Articles de revues : « Equivalent Material Model »

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Jeon, Chi-Ho, Jae-Bin Lee, Sokanya Lon et Chang-Su Shim. « Equivalent material model of corroded prestressing steel strand ». Journal of Materials Research and Technology 8, n^o 2 (avril 2019) : 2450–60. http://dx.doi.org/10.1016/j.jmrt.2019.02.010.

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Alamayrekh, Yekaterina Yu. « Model of the decryption and model of the abbreviation formal diversity in the abbreviation group “auto-” ». Current Issues in Philology and Pedagogical Linguistics, n^o 2(2020) (25 juin 2020) : 91–102. http://dx.doi.org/10.29025/2079-6021-2020-2-91-102.

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The article deals with the principles of the analyses of the formal structure of the equivalence in the families of the equivalence of the compound abbreviations by the example of the abbreviation group “auto”. The relevance of the research is determined by the fact that on the basis of the synchronic equivalent approach to the description of the compound abbreviations a new interpretation of the characteristics of the formal equivalence of the word and correlated word-combination is described systematically. The results of this study provide a means of predicting the equivalence relations for the adjacent abbreviation clusters that is important while composing the techniques of making the dictionaries of a new type – explanatory dictionaries of abbreviations, the distinctive feature of which is the presentation of all equivalent word-combinations detected in the texts. The material for the study is formed by 252 families of equivalence which form the abbreviation group “auto” and contains 1621 abbreviation doubles: “compound abbreviation” – “equivalent word-combination”. The research was carried out on the basis of descriptive and quantitative methods as well as descriptive analyses and formalization. The author defines such notions as “compound abbreviation”, “decryption inducement”, “family of equivalence” as the basic categories of the synchronic approach to the abbreviation. The methods of synchronic analysis of the formal equivalence devised in the Laboratory are described: the analyses technique of the decryption inducement that designates the structural peculiarities of the decryption inducement – the stereotype of the decryption of compound abbreviation, and the analyses technique of the formal diversity of the equivalency that is a detached scheme of the combination of the components of the equivalent word-combination in the abbreviation. While development of the models of the decryption inducements the part of speech characteristics of the words forming the decryption inducements and their order in the equivalent word-combination are taken into account. While designing the models of formal equivalence that include the model of the equivalent word collocations and the abbreviation model, the correlation of the constructs of the correlated units, their peculiar grammatical features and the representation status in in words and word collocations are designated

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CAI, Lailiang, Kan WU, Qisheng YU et Jinpeng FENG. « A New Method of Equivalent Material Model Deformation Observation ». International Journal of Modern Education and Computer Science 3, n^o 5 (1 août 2011) : 40–46. http://dx.doi.org/10.5815/ijmecs.2011.05.06.

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Guo, Hongwei, Chuang Shi, Meng Li, Zongquan Deng et Rongqiang Liu. « Design and Dynamic Equivalent Modeling of Double-Layer Hoop Deployable Antenna ». International Journal of Aerospace Engineering 2018 (2018) : 1–15. http://dx.doi.org/10.1155/2018/2941981.

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This study proposes deployable units driven by elastic hinges and a double-layer hoop deployable antenna composed of these units. A rational modeling method based on the energy equivalence principle is presented to develop an equivalent model of the double-layer hoop antenna in accordance with the structural characteristics of the antenna. The equivalent beam models of the rods with elastic hinges are proposed. The relationship of geometrical and material parameters is established considering the strain energy and the kinetic energy of the periodic unit, which are the same as those of the equivalent beam in the same displacement field. The equivalent model of the antenna is obtained by assembling several equivalent beam models in the circumferential direction. The precision of the equivalent model of the antenna is acceptable as found by comparing the modal analysis results obtained through equivalent model calculation, finite element simulation, and modal test.

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Gyimóthy, Szabolcs. « Modeling stationary moving medium by static magneto-electric material ». European Physical Journal Applied Physics 85, n^o 1 (janvier 2019) : 10901. http://dx.doi.org/10.1051/epjap/2018180161.

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The electromagnetic equivalence of a stationary moving medium to magneto-electric materials is studied. The equivalent material characteristics of the medium at rest is obtained in terms of the diffusion tensor coefficient of the governing partial differential equation. Special attention is paid to the transition condition of field quantities on the boundary of the moving medium; it is found that the nonmoving magneto-electric equivalent model must be supplied with surface sources. The method is demonstrated through examples and verified by finite element simulation.

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Fan, Pengxian, Haozhe Xing, Linjian Ma, Kaifeng Jiang, Mingyang Wang, Zechen Yan et Xiang Fang. « Bulk Density Adjustment of Resin-Based Equivalent Material for Geomechanical Model Test ». Advances in Materials Science and Engineering 2015 (2015) : 1–8. http://dx.doi.org/10.1155/2015/363869.

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An equivalent material is of significance to the simulation of prototype rock in geomechanical model test. Researchers attempt to ensure that the bulk density of equivalent material is equal to that of prototype rock. In this work, barite sand was used to increase the bulk density of a resin-based equivalent material. The variation law of the bulk density was revealed in the simulation of a prototype rock of a different bulk density. Over 300 specimens were made for uniaxial compression test. Test results indicated that the substitution of quartz sand by barite sand had no apparent influence on the uniaxial compressive strength and elastic modulus of the specimens but can increase the bulk density, according to the proportional coarse aggregate content. An ideal linearity was found in the relationship between the barite sand substitution ratio and the bulk density. The relationship between the bulk density and the usage of coarse aggregate and barite sand was also presented. The test results provided an insight into the bulk density adjustment of resin-based equivalent materials.

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Zanelli, L., A. Montanaro, E. L. Carniel, P. G. Pavan et A. N. Natali. « The study of equivalent material parameters in a hyperelastic model ». International Journal of Non-Linear Mechanics 89 (mars 2017) : 142–50. http://dx.doi.org/10.1016/j.ijnonlinmec.2016.12.014.

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Garala, Thejesh Kumar, Ge Cui, Naman Kantesaria, Charles M. Heron, Alec M. Marshall et Lukáš Žižka. « Characterisation of spoil materials to develop an equivalent spoil material for physical model tests ». Górnictwo Odkrywkowe LXIII, n^o 4 (4 octobre 2022) : 23–29. http://dx.doi.org/10.5604/01.3001.0053.8055.

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The engineering behaviour of spoil (overburden) needs to be explored either to understand the stability of reservoir slopes under various geological and climatic conditions or for the effective utilisation of reclaimed mines for sustainable infrastructure (e.g., onshore wind turbines). The spoil material is usually considered as highly heterogeneous, and samples collected from the same site can exhibit widely varying characteristics. In this study, spoil material from a mine site in the Czech Republic is characterised using in-situ field tests and laboratory tests. Cone penetration tests were performed in the field and sample cores were collected for laboratory testing. In the laboratory, the index and engineering characteristics of the spoil were evaluated. Given the measured characteristics and behaviour of the field spoil, an equivalent spoil is proposed to perform physical modelling tests using geotechnical centrifuge. This enables simulation of the field spoil behaviour in controlled centrifuge testing, from which other aspects of spoil (e.g. stability of spoil slopes, spoil-structure interaction) can be investigated.

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Won Kim, Jae, Jae Ung Cho, Chan Ki Cho et Jin Oh Kim. « A study on damage to mechanical seat cushion made from different materials of extension frame ». International Journal of Engineering & ; Technology 7, n^o 3.3 (8 juin 2018) : 315. http://dx.doi.org/10.14419/ijet.v7i2.33.14176.

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Background/Objectives: : Automotive seat is a very important component to prevent accidents by reducing passenger’s tiredness, thus, this study worked on analyzing damage with different materials of extension frames of mechanical seat cushions.Methods/Statistical analysis: In this study, we performed an experiment on cushion extension frames by splitting it into two parts. We studied about the damage prediction of slave body for each material property of ABS, PP, PLA, and PA6.6. For analyzing the condition, we assigned the side part of the master body for fixed support, and we progressed on analysis by applying with 690N on the entire part of the slave body.Findings: This research worked on the study of damage to different materials of extension frames of seat cushions. After confirming the stress equivalence of the entire model for each material, PP showed the highest equivalent stress of 180.88MPa, and ABS showed the lowest equivalent stress of 151.73MPa. Overall, we could see that in the order of ABS, PA6.6, PLA, PP have a higher tendency to be broken. In addition, when confirming equivalent stress of master body depending on materials of slave body, PA6.6 showed the highest equivalent stress of 166.3MPa, and ABS showed the lowest equivalent stress of 124.06MPa. Overall, we could see that in the order of ABS, PP, PLA and PP6.6 have a higher tendency to be broken. In comparing shear stress on the gear part, which has the highest tendency to be broken in among the entire model, depending on the material of the slave body, PLA showed the greatest shear stress of 88.945MPa, and ABS showed the lowest shear stress of 69.766MPa.Improvements/Applications: This study worked for the improvements and applications of cushion extension frames as the securement of material by investigating these factors.

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Xian, Xiang Ping, Yan Shuai Wang, Feng Xing et Bi Qin Dong. « Measuring and Modeling Analysis of Electrochemical Impedance Spectroscopy for Hydration Procedure of Cement Materials ». Advanced Materials Research 588-589 (novembre 2012) : 1033–36. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.1033.

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In this paper, the electrochemical impedance spectroscopy method is applied to characteristic the hydration procedure in cement materials. And a new equivalent circuit model is developed to express the hydration procedure of cement material. As cement paste is a complicated electrochemical system with multi-phase transmission, the equivalent circuit model is considered with the additional double layer capacitance effect at the interface among the hydration products in cement materials. It can express the electrochemical station in cement material, as the multi-phase mass transmission in the cement-based material during the hydration procedure.

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Zhang, Zeyu, Zhiyong Jiao, Hongbing Xia et Yuhan Yao. « Parameter Equivalent Method of Stator Anisotropic Material Based on Modal Analysis ». Energies 12, n^o 22 (8 novembre 2019) : 4257. http://dx.doi.org/10.3390/en12224257.

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Accurate calculation of the vibration mode and natural frequency of a motor stator is the basis for reducing motor noise and vibration. However, the stator core and winding material parameters are difficult to determine, posing issues which result in modal calculation bias. To address the problem of calibrating the stator material parameters, we developed a parameter correction method based on modal frequency. First, the stator system was simplified to build a stator system finite element model. Secondly, the relationship between modal frequency and material parameters was analyzed by finite element software, the relationship between modal frequency and material parameters was derived, and the anisotropic material parameter correction method was summarized. Finally, a modal experiment was carried out by the hammering method, and the simulation and experimental errors were within 3%, which verified the accuracy of the finite element model. The proposed correction method of anisotropic material can quickly determine the stator material parameters, and the stator core and winding anisotropic material can ensure the accuracy of the modal analysis.

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Basov, V. V. « The Study of Geomechanical Condition of Unstable Rocks in the Vicinity of Mine Working Junctions ». Mining science and technology 4, n^o 1 (27 avril 2019) : 23–30. http://dx.doi.org/10.17073/2500-0632-2019-1-23-30.

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The relevance of research of material strain nature based on physical models equivalent to rocks is substantiated. To identify the dependencies and mechanism of unstable rock strain in the vicinity of mine working junctions, an experimental technique has been developed and presented. The method of physical modeling using equivalent materials was applied in the research. Strength characteristics of the rock equivalent material were calculated using the formulas proposed by G.N. Kuznetsov. The equivalent material was prepared based on two components, sand and paraffin. The mix formulation was selected, and ultimate compressive strength of the equivalent material was determined. The experiment was performed for three options of the physical models: an intact rock mass, a rock mass with a single mine working, and a rock mass with mine working junctions. Testing of the models made of the equivalent material was performed through uniaxial vertical loading using a hydraulic press. Based on the model testing findings, the dynamics of fracture propagation and crushing of the enclosing equivalent material in the vicinity of an artificial cavity, simulating a mine working, has been demonstrated. Besides, the graphs of relative strain versus vertical loading for each stage of the stepwise loading of these three model options were produced. The findings of the strain-stress distribution modeling for the equivalent material around the cavities simulating mine working junctions were analyzed. The strain testing findings for the materials simulating rock behavior are expected to be used as the initial data for analysis of physical and numerical simulation, as well as for developing engineering documentation with regard to the selection of parameters for supporting mine working junctions.

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Han, Renxiu, Guoxi Li, Jingzhong Gong, Meng Zhang et Kai Zhang. « Equivalent Method of Joint Interface Based on Persson Contact Theory : Virtual Material Method ». Materials 12, n^o 19 (26 septembre 2019) : 3150. http://dx.doi.org/10.3390/ma12193150.

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An accurate equivalent method of metal joint interface is of great significance to optimize the dynamic performance of the whole machine. Therefore, it is necessary to establish an accurate equivalent method of joint interface. The virtual material method is a precise equivalent method of joint interface. The traditional virtual material method is based on the M–B fractal contact theory. By modeling the contact mechanics of the joint interface, the physical properties of the virtual material are obtained separately, such as elastic modulus, Poisson’s ratio and density. In this paper, Persson contact theory is used to establish the interface contact mechanics model to find the physical properties of virtual materials. The virtual material methods constructed by two theories are respectively applied to the modal simulation to obtain the natural frequencies of the joint interface. By comparing the natural frequencies obtained by modal experiment and modal simulation, it is found that the natural frequencies obtained by the virtual material method based on Persson contact theory are closer to the results obtained by the modal experiment, and the error is within 5%. The error of the natural frequencies obtained by the virtual material method based on the M–B fractal contact theory is within 10%. Therefore, the Persson contact theory can establish a more accurate equivalent method of metal’s joint interface.

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Zilin, Yao, Wang Yu, Yang Xuefeng, Gao Anping, Zhang Rong et Jia Yanjie. « Investigations of Mechanical Properties of API P110 Steel Casing Tubes Operated in Deep-Sea Sour Condensate Well Conditions ». Polish Maritime Research 27, n^o 3 (1 septembre 2020) : 121–29. http://dx.doi.org/10.2478/pomr-2020-0053.

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AbstractDue to the complexity of the marine environment, in deep-sea drilling, all kinds of strings are corroded by different deep-sea conditions for a long time, accompanied by high temperature and high pressure, which lead to the continuous change of mechanical properties of materials. In order to solve the problem that the material mechanical parameters cannot be accurately described in the performance analysis of the casing, deep-sea simulated corrosion and material damage experiments of P110 material were carried out in this paper. Mass loss and tensile experiments on corrosion-damaged test pieces were conducted under different corrosion experimental periods. The changes in mechanical properties of the material were analyzed. Equations of the variation of the equivalent yield strength and the equivalent tensile strength were obtained. The results show that the equivalent yield strength and the equivalent tensile strength decrease with the increase of the weight loss rate. Based on the experimental results and finite element analysis, a method for establishing the material corrosion model was proposed in this paper. The deep-sea drilling corrosion performance model of P110 material was established, which greatly reduced the error caused by the material uniformity assumption in finite element analysis. This paper provides a theoretical basis for the analysis of reliability and life of P110 materials in wells.

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Çınar, Okan, Merve Erdal et Altan Kayran. « Accurate equivalent models of sandwich laminates with honeycomb core and composite face sheets via optimization involving modal behavior ». Journal of Sandwich Structures & ; Materials 19, n^o 2 (3 août 2016) : 139–66. http://dx.doi.org/10.1177/1099636215613934.

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An approach is introduced for determining accurate two-dimensional equivalent laminated models of sandwich laminates with honeycomb core and composite facesheets by optimization involving modal behavior. The approach relies on minimizing the objective function which is defined as the sum of the square of the differences between the natural frequencies of the honeycomb sandwich laminate estimated by the finite element analysis of the 3D detailed model with the actual honeycomb core geometry and by the 2D equivalent laminated model with the honeycomb core replaced by the equivalent 2D orthotropic material model. Equivalent elastic constants of the 2D orthotropic model of the honeycomb core are defined as the design variables of the optimization problem, and a finite element solver and genetic algorithm-based optimizer are coupled to perform the optimization task. Results show that with the optimization-based approach, very accurate 2D equivalent models of honeycomb sandwich laminates are obtained compared to equivalent models obtained by replacing the honeycomb core with elastic constants of the 2D orthotropic material model obtained utilizing analytical models available in the literature.

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Yan, Zhi Xin, Jian Duan, Ping Jiang et Hou Yu Wang. « A Study on Constitutive Model and Parameters of Rock Slope Stability ». Materials Science Forum 575-578 (avril 2008) : 1210–16. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1210.

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In this paper, taking elastic and plastic characteristics of rock into account, the authors have studied the relationship between different constitutive models. By transforming material parameters merely, on the basis of Equivalent Mohr-Coulomb Yield Criterion, the researchers achieved the application of these relationship in the computer program-Ansys5.7. They also have discussed the magnitude relationship between the transformed parameters and the original ones. By analyzing the cases of rock slope with obvious sliding surface, the researchers proved that it is liable to replace Mohr-Coulomb Yield Criterion with Equivalent Mohr-Coulomb Yield Criterion. We can use Equivalent Mohr-Coulomb Yield Criterion to simulate rock material, the results are smaller and more conservative than the standard ones. Meanwhile, the authors indicate that it is beneficial to apply Equivalent Mohr-Coulomb Yield Criterion to simulate rock material in rock slope projects with obvious sliding surface which have accurate standard requirements about displacement.

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Bin, Li, Liu Jianhui et Wang Xiuli. « A new multiaxial fatigue life prediction model considering additional hardening effect ». Advances in Mechanical Engineering 12, n^o 6 (juin 2020) : 168781402093533. http://dx.doi.org/10.1177/1687814020935331.

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The established linear fatigue life prediction model based on the Miner rule has been widely applied to fatigue life prediction under constant amplitude uniaxial and multiaxial loading. Considering the physical significance of crack formation and propagation, a multiaxial equivalent linear fatigue life prediction model is put forward based on Miner rule and critical plane method under constant amplitude loading. The essence of this approach is that the equivalent strain, which consists of the shear strain and normal strain on the critical plane, replaces the relevant parameter of uniaxial nonlinear fatigue damage model. The principal axes of stress/strain rotate under non-proportional loading. Meanwhile, the microstructure of material and slip systems change, which lead to additional hardening effect. The ratio of cyclic yield stress to static yield stress is used to represent the cyclic hardening capacity of material, and the influence of phase difference and loading condition on the non-proportional hardening effect is considered. The multiaxial fatigue life is predicted using equivalent stain approach, maximum shear stain amplitude model, CXH model, and equivalent multiaxial liner model under proportional and/or non-proportional loading. The smooth and notched fatigue specimens of four kinds of materials (Q235B steel, titanium alloy TC4, Haynes 188, and Mod.9Cr-1Mo steel) are used in the multiaxial fatigue experiments to verify the proposed model. The predicted results of these materials are compared with the test results, and the results show that these four models can achieve good effect under proportional loading, but the proposed model performs better than the other three models under non-proportional loading. Meanwhile, it also verifies that the proposed enhancement factor can reflect the influence of phase difference and material properties on additional hardening.

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Yang, Ming Bo, Jin Bao Chen, Fei Deng et Meng Chen. « Analysis of Buffering Properties of Honeycomb Material ». Advanced Materials Research 482-484 (février 2012) : 1146–49. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.1146.

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The buffering properties of honeycomb material are analyzed in the presented work. Theoretical analysis based on energy method is first presented, the buffering process of honeycomb material can be divided into three phases, honeycomb material can be equivalent to orthotropic material and the equivalent material properties are given. Being good at soil mechanics, Abaqus can simulate lunar soil very well. Using a constitutive model for honeycomb material, which is a built-in user material model, the presented work developed a honeycomb material simulation model and verified with a practical example. Now we can analysis the entire landing buffer process in Abaqus, which is a complement to existing analysis processes.

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Mohapatra, Kasinath Das, Susanta Kumar Sahoo et Munmun Bhaumik. « Thermal Modeling and Structural Analysis in Wire EDM Process for a 3D Model ». Applied Mechanics and Materials 852 (septembre 2016) : 279–89. http://dx.doi.org/10.4028/www.scientific.net/amm.852.279.

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Wire EDM is one of the most non conventional machining processes used for cutting of different types of complex materials. Copper material in wire EDM has a wide application in several industries but its thermal and structural analysis in wire EDM has challenged the authors to model the work-piece and tools accurately using the software. The present work deals with the design of a 3 dimensional model of a work-piece material made of copper. The objective of the present work is to analyse the temperature, total heat flux and equivalent stress of the work-piece material using finite element analysis in ANSYS software. In the current work, a 3D model was designed with the Steady state thermal analysis and it was designed with the available experimental data using ANSYS workbench. The temperature and the total heat flux were calculated using this analysis. Another analysis is performed using Static structural to calculate the equivalent stress generated in the work-piece material using ANSYS. The model was developed for single spark only. Automated type of meshing and axi-symmetric type of geometry are considered for this experiment. The wire part is neglected and all the analysis is made on the work-piece only. XRD analysis is also performed on the work-piece material to know the crystallinity of the compound. Mesh Convergence test was also performed to determine the optimum solution for the requisite mesh. Finally the model was designed and various graphs were plotted for the temperature, total heat flux and equivalent stress of the material.

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Zhang, Yiyang, Lei Duan, Genlin Wang, Ming Zhang et Zhiwei Luo. « A Prediction of Permittivity of Dielectric Elastomer using an Equivalent Capacitance Model and its Effect in Material Designing and Manufacturing ». Journal of the Institute of Industrial Applications Engineers 5, n^o 2 (25 avril 2017) : 100–103. http://dx.doi.org/10.12792/jiiae.5.100.

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SONG, SEUNG-HO, TAE-WAN KU, JEONG KIM, BEOM-SOO KANG et WOO-JIN SONG. « INVESTIGATION ON THE EQUIVALENT MATERIAL PROPERTY OF CARBON REINFORCED ALUMINUM LAMINATES ». International Journal of Modern Physics B 22, n^o 31n32 (30 décembre 2008) : 6149–54. http://dx.doi.org/10.1142/s0217979208051716.

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Fiber metal laminates as one of new hybrid materials with the bonded structure of thin metal sheets and fiber/epoxy layers have been developed for the last three decades. These kinds of materials can provide the characteristics of the excellent fatigue, impact and damage tolerance with a relatively low density. Because metal sheets and fiber/epoxy layers are bonded each other, the bonding between two materials is critical. In this study, the bonding strength is investigated experimentally with respect to surface roughness of metal sheets. The equivalent material properties of carbon reinforced aluminum laminates as the input data in the numerical simulation are also investigated and compared with the experimental result. The application of the equivalent material property to the numerical simulation can provide the high degree of efficiency in the build-up of the finite element model and the numerical simulation.

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Gao, Junjie, Haitao Han, Daiying Deng et Jijun Yu. « Mathematical Model for Analyzing Heat Transfer Characteristics of Ablative Thermal Insulating Material ». International Journal of Aerospace Engineering 2020 (8 juillet 2020) : 1–19. http://dx.doi.org/10.1155/2020/8817902.

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A mathematical model based on minimal thermal resistance and equal law of specific equivalent thermal conductivity is developed to discuss the heat transfer characteristics of ablative thermal insulating material from the mesoscopic scale. Based on the statistical results of mesoscopic parameters, the microstructure unit cell model was established to analyze the influence rule of mesoscopic parameterization which includes the size, distribution, and positional relation of microsphere and fiber. The results show that the equivalent thermal conductivity decreases with the density, size, distribution area, and distance of microsphere and the space distance and volume fraction of fiber decreasing. Besides, the equivalent thermal conductivity will become larger when more quality of heat transfers along the fiber direction. Exploring the relationship between the macroscopic heat transfer process and the microstructure is meaningful for exploring the heat transfer behavior of thermal insulating material and improvement of the processing technology.

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Shi, Kun, Guangpeng Zhang, Junping Shi et Qiang Gao. « Equivalent characteristic model of a rough contact interface based on virtual material method ». Advances in Mechanical Engineering 14, n^o 9 (septembre 2022) : 168781322211250. http://dx.doi.org/10.1177/16878132221125073.

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The characteristic of rough contact interface has a major influence on overall performance of machines. To facilitate the setting of contact interface characteristics during the performance analysis of the whole machine, an equivalent characteristic model of a rough contact interface based on virtual material method is established. The normal and tangential properties of the rough contact interface per unit area are first experimentally conducted. Furthermore, according to the Greenwood-Williamson (GW) model and stress wave propagation conditions of discrete elements, the relationship between normal and tangential contact characteristics is explored by assuming the rough contact interface per unit area as a thin virtual layer. Based on virtual material method, the equivalent characteristic model of a rough contact interface is established, including equivalent virtual elastic modulus, Poisson’s ratio, thickness, and density. Finally, taking two step-shaped steel plates connected by four bolts for example, a numerical simulation of structural characteristics under different preloads is carried out. Numerical analysis results are then compared with tested results to verify the validity of the equivalent virtual material model of rough contact interface, and a good agreement between them is obtained.

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Roy Mahapatra, D. « Equivalent constitutive model-based design of wave-absorbing material system and controller ». Journal of Sound and Vibration 289, n^o 3 (janvier 2006) : 509–28. http://dx.doi.org/10.1016/j.jsv.2005.02.011.

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Gao, Feng, Wen Miao Li et Ya Jun Hou. « Investigation for Mechanical Properties of Porous Materials Based on Homogenization Theory ». Advanced Materials Research 1048 (octobre 2014) : 414–17. http://dx.doi.org/10.4028/www.scientific.net/amr.1048.414.

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This paper investigated the macro-mechanical properties of three dimension porous materials consisted of periodically arrayed base units with random pore distribution using homogenization theory. The model of base unit using random numbers was established. A finite element method of homogenization equations was derived for the three dimension periodic structures and was applied to the calculation of the equivalent elastic modulus of porous materials with various porosities.The results shows the equivalent elastic modulus of three dimension porous material has significantly negative correlation with the porosity of material (p < 0.001) and the regression equation is E=(-19.4)ρ+17.6(E=equivalent elastic modulus, ρ=porosity ) when the elastic modulus of the solid matrix is 18 Gpa.

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Wu, Jun, Ruishan Yuan, Zhenwu He, Di Zhang et Yonghui Xie. « Experimental Study on Dry Friction Damping Characteristics of the Steam Turbine Blade Material with Nonconforming Contacts ». Advances in Materials Science and Engineering 2015 (2015) : 1–15. http://dx.doi.org/10.1155/2015/849253.

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An experiment system has been established to study the dry friction damping dynamic characteristics of the steam turbine blade material 1Cr13. The friction dynamic characteristics of the specimens with nonconforming contact surfaces are measured under different parameters. The experiment results are compared with that of the macroslip hysteresis model and the Mindlin microslip friction model in detail. The results show that the experimental result of the tangential contact stiffness is in good agreement with that of the theory result based on the fractal theory and the Hertz contact theory by Jiang et al., 2009. The dimensionless equivalent stiffness and equivalent damping obtained by the macroslip hysteresis model agree well with the experimental results when relative motion is relatively large. However, the results of the macroslip hysteresis model differ a lot from the experimental results when relative motion is relatively small. Compared with the macroslip hysteresis model, the Mindlin microslip friction model can predict the dimensionless equivalent stiffness and equivalent damping accurately during the whole measurement range. The linear regularities of dimensionless equivalent stiffness and equivalent damping are obtained, which decrease the difficulty of building the vibration analysis model of the blade with sufficient accuracy.

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Nazarenko, Lidiia, Henryk Stolarski et Holm Altenbach. « Modeling Cylindrical Inhomogeneity of Finite Length with Steigmann–Ogden Interface ». Technologies 8, n^o 4 (18 décembre 2020) : 78. http://dx.doi.org/10.3390/technologies8040078.

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A mathematical model employing the concept of energy-equivalent inhomogeneity is applied to analyze short cylindrical fiber composites with interfaces described by the Steigmann–Ogden material surface model. Real inhomogeneity consists of a cylindrical fiber of finite length, and its surface possessing different properties is replaced by a homogeneous, energy-equivalent cylinder. The properties of the energy-equivalent fiber, incorporating properties of the original fiber and its interface, are determined on the basis of Hill’s energy equivalence principle. Closed-form expressions for components of the stiffness tensor of equivalent fiber have been developed and, in the limit, shown to compare well with the results available in the literature for infinite fibers with the Steigmann–Ogden interface model. Dependence of those components on the radius, length of the cylindrical fiber, and surface parameters is included in these expressions. The effective stiffness tensor of the short-fiber composites with so-defined equivalent cylindrical fibers can be determined by any homogenization method developed without accounting for interface.

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Aleksandrov, Samuil R., Timo T. Overboom et Elena A. Lomonova. « 2D Hybrid Steady-State Magnetic Field Model for Linear Induction Motors ». Mathematical and Computational Applications 24, n^o 3 (25 juillet 2019) : 74. http://dx.doi.org/10.3390/mca24030074.

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This paper presents a 2D hybrid steady-state magnetic field model, capable of accurately modeling the electromagnetic behavior in a linear induction motor, including primary slotting, finite yoke length, and longitudinal end-effects by primary motion. This model integrates a complex harmonic modeling technique with a discretized magnetic equivalent circuit model. The Fourier model is applied to regions with homogeneous material properties, e.g., air regions and the track of the motor, while the magnetic equivalent circuit (MEC) approach is used for the regions containing non-homogeneous material properties, e.g., the primary of the linear induction motor (LIM). By only meshing the domains containing highly-permeable materials, the computational effort is reduced in comparison with the finite element method (FEM). The model is applied to a double-layer single-sided LIM, and the resulting thrust and normal forces show an excellent agreement with respect to finite element analysis and measurement data.

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Alwattar, Tahseen A., et Ahsan Mian. « Developing an Equivalent Solid Material Model for BCC Lattice Cell Structures Involving Vertical and Horizontal Struts ». Journal of Composites Science 4, n^o 2 (17 juin 2020) : 74. http://dx.doi.org/10.3390/jcs4020074.

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In this study, a body-centered cubic (BCC) lattice unit cell occupied inside a frame structure to create a so-called “InsideBCC” is considered. The equivalent quasi-isotropic properties required to describe the material behavior of the InsideBCC unit cell are equivalent Young’s modulus ( E e ) , equivalent shear modulus ( G e ) , and equivalent Poisson’s ratio ( ν e ) . The finite element analysis (FEA) based computational approach is used to simulate and calculate the mechanical responses of InsideBCC unit cell, which are the mechanical responses of the equivalent solid. Two separates finite element models are then developed for samples under compression: one with a 6 × 6 × 4 cell InsideBCC lattice cell structure (LCS) and one completely solid with equivalent solid properties obtained from a unit cell model. In addition, 6 × 6 × 4 cell specimens are fabricated on a fused deposition modeling (FDM) uPrint SEplus 3D printer using acrylonitrile butadiene styrene (ABS) material and tested experimentally under quasi-static compression load. Then, the results extracted from the finite element simulation of both the entire lattice and the equivalent solid models are compared with the experimental data. A good agreement between the experimental stress–strain behavior and that obtained from the FEA models is observed within the linear elastic limit.

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Pisareva, T. A., N. S. Shadrin, E. V. Kharanzhevskiy et S. M. Reshetnikov. « Model of supercapacitor electrodes based on nanostructured materials ». Physics and Chemistry of Materials Treatment, n^o 3 (2020) : 74–83. http://dx.doi.org/10.30791/0015-3214-2020-3-74-83.

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The substantiation of an extended model of the equivalent electric circuit of supercapacitor electrodes based on nanostructured materials taking into account the change in the characteristics of charge transport in the electrolyte–electrode material system at various frequencies depending on the thickness of the electrode material has been presented. The model is aimed at predicting the impedance characteristics of supercapacitors depending on the conductivity of the electrolyte, the characteristics of the pores, and the thickness of the nanostructured material of the electrode. Good agreement was obtained between the calculation results and experimental data. Within the framework of the model, the decrease in the specific electric capacity of supercapacitors with an increase in the thickness of the electrode material is explained by the significant influence of the relatively small values of the electrolyte resistance in the space between the powder particles and the contact resistance between the electrode material particles.

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Han, Renxiu, Guoxi Li, Jingzhong Gong, Meng Zhang et Kai Zhang. « Experimental Verification and Comparative Analysis of Equivalent Methods on Metal’s Fixed Joint Interface ». Materials 12, n^o 15 (26 juillet 2019) : 2381. http://dx.doi.org/10.3390/ma12152381.

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In order to effectively improve the dynamic characteristics of the fixed metal joint interface, it is important to establish a correct equivalent model of the metal joint interface. In this paper, three equivalent methods for simulating the metal joint interface are analyzed, including the virtual material method, spring damping method, finite element method, and verification by modal experiment. First, according to the contact mechanics model of the constructed metal joint interface, the physical properties of the three-dimensional models of the fixed joint interface are assigned in the ANSYS software. Then, three methods are used for the modal analysis and compared with a modal experiment. The results show that the modal shapes of the three theoretical methods are consistent with those of the experimental modes. The first five natural frequencies obtained by the virtual material method are closest to the experimental natural frequencies, and the errors are within 10%. The errors of the other two methods are between 9% and 39%. Therefore, the virtual material method is a better equivalent method of the metal joint interface.

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Wei, Y., C. L. Chow, H. E. Fang et M. K. Neilsen. « Characteristics of Creep Damage for 60 Sn-40 Pb Solder Material ». Journal of Electronic Packaging 123, n^o 3 (20 octobre 1999) : 278–83. http://dx.doi.org/10.1115/1.1372319.

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This paper presents a viscoplasticity model taking into account the effects of change in grain or phase size and damage on the characterization of creep damage in 60 Sn-40 Pb solder. Based on the theory of damage mechanics, a two-scalar damage model is developed for isotropic materials by introducing the free energy equivalence principle. The damage evolution equations are derived in terms of the damage energy release rates. In addition, a failure criterion is developed based on the postulation that a material element is said to have ruptured when the equivalent damage accumulated in the element reaches a critical value. The damage coupled viscoplasticity model is discretized and coded in a general-purpose finite element program known as ABAQUS through its user-defined material subroutine UMAT. To illustrate the application of the model, several example cases are introduced to analyze, both numerically and experimentally, the tensile creep behaviors of the material at three stress levels. The model is then applied to predict the deformation of a notched specimen under monotonic tension at room temperature (22°C). The results demonstrate that the proposed model can successfully predict the viscoplastic behavior of the solder material.

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Liu, Hui, Zhongliang Yang et Lianchun Long. « Mechanical Properties of Stretching-Bending Synergistic Lattice Materials ». Journal of Physics : Conference Series 2535, n^o 1 (1 juin 2023) : 012019. http://dx.doi.org/10.1088/1742-6596/2535/1/012019.

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Abstract Lattice materials are widely used in engineering structures as their potential for multifunctional applications. In this study, a body-centered cubic (BCC) stretching-bending synergistic lattice material is constructed based on the face-centered cubic with vertical struts (FCCZ) stretching configuration that has both stretching and bending deformation mechanisms. Finite element models and equivalent models are established to investigate the mechanical properties of the stretching-bending synergistic lattice material. The effect of the relative density of the frame unit cell is studied. The results show that the finite element model agrees well with the calculated results of the equivalent model. The stiffness of the stretching-bending synergistic lattice material is significantly increased with the increase of the relative density of the frame unit cell. The findings of this work provide a reference for predicting and optimizing the mechanical properties of the stretching-bending synergistic lattice materials.

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Kokulu, Nil, Seden Acun Özgünler, Fethiye Ecem Edis et Saniye Karaman Öztaş. « An LCIA-based model proposal for the selection of building interior finishing materials ». Heritage and Sustainable Development 6, n^o 1 (3 juin 2024) : 379–94. http://dx.doi.org/10.37868/hsd.v6i1.425.

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The increasing environmental impacts of buildings highlight conscious material selection as a pivotal aspect of sustainable building design. Most current life cycle impact assessment (LCIA) models on material selection focus on the main construction or insulation materials while often neglecting the environmental effects of finishing materials. Hence, this study seeks to present an LCIA-based model for selecting finishing materials based on their environmental impacts. Environmental Product Declaration (EPD) as a data source for the mandatory steps of LCIA is recommended for the model since it provides fast, reliable, and equivalent data on the environmental impacts of the materials. The model is validated by assessing three wall finishing materials in hotel bedrooms- gypsum board, paint, and wood panel. Findings revealed that the model has the potential to mitigate the environmental effects by guiding decisions made during the finishing material selection phase.

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Fossum, A. F. « Rate Data and Material Model Parameter Estimation ». Journal of Engineering Materials and Technology 120, n^o 1 (1 janvier 1998) : 7–12. http://dx.doi.org/10.1115/1.2806842.

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Traditionally stress-strain data are used to estimate material parameters in viscoplastic material models. Since the models exist in rate form, they must be integrated in time for the duration of the laboratory tests to give response models for parameter estimation. In this paper the alternative is considered in which the rate form of the material models is fitted to time differentiated stress strain data. Material parameteres, their 95 percent confidence intervals, and their correlation coefficients are compared with their counterparts determined from the more traditional stress versus strain form of the data. It was found that the use of the stress rate form of the data gave well determined parameter estimates with equivalent or superior fitting statistics to the same data can be used to extract significant and distinct sensitivity coefficients to enchance the overall robustness of an optimization algorithm for a parameter estimation.

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Liu, Xi Liang, Hong Yu Liu et Xian Jun Han. « The Theory and Stability Studies on Composite Bolted Rock Mass ». Applied Mechanics and Materials 90-93 (septembre 2011) : 2131–37. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.2131.

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Firstly, This paper applied the basic principle of composite material mechanics, saw the rock mass, anchor, mortar as a kind of composite material, established micromechanics equivalent model of bolted rock mass, deduced corresponding parameters formula of bolted rock mass equivalent mechanical model. Secondly, we analyzed engineering example by using the finite element software, conducted a numerical simulation research on composite model and discrete roadway model based on the theoretical derivation. Finally, we verified the feasibility and applicability of the equivalent method by comparative analysis on two sides and roof-floor displacement of roadway and surrounding stress of rock. Thus, this paper established a simplified equivalent calculation method accord with the stability analysis of bolting and shotcreting support and the overall assess of support parameters.

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Kisel', Yuriy, Alexey Ulyanov et Viktor Kamynin. « IMPROVING THE METHODS FOR CALCULATING ELASTIC CHARACTERISTICS OF FIBRE COMPOSITES ». Automation and modeling in design and management, n^o 1 (17 mars 2022) : 15–23. http://dx.doi.org/10.30987/2658-6436-2022-1-15-23.

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Applying solid-state modelling methods for calculating the elastic properties and stress-strain state of fibre-reinforced composite materials is shown. A model of a composite material including a base and fibres is developed. The elastic properties and equivalent stresses in a fibrous composite material with different fibre content are determined.

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Haryanto, Ismoyo, Reni Reni et Achmad Widodo. « Pengembangan Equivalent Plate Model Guna Analisis Dinamis Struktur Wing-Box dengan Material Komposit ». ROTASI 19, n^o 4 (3 novembre 2017) : 243. http://dx.doi.org/10.14710/rotasi.19.4.243-251.

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Pada penelitian ini analisis getaran bebas dilakukan pada struktur wing-box yang dibuat menggunakan material komposit. Analisis yang didasrkan pada Equivalent-plate model dengan first-order shear deformation theory berdasarkan Reissner-Mindlin dilakukan untuk mendapatkan frekuensi pribadi dan modus getar dari struktur sayap pesawat udara tersebut. Pada studi ini wing-box yang ditinjau dimodelkan terdiri dari laminat yang tidak simetris. Persamaan gerak diturunkan dari Persamaan Lagrange untuk getaran bebas. Validasi dilakukan pada hasil analisa terhadap data yang diperoleh pada literatur. Hasil validasi menunjukkan kesesuaian antara hasil analisa yang dilakukan terhadap data pada literatur

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Yu, Jiaao, Shirui Peng, Hao Nan et Jianhao Liu. « Equivalent circuit model of an ultra-wideband frequency selective surface composite absorbing material ». Journal of Engineering 2019, n^o 19 (1 octobre 2019) : 5922–26. http://dx.doi.org/10.1049/joe.2019.0220.

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Wajnert, Dawid, et Bronislaw Tomczuk. « Nonlinear magnetic equivalent circuit of the hybrid magnetic bearing ». COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, n^o 4 (1 juillet 2019) : 1190–203. http://dx.doi.org/10.1108/compel-10-2018-0423.

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Purpose The purpose of this paper is to create a reliable nonlinear magnetic equivalent circuit (NMEC) of the hybrid magnetic bearing (HMB). Commonly used magnetic equivalent circuits of HMB omit a saturation effect of the magnetic material as well as the leakage and fringing flux. It results in imprecise modelling of the magnetic field distribution. On the other hand, only 3D finite element analysis (FEA) can be used to precisely simulate the magnetic field in this type of the magnetic bearing. The proposed NMEC incorporates the saturation effect of the magnetic material, as well as the leakage and fringing flux. Design/methodology/approach The magnetic equivalent circuit of presented HMB is proposed to obtain a reliable model that ensures short calculation time. Developed NMEC incorporates the phenomena as the saturation effect, as well as the leakage and fringing flux. The reluctance of the air gap that includes the fringing flux was calculated using 3D FEA. Kirchhoffs’ laws were used to create a set of nonlinear equations that were iteratively solved by Broyden’s method. Findings Incorporating into NMEC of the HMB a saturation effect of the magnetic material, as well as the leakage and fringing flux, resulted in the accurate model that was in good agreement with 3 D finite element model and the real object. The developed NMEC offers the calculation time in the range of miliseconds, therefore can be successfully used in the engineering design instead of the FEM. Originality/value Presented NMEC can be considered as a fundamental model that can be successfully used for accurate and fast simulation of the HMB. Proposed NMEC includes considerable factors that decide about the model accuracy such as the saturation effect of the ferromagnetic material and the leakage and fringing flux. The developed NMEC can be used in the optimization procedures and for simulations of dynamic responses.

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Jiang, Dong, Minrui Wang, Yuhang Sun et Xiaochen Hang. « Equivalent Modeling of Bolted Connections under Transverse Load Using Iwan-Based Material Properties ». Metals 13, n^o 1 (1 janvier 2023) : 91. http://dx.doi.org/10.3390/met13010091.

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The nonlinear characteristics of bolted connections are of significant importance for analyzing the mechanical performance of structures. The Iwan model is well-known and has been widely applied; its limitation is that it is not convenient for complex structures with multiple bolted connections. To simplify the modeling process, a material with the force-displacement characteristics of the Iwan model is proposed and applied to the bolted connection region, which can convert the nonlinearity of the bolted connection into the nonlinearity of the material. The constitutive relation of the proposed Iwan-based material is determined by the force-displacement equation of the bolted connection under load and the elastic-plastic hypothesis. The proposed Iwan-based material is implemented using the UMAT subroutine of ABAQUS, and the properties of the Iwan-based material are assigned to a solid finite element for an equivalent modeling of bolted connections. Through comparisons with the s imul ation results of the AIBE, the feasibility of the equivalent modeling method for the force-displacement relationship of the original Iwan model is verified, and through comparisons with the simulation results and experimental results of a detailed 3D FE model of the bolted connection, the universality of the equivalent modeling method is verified. The results show that the equivalent modeling method can well restore the statics characteristics of bolted structures under cyclic loading and can be applied to complex combined structures. The method is more convenient for establishing the finite element model of bolted connections and has more flexibility in adjusting parameters than traditional methods.

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Sun, Xiaoting, Yi Wang, Jinli Che et Wei Wang. « Theoretical study on cushioning isolation of cushioning materials under high impact environment ». Journal of Physics : Conference Series 2891, n^o 4 (1 décembre 2024) : 042006. https://doi.org/10.1088/1742-6596/2891/4/042006.

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Abstract When a guided projectile is fired, the high pressure generated by the gunpowder gas in the chamber produces a high impact accelerationtion of tens of thousands of g in the projectile, which makes the components of the projectile withstand a huge instantaneous, high-energy, strong impact load. This type of load environment results in the deformation and failure of the internal mechanical components and damage to all type of electronic components, leading to the failure of the entire guidance system. Selecting the correct cushioning material to store or dissipate the impact energy so that the peak value of the impact is reduced to within the range of the component is an effective technical approach. In this study, a mechanical analysis of the high-impact environment inside a certain type of artillery was conducted, the axial impact load variation curve of the projectile was drawn, and a buffer isolation mathematical model of the buffer material was established. This study obtains a visualization interface using Python to solve the problem intelligently. By changing the mass of the mass block, the equivalent stiffness and equivalent damping value of the buffer material in the program script, researchers can use the model to draw the displacement, velocity and acceleration curves of the two mass blocks simultaneously, and obtain the buffering efficiency and maximum elastic compression of the buffer material. When the equivalent damping is the same, this study obtains the buffering efficiency curve and the maximum elastic compression curve changing with the stiffness through the model. The results show that in the range of elastic deformation, the buffering efficiency is proportional to the length of the buffering material but inversely proportional to its equivalent stiffness. The mathematical model provides technical support for the pre-design development and selection of cushioning materials in high-impact environments.

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Zhou, Zhen Yu, et Qi Wen Xue. « Research on Homogenization of Composite Materials ». Advanced Materials Research 663 (février 2013) : 426–30. http://dx.doi.org/10.4028/www.scientific.net/amr.663.426.

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A numerical model is given to identify equivalent parameters of composite materials, using BP neural network algorithm. Taking Filament-wound composite pressure vessels as the research object, finite element models are first constructed .Getting node displacements as network training samples, the mechanical parameters as output information of network for effective training, the equivalent material parameters can be obtained. The satisfactory numerical validation is given and results show that the proposed method can identify the equivalent modulus and the equivalent Poisson’s ratio of the Filament-wound composite pressure vessels with precision. The computational efficiency is improved with BP neural network.

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Wang, Lian Bao, Xiao Qiu Hu et Wei Fu Chen. « Dynamic Parameters Equivalent Modeling of Bearings Joint Surfaces Based on the Virtual Material ». Applied Mechanics and Materials 433-435 (octobre 2013) : 35–39. http://dx.doi.org/10.4028/www.scientific.net/amm.433-435.35.

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As commonly supporting parts of the spindle and the feed systems on the high-end grade CNC machine tool, dynamic characteristic of angular contact ball bearings had been a research hot spot in the current. Aiming at solving the problem that obtained the dynamic stiffness and damping of angular contact ball bearings, the factors of joint surfaces dynamic characteristic were equivalently viewed as a kind of virtual material in the paper, and an equivalent model of dynamic parameters for bearings joint surfaces was proposed based on the virtual material; an experimental device was developed to test the bearings dynamic parameters. The comparison of experimental results and simulation results showed that modal parameters of bearings could be accurately analyzed by the proposed modeling approach, and the relative errors of corresponding vibration frequencies in the radial and the axial directions could be controlled within 7%.

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Kojic´, M., N. Grujovic´, R. Slavkovic´ et M. Zˇivkovic´. « A General Orthotropic von Mises Plasticity Material Model With Mixed Hardening : Model Definition and Implicit Stress Integration Procedure ». Journal of Applied Mechanics 63, n^o 2 (1 juin 1996) : 376–82. http://dx.doi.org/10.1115/1.2788875.

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A general orthotropic von Mises plasticity model, with an extension of the Hill’s yield criterion to include mixed hardening, is introduced in the paper. Material constants and equivalent stress-equivalent plastic strain curves are defined in a way to suggest their experimental determination. The model represents a special case of a general anisotropic metal plasticity model proposed by the authors. An implicit stress integration procedure, representing an application of the governing parameter method (GPM) introduced by the first author, is presented. The GPM is briefly described, and the computational procedure, together with calculation of the consistent tangent moduli, are given in some detail for a general three-dimensional deformation, with direction of application to plane stress/shell conditions. Numerical examples illustrate applicability of the model and effectiveness of the computational algorithm.

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Kara, Okan, et Hasan Hüseyin Çelik. « A Novel Nonlinear Magnetic Equivalent Circuit Model for Magnetic Flux Leakage System ». Applied Sciences 14, n^o 10 (10 mai 2024) : 4071. http://dx.doi.org/10.3390/app14104071.

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To ensure efficient inspection using the magnetic flux leakage (MFL) method, generating a flux density near the saturation level within the tested material is essential. This requirement brings high flux density conditions in the system’s pole regions. Hence, leakage flux within the slot is excessively triggered, leading to distortion of the defect signal. In this context, the system dimensions stand out as one of the most significant factors affecting the mentioned flux distributions. Therefore, various alternative solutions with different system dimensions arise in the design process of the MFL system. This study proposes a magnetic equivalent circuit (MEC) model to achieve optimal system design. The proposed MEC model is designed considering the nonlinear behavior of the material, leakage flux, and fringing effects. Verification results demonstrate that the MEC model consistently tracks the finite element analysis (FEA) results in calculating the flux densities. Furthermore, the relative errors in the flux density calculations of the tested material are at a maximum level of 10.2% and an average of 5.2% compared to the FEA. These findings indicate that the proposed MEC model can be effectively utilized in rapid prototyping and optimization procedures of MFL system design by providing fast solutions with reasonable accuracy.

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Li, Zhiheng, Shaoxiang Ma, Yongmao Wang, Bangyou Zhu, Hongqi Zhang, Ming Zhang, Yuan Pan et Kexun Yu. « Research and Analysis of Equivalent Circuit Model for Core Snubber ». Journal of Physics : Conference Series 2452, n^o 1 (1 mars 2023) : 012031. http://dx.doi.org/10.1088/1742-6596/2452/1/012031.

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Abstract The ion source is the key to the NBI. It is very sensitive to overvoltage and overcurrent, and the breakdown frequently occurs between the acceleration grid. The core snubber is the most suitable surge suppression device to achieve DC fault protection. This paper introduces some basic concepts, comparing the core snubber’s material properties and important parameters. It also introduces the basic concept of an equivalent circuit model for snubber, including the derivation process and theoretical analysis. Then the characteristics of the snubber and surge suppression analysis are introduced. Finally, this paper looks forward to the future research direction of the snubber.

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Kamm, Jochen, Michael Becken et Rafael Abreu. « Electromagnetic modelling with topography on regular grids with equivalent materials ». Geophysical Journal International 220, n^o 3 (13 décembre 2019) : 2021–38. http://dx.doi.org/10.1093/gji/ggz563.

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SUMMARY Maxwell’s equations are valid regardless of the choice of the coordinate system. By this property a change of coordinates can be equivalently expressed as a change of the material parameters. This idea opens a new approach to the problem of accurate electromagnetic modelling in the vicinity of steep topography or bathymetry. Via a change of coordinates, any earth model with complicated layer interfaces can be represented by an equivalent model where those interfaces are flat, but with its materials correspondingly altered. This new model could then be discretized on a regular mesh and fields could be computed by an appropriate finite difference or integral equation code. Unfortunately, this is not straightforward because both the new electric and magnetic materials are fully anisotropic. By instead applying a finite element secondary field approach to the equivalent model, we can completely account for the topography interface in the planar layered background model. The only modification required to existing finite element formulations is a slightly more complicated right-hand side of the linear system of equations, whereas the system matrix is unchanged in any coordinate system. In a numerical modelling experiment we confirm that our technique gives increased accuracy when compared with a recently published technique for dealing with topography in a secondary field formulation for the case of a magnetotelluric source field. In turn, in the vicinity of conductivity anomalies, accuracy can also be negatively affected.

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Das, S., et S. Chakraborty. « Damage Detection of FRP Composite Plates from Dynamical Responses using Finite Element Model Updating : Equivalent Material Properties as Parameters ». Proceedings of the 12th Structural Engineering Convention, SEC 2022 : Themes 1-2 1, n^o 1 (19 décembre 2022) : 1013–17. http://dx.doi.org/10.38208/acp.v1.614.

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Fibre reinforced plastic (FRP) composite structures are extensively used in weight sensitive applications, such as in aircrafts, ships, etc. Such structures are susceptible to damages during their usual operation or during extreme loading from environment. Due to the anisotropic nature of FRP composite plates, damage detection is difficult for such layered materials particularly when the damage site is inaccessible. The localised loss of stiffness resulting from damage is reflected into the global dynamic responses of such structures. Finite element model updating is a convenient inverse approach in which these changes in stiffness due to damages are estimated from measured dynamical responses using optimization. The equivalent stiffness changes can be expressed in terms of either geometric or material property or both. In most of the cases, changes in geometric parameters physically represent the actual damage scenario with larger sensitivity. On the other hand, material property changes in the damaged area are a very convenient parameter to deal with. In the present work, updating parameters in the finite element model updating procedure are chosen in terms of material property. Detection of local stiffness changes from experimentally measured natural frequencies, mode shapes and/or frequency response functions are investigated. Experimental modal testing is performed on a rectangular FRP composite plate both in its undamaged and damaged state. Baseline finite element model of the composite plate is correlated with experimental model, followed by a sensitivity based finite element model updating algorithm. The results show the rapid convergence and accurate determination of local stiffness change in terms of elastic material parameters alone in all three orthogonal directions. This indicates that material properties like the in-plane Young’s moduli and in-plane Shear modulus within the localised region of damage, can well be used as convenient means for detecting equivalent stiffness loss in damaged structures.

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Xia, Huanxiong, Junfeng Meng, Jianhua Liu, Xiaohui Ao, Shengxiang Lin et Ye Yang. « Evaluation of the Equivalent Mechanical Properties of Lattice Structures Based on the Finite Element Method ». Materials 15, n^o 9 (20 avril 2022) : 2993. http://dx.doi.org/10.3390/ma15092993.

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Lattice structures have excellent mechanical properties and can be designed by changing the cellular structure. However, the computing scale is extremely large to directly analyze a large-size structure containing a huge number of lattice cells. Evaluating the equivalent mechanical properties instead of the complex geometry of such lattice cells is a feasible way to deal with this problem. This paper aims to propose a series of formulas, including critical structural and material parameters, to fast evaluate the equivalent mechanical properties of lattice structures. A reduced-order model based on the finite element method and beam theory was developed and verified by comparing it with the corresponding full model. This model was then applied to evaluate the equivalent mechanical properties of 25 types of lattice cells. The effects of the material Young’s modulus and Poisson’s ratio, strut diameter, cell size, and cell number on those equivalent mechanical properties were investigated and discussed, and the linear relationship with the material parameters and the non-linear relationship with the structural parameters were found. Finally, a series of analytical-fitting formulas involving the structural and material parameters were obtained, which allows us to fast predict the equivalent mechanical properties of the lattice cells.

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