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finite-element modeling of Heat Transfer in Ground Source Energy Systems with Heat Exchanger Pipes

INTERNATIONAL JOURNAL OF GEOMECHANICS 2020年第5期20卷

作者： Gawecka, Klementyna A. Taborda, David M. G. Potts, David M. Sailer, Eleonora Cui, Wenjie Zdravkovic, Lidija Imperial Coll London Dept Civil & Environm Engn London SW7 2AZ England

Ground source energy systems (GSES) utilize low enthalpy geothermal energy and have been recognized as an efficient means of providing low carbon space heating and cooling. This study focuses on GSES where the exchange of heat between the ground and the building is achieved by circulating a fluid through heat exchanger pipes. Although numerical analysis is a powerful tool for exploring the performance of such systems, simulating the highly advective flows inside the heat exchanger pipes can be problematic. This paper presents an efficient approach for modeling these systems using the finite-element method (FEM). The pipes are discretized with line elements and the conductive-advective heat flux along them is solved using the Petrov-Galerkin FEM instead of the conventional Galerkin FEM. Following extensive numerical studies, a modeling approach for simulating heat exchanger pipes, which employs line elements and a special material with enhanced thermal properties, is developed. The modeling approach is then adopted in three-dimensional simulations of two thermal response tests, with an excellent match between the computed and the measured temperatures being obtained.

关键词： Heat transfer Ground source energy system Heat exchanger pipe finite-element modeling Thermal response test

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finite-element modeling of the stresses and fracture during the indentation of hard elastic films on elastic-plastic aluminum substrates

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THIN SOLID FILMS 1999年 355卷 303-310页

作者： Souza, RM Mustoe, GGW Moore, JJ Colorado Sch Mines Adv Coatings & Surface Engn Lab Golden CO 80401 USA Colorado Sch Mines Div Engn Golden CO 80401 USA Bolsista CNPQ Brasilia DF Brazil

In this work, a three-step finite-element analysis was conducted to study the behavior of wear-resistant coatings on soft substrates. Initially, a mesh simulating a system with one hard and elastic film on an elastic-plastic aluminum substrate was developed considering the presence of cracks in the film. A sequence of loading steps was then applied to simulate the deposition (intrinsic) stresses, thermal (extrinsic) stresses and contact stresses during the indentation with normal forces, respectively. Crack propagation was allowed during the indentation step. The influence of film thickness, fracture toughness and elastic modulus was studied based on the radial and shear stresses that developed at the film surface and at the film/substrate inter-face. The results indicated that, under the conditions studied, film cracking was favored in systems with lower thickness and high elastic modulus. The effect of film cracking was also analyzed and a good qualitative comparison was obtained with results found in the literature. (C) 1999 Elsevier Science S.A, All rights reserved.

关键词： finite-element modeling hard elastic films elastic-plastic aluminum substrates

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finite-element modeling of the ballistic impact of fabric armor

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INTERNATIONAL JOURNAL OF IMPACT ENGINEERING 2003年第1期28卷 13-31页

作者： Lim, CT Shim, VPW Ng, YH Natl Univ Singapore Dept Engn Mech Impact Mech Lab Singapore 117576 Singapore

This paper investigates the finite-element simulation of ballistic impact on Twaron(R) fabric through proposing a material model, which incorporates viscoelasticity and a strain-rate-sensitive failure criterion. A non-linear, explicit, three-dimensional finite-element code DYNA3D is used to simulate the response of fabric under high-speed projectile impact. The fabric is modeled using membrane elements. Suitable material properties to account for its viscoelastic nature are obtained through mathematical manipulation of the three-element spring-dashpot model and by use of available experimental data. The ballistic limit, residual velocity, energy absorption and transverse deflection profiles of the fabric are predicted and compared with those from experiment. The limitations of the proposed model, in terms of representing fabric behavior such as frictional effects between yarns and unraveling and fraying of yarns are recognized. Nevertheless, the model provides a fairly accurate representation of the strain-rate-dependent behavior of fabric. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词： finite-element modeling ballistic impact fabric armor energy absorption dynamic material model viscoelasticity

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finite-element modeling AS A TOOL FOR DESIGNING CAPACITIVE POSITION SENSORS

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SENSORS AND ACTUATORS A-PHYSICAL 1995年第1-3期46卷 266-269页

作者： BONSE, MHW MUL, C SPRONCK, JW Delft University of Technology Faculty of Mechanical Engineering and Marine Technology Laboratory for Micro Engineering Mekelweg 2 2628 CD Delft Netherlands

In this paper a short overview is given of the methods that are available for modelling the capacitance response of capacitive sensors. This includes the influence of alignment errors and electrode errors (geometrical errors and defects) as well as parasitic capacitances. Three methods are presented: direct calculation of the capacitance by solving the electric-field equations;approximation of the capacitance by simplifying the electric-field distribution;and modelling using the finite-element method. The suitability of each of these methods for different purposes is discussed. Conclusions are that in most cases approximations based on simplification of the electric field can be used to get an impression of the capacitance response, while for more complicated cases and for higher accuracy the more time-consuming finite-element method can or even must be used.

关键词： CAPACITIVE SENSORS finite-element modeling POSITION SENSORS

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finite-element modeling of the interaction of reinforcement with concrete matrix

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MECHANICS OF COMPOSITE MATERIALS 2008年第3期44卷 209-214页

作者： Pleskachevskii, Yu. M. Shimanovskii, A. O. Kuzemkina, G. M. Belarus State Transport Univ Gomel BELARUS

A finite-element model of a reinforced concrete beam with rebars modeled by a 3-D deformable body has been developed. An analysis of the stress-strain state of the beam allowed us to determine the stress distribution on cross sections of the rebars and the location of zones with cracks in concrete. It is found that the break of bond between the reinforcement and concrete goes outside the areas of intensely cracked concrete matrix.

关键词： concrete matrix reinforcement bond finite-element modeling stress-strain state

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finite-element modeling of the interaction of reinforcement with concrete matrix

Finite-element modeling of the interaction of reinforcement ...

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2nd Young Researchers Conference on FRP Reinforcement in Construction

作者： Pleskachevskii, Yu. M. Shimanovskii, A. O. Kuzemkina, G. M. Belarus State Transport Univ Gomel BELARUS

关键词： concrete matrix reinforcement bond finite-element modeling stress-strain state

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finite-element modeling of thermal performance for a novel water-cooled device used in switched mode power supply

Finite-element modeling of thermal performance for a novel w...

引用

4th International Power Electronics and Motion Control Conference (IPEMC 2004)

作者： Yu, XL Feng, Q Jiang, GB Xian Jiaotong Univ Xian 710049 Shanxi Peoples R China

ISBN: (纸本)7560518699

This paper describes a novel water-cooled device used to cool secondary coils of a group of transformers in a switched mode power supply used for electroplating. The device includes a vertically bended copper board, with which a U type tube is welded. This simple device mounted on each coil tap can remove heat from three heat sources including the secondary coil, a diode under the coil tap, and two electrical resistors connected to the diode. A 3-D finite-element modeling of thermal performance of the device is presented to simulate temperature distribution of the three heat sources when they work steadily. The corresponding experimental results coincide with the simulation results, which reveal that this device can satisfy cooling requirements of the three heat sources. It has advantages of simple structure, high heat rejection efficiency and low cost.

关键词： water-cooled device heat rejection finite-element modeling

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Experimental Study and finite-element modeling of the Intermittent Cutting of Steel AISI 52100 with a PcBN Containing Tool

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JOURNAL OF SUPERHARD MATERIALS 2023年第3期45卷 226-234页

作者： Teng, Fei Manokhin, A. S. Zhang, Junjie Klymenko, S. A. Sun, Tao Klymenko, S. An. Melniychuk, Y. O. Pasichny, O. O. Harbin Inst Technol Ctr Precis Engn Harbin 150001 Peoples R China Natl Acad Sci Ukraine Bakul Inst Superhard Mat UA-04074 Kiev Ukraine

Some results of experimental studies on the specific features inherent in the intermittent cutting of quenched steel AISI 52100 with a PcBN tool were presented, and the process of machining with a PcBN tool was analyzed by using the finite element method with consideration for the polycrystalline structure and composition of the tool. To ascertain the effect of the PcBN composite composition on the cutting forces and tool wear, experiments were conducted with cutters of two types of materials with different PcBN content. The obtained experimental results demonstrated the efficiency of the PcBN tool with a low PcBN content to be comparable with the tool characterized by a high PcBN content in the machining of quenched steel AISI 52100 at a cutting speed of 210 m/min under intermittent cutting conditions. The obtained results indicated the prospects and high performability of tools manufactured from PcBN composites of different composition under certain operational conditions.

关键词： PcBN tool cutting speed intermittent cutting finite-element modeling composition of PcBN composites

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An Efficient SQUID NDE Defect Detection Approach by Using an Adaptive finite-element modeling

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JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM 2011年第1-2期24卷 1077-1081页

作者： Sarreshtedari, Farrokh Razmkhah, Sasan Hosseini, Nahid Schubert, Jurgen Banzet, Marko Fardmanesh, Mehdi Sharif Univ Technol Dept Elect Engn Tehran Iran Forschungszentrum Julich Inst Bio & Nanosyst D-52425 Julich Germany

Incorporating the finite-element method for the modeling of the SQUID NDE response to a predefined defect pattern, an adaptive algorithm has been developed for the reconstruction of unknown defects using an optimization algorithm for updating of the forward problem. The defect reconstruction algorithm starts with an initial estimation for the defect pattern. Then the forward problem is solved and the obtained field pattern is compared with the measured signal from the SQUID NDE system. The result is used by an optimization algorithm to update the defect structure to be incorporated in the FEM forward problem for the next iteration. Since the mentioned model based inverse algorithm normally consumes a lot of computational resources, the number of iterations plays an important role in the determination of the total response convergence time. Consequently, different optimization algorithms have been applied and their performances are compared. In this work by incorporating an efficient forward model and using the stochastic and deterministic optimization algorithms for defect updating we have investigated their performance on the inversion of the SQUID NDE signal and also their ability to defect reconstruction in the noisy environment.

关键词： SQUID NDE Defect detection algorithm finite-element modeling

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Stress-Based Model for Lifetime Estimation of Bond Wire Contacts Using Power Cycling Tests and finite-element modeling

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IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS 2019年第3期7卷 1659-1667页

作者： Dornic, Nausicaa Khatir, Zoubir Son Ha Tran Ibrahim, Ali Lallemand, Richard Ousten, Jean-Pierre Ewanchuk, Jeffrey Mollov, Stefan, V French Inst Sci & Technol Transport Dev & Network SATIE Lab F-78000 Versailles France Mitsubishi Elect Res & Dev Ctr Europe MERCE F-35708 Rennes France

In this paper, a lifetime model for bond wire contacts of insulated gate bipolar transistors (IGBT) power modules is reported. This model is based on power cycling tests obtained under accelerated conditions, and a finite-element model taking into account the electrical, thermal, and mechanical coupling. It allows us to estimate the bond wire lifetime for a large scale of junction temperature swing amplitudes (Delta T-j) and stress durations (t(ON)). To build it, a numerical design of experiment was performed in both high and low stress values (Delta T-j). Then, a strain-life curve has been constructed where the average strain values on a defined volume around the contact areas between top-metallization and the most exposed bond wires to fatigue and liftoff have been used. As a result, it has been shown that the total strain is linearly dependent with Delta T-j and power law dependent with t(ON). The combination of the strain-life relation and the strain dependency with stress parameters leads to the lifetime relationship. The obtained lifetime model has been satisfactorily validated with some additional experimental points obtained from literature and with a large range of values for t(ON). This methodology can be easily replicated to other structures and is quite generic.

关键词： Accelerated aging finite-element modeling insulated-gate bipolar transistors (IGBT) junction temperature lifetime model power cycling power module strains stresses wire bonds

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