and thermomechanical stresses in the MEM structural elements were obtained depending on the heating power, the thickness of the adhesive and the size of the model defect in the contact connection of one of the MEM crystals with a copper plate in the form of voids in the adhesive layer. It is shown that voids in the adhesive layer lead to a sharply non-uniform temperature distribution over the crystal area and thermomechanical shear stresses in the contact layer that exceed the maximum permissible values for the adhesive. It has been established that thermomechanical stresses decrease with increasing thickness of the adhesive layer and increase with increasing size of the defect(voids) in this layer. The simulation results are in good agreement with the results of measuring the thermal impedance of power transistor crystals using the modulation method, which indicates the correctness and adequacy of the developed model.
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Collins, Jeff T., Jeremy Nudell, Gary Navrotski, Zunping Liu i Patric Den Hartog. "Establishment of new design criteria for GlidCop® X-ray absorbers". Journal of Synchrotron Radiation 24, nr 2 (20.02.2017): 402–12. http://dx.doi.org/10.1107/s1600577517001734.
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An engineering research program has been conducted at the Advanced Photon Source (APS) in order to determine the thermomechanical conditions that lead to crack formation in GlidCop®, a material commonly used to fabricate X-ray absorbers at X-ray synchrotron facilities. This dispersion-strengthened copper alloy is a proprietary material and detailed technical data of interest to the synchrotron community is limited. The results from the research program have allowed new design criteria to be established for GlidCop® X-ray absorbers based upon the thermomechanically induced fatigue behavior of the material. X-ray power from APS insertion devices was used to expose 30 GlidCop® samples to 10000 thermal loading cycles each under various beam power conditions, and all of the samples were metallurgically examined for crack presence/geometry. In addition, an independent testing facility was hired to measure temperature-dependent mechanical data and uniaxial mechanical fatigue data for numerous GlidCop® samples. Data from these studies support finite element analysis (FEA) simulation and parametric models, allowing the development of a thermal fatigue model and the establishment of new design criteria so that the thermomechanically induced fatigue life of X-ray absorbers may be predicted. It is also demonstrated how the thermal fatigue model can be used as a tool to geometrically optimize X-ray absorber designs.
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Wu, C. T., Wei Hu, Hui-Ping Wang i Hongsheng Lu. "A Robust Numerical Procedure for the Thermomechanical Flow Simulation of Friction Stir Welding Process Using an Adaptive Element-Free Galerkin Method". Mathematical Problems in Engineering 2015 (2015): 1–16. http://dx.doi.org/10.1155/2015/486346.
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A meshfree modeling technique of material flow in the three-dimensional multiphysics thermomechanical friction stir welding process is presented. In this numerical model, the discretization in space is derived by the Element-Free Galerkin method using a Lagrangian meshfree convex approximation. The discrete thermal and mechanical equations are weakly coupled as the time advances using a forward difference scheme. A mortar contact algorithm is employed to model the stirring effect and heat generation due to frictional contact. Heat conductance between contacting bodies is considered as a function of contact pressure. A two-way adaptive procedure is introduced to the coupled thermomechanical system to surpass potential numerical problems associated with the extensive material deformation and spatial discretization. In each adaptive phase, a consistent projection operation utilizing the first-order meshfree convex approximation is performed to remap the solution variables. Finally, a three-dimensional multiphysics thermomechanical coupled friction stir welding problem is analyzed to demonstrate the effectiveness of the present meshfree numerical procedure.
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Li, Haiwang, Dawei Zhang, Ruquan You, Yifan Zou i Song Liu. "Numerical Investigation of the Effects of the Hole Inclination Angle and Blowing Ratio on the Characteristics of Cooling and Stress in an Impingement/Effusion Cooling System". Energies 16, nr 2 (13.01.2023): 937. http://dx.doi.org/10.3390/en16020937.
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Due to the uneven temperature field and temperature gradient introduced by an efficient cooling structure, the analysis of the stress field is necessary. In this study, the cooling characteristics and stress characteristics such as the thermal stress and thermomechanical stress of an impingement/effusion cooling system were investigated by employing a fluid–thermal-structure coupling simulation method. The effects of film hole injection angle (30°–90°) and blowing ratio (0.5–2.0) were studied. The results showed that the film hole shape and the non-uniform temperature field introduced by the cooling structure had a great influence on the stress field distribution. With the increase in the blowing ratio, not only the overall cooling effectiveness of the cooling system increased, but the maximum thermal stress and thermomechanical stress near film holes also increased. The cases with a smaller inclination angle could provide a better cooling performance, but caused a more serious stress concentration of the film hole. However, the thermal stress difference at the leading and trailing edges of the film hole increased with a decreasing inclination angle. The cases with a = 30° and 45° showed serious thermal stress concentration near the hole’s acute region.
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Yuile, Adam, Erik Wiss, David Barth i Steffen Wiese. "Simulation of Mechanical Stresses in BaTiO3 Multilayer Ceramic Capacitors during Desoldering in the Rework of Electronic Assemblies Using a Framework of Computational Fluid Dynamics and Thermomechanical Models". Materials 17, nr 11 (3.06.2024): 2702. http://dx.doi.org/10.3390/ma17112702.
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Multilayer ceramic capacitors (MLCCs) are critical components when thermal processes such as reflow desoldering are used during rework of electronic assemblies. The capacitor’s ferroelectric BaTiO3 body is very brittle. Therefore, thermomechanical stresses can cause crack formation and create conductive paths that may short the capacitor. In order to assess the thermally induced mechanical stresses onto an MLCC during reflow desoldering, simulations were carried out, which make use of a framework of computational fluid dynamics and thermomechanical models within the ANSYS software package. In the first step, CFD simulations were conducted to calculate the transient temperature field in the surrounding of the MLCC component, which was then used as an input for FEM simulations to compute the arising mechanical stresses inside the MLCC. The results of the simulations show that the major contribution to mechanical stresses within the MLCC component comes from the mismatch in thermal expansion between the printed circuit board and the MLCC. The temperature gradients along the MLCC component are rather small and account only for moderate internal stresses within the brittle BaTiO3 body.
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Kenzhegulov, B., Jaroslav Kultan, D. B. Alibiyev i A. Sh Kazhikenova. "Numerical modeling of thermomechanical processes in heat-resistant alloys". Bulletin of the Karaganda University. "Physics" Series 98, nr 2 (30.06.2020): 101–7. http://dx.doi.org/10.31489/2020ph2/101-107.
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This article presents a numerical simulation of thermomechanical processes in heat-resistant alloys. The authors develop the law of temperature distribution along the length of the physical body, which is considered as a rod of alloy EI-617. The authors also investigated the dependence of the magnitude of the elongation of the rod from a given temperature. To do this, the rod is conditionally divided into several elements, and then the study is carried out in one area. To determine the temperature dependence, the temperature distribution field is approximated by a full polynomial of the second degree, and approximation spline functions are introduced. Using a temperature gradient for one element, the functional expression characterizing the total thermal energy is written, first for the (n-1) element, then for the last n-th element. The total thermal energy is expressed by the formula n i i JJ 1 . By minimizing the total thermal energy, we obtain a system of algebraic equations for determining the nodal values of temperatures. Applying the obtained values, the elongation of the element due to thermal expansion is calculated. The relationship between the temperature T, elongation T l , «tensile» force R , and «tensile stress» . is shown in the work. It is shown that with increasing temperature, the above values proportionally increase
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Zivkovic, Dragoljub, Dragan Milcic, Milan Banic i Pedja Milosavljevic. "Thermomechanical finite element analysis of hot water boiler structure". Thermal Science 16, suppl. 2 (2012): 387–98. http://dx.doi.org/10.2298/tsci120503177z.
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The paper presents an application of the Finite Elements Method for stress and strain analysis of the hot water boiler structure. The aim of the research was to investigate the influence of the boiler scale on the thermal stresses and strains of the structure of hot water boilers. Results show that maximum thermal stresses appear in the zone of the pipe carrying wall of the first reversing chamber. This indicates that the most critical part of the boiler are weld spots of the smoke pipes and pipe carrying plate, which in the case of significant scale deposits can lead to cracks in the welds and water leakage from the boiler. The nonlinear effects were taken into account by defining the bilinear isotropic hardening model for all boiler elements. Temperature dependency was defined for all relevant material properties, i. e. isotropic coefficient of thermal expansion, Young?s modulus, and isotropic thermal conductivity. The verification of the FEA model was performed by comparing the measured deformations of the hot water boiler with the simulation results. As a reference object, a Viessmann - Vitomax 200 HW boiler was used, with the installed power of 18.2 MW. CAD modeling was done within the Autodesk Inventor, and stress and strain analysis was performed in the ANSYS Software.
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Wang, Xinwei. "Thermal and Thermomechanical Phenomena in Picosecond Laser Copper Interaction". Journal of Heat Transfer 126, nr 3 (1.06.2004): 355–64. http://dx.doi.org/10.1115/1.1725092.
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Thermal and thermomechanical phenomena in laser metal interaction are of great importance in terms of understanding the underlying mechanisms in laser materials processing, optimizing the efficiency of laser micro-machining, and minimizing laser induced damage. In this work, Molecular Dynamics (MD) simulation is carried out to investigate picosecond laser copper interaction. A method has been developed to account for the laser beam absorption in, and the thermal transport sustained by, free electrons. Superheating is observed, and an evident temperature drop is revealed at the solid-liquid interface, which moves at a speed of 4400 m/s. However, the later phase change from solid to liquid happens in the target simultaneously and no visible movement of solid-liquid interface is observed. The results show that the laser induced stress wave consists of a strong compressive stress and a weak tensile stress. After reflection at the back side of the MD domain, the strong compressive stress becomes a strong tensile stress, which results in a visible drop of the number density of atoms. In the presence of this strong tensile stress, voids have formed in the region near the back side of the MD domain, indicating that the strong tensile stress in laser materials interaction plays an important role in terms of inducing structural damage.