Coupled FEM Analysis Research Articles

Three-Dimensional Electromagnetic and Thermal Field Coupled Analysis of Different Types of REBCO Coils Under Overcurrent Conditions

The RE (rare earth) Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> (REBCO)-coated conductor has shown its high potential in various applications. However, the quench problem under overcurrent conditions, as well as some other problems, is still hindering its practical use. In this research, we have developed a versatile 3D electromagnetic and thermal field coupled FEM analysis tool for REBCO coils, and verified its capability in studying the transient electromagnetic and thermal behaviors, such as current density, Joule heating, temperature distribution, etc., with two case studies. In the first case study, the transient electromagnetic and thermal behaviors of SFCL REBCO coils under overcurrent are studied in the cases of uniform J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> distribution and local J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> degradation. The influence of current leads and local J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> degradation on the quench is investigated. In the second case study, the influence of external energy input, input area, and different time constants of current decrease on the quench of magnet REBCO coils is studied. Moreover, the limitation and improvement of the quench detection scheme based on voltage detection are discussed. The influence of external energy input on the current density distribution is also investigated.

ANALYSIS OF EMBANKMENT STRESS PRODUCED DURING CONSTRUCTION AND IN-SERVICE PHASES CONSIDERING EMBANKMENT GEOMETRIES

Soil compaction tests are carried out to improve embankment construction engineering characteristics, such as stability and deformation. For construction, enclosed embankment structures perform total strengthening and a measure of drainage functions. This provides stability, improves deformation properties, and prevents the degradation or rot of objects placed in the embankment fill. Nevertheless, chances are that inadequate compaction will cause material, such as rocks or stones, to fall from the slope surface, as well as erosion. Therefore, the standards for embankment slope steepness set forth the use of a 1:1.8 ratio, permissible on an as-needed basis to allow for mechanical rolling for compaction. When constructing steep embankment slopes, it is necessary to conduct embankment stability checks and fully consider the provision of slope protection to prevent erosion. However, differences in stress conditions attributable to varying slope steepness have not been elucidated. In this study analyzes embankment construction in terms of different construction seasons and slope change, using the unsaturated soil-water-air coupled FEM analysis program. In this way, more accurate qualitative evaluation could be achieved.

Numerical Analysis of the New Concept of Screw of an Extruder for Polymer Materials

The article introduces an innovative concept of a screw of an extruder used for granulation of polymer materials. Three construction solutions were introduced, differing in the construction parameters of the screw. The scope of the research included the numerical strength-thermal analysis of the introduced construction solutions of the screw. The analysis was conducted using the finite element method. Numerical calculations were a thermally coupled FEM analysis, posing a geometrically and thermally nonlinear problem. The obtained results confirmed the sufficient strength of the structure of the screw, subjected to both the pressure caused by the transport of polymer granules as well as the temperature generated by the friction of the granules on the surface of the screw. The numerical tool applied in the research was the commercial program ABAQUS®.

Three-Dimensional Thermal Analysis of an SFCL REBCO Coil Immersed in Liquid Nitrogen

A resistive type superconducting fault current limiter (SFCL) using REBCO tapes has shown its advantages in power applications. However, the hotspot problem, which can be caused by the uniformity of critical current density JC over long-length of REBCO tapes, is still a threat to the SFCL safety. In this paper, we have studied the limiting performance and transient temperature rise distribution of a nonintersecting type non-inductive solenoidal SFCL REBCO coil using three-dimensional electromagnetic and thermal coupled FEM analysis. Firstly, we modelled a local degradation of JC and studied its influence on the transient temperature rise distribution during the over current. The results indicated that a narrow and severe JC degradation leads to the concentration of current and heat generation in the normal JC area, which is opposite to the case of a relatively wider and slighter JC degradation area. Furthermore, REBCO tapes with different thickness of substrate and Ag over-layer were analysed to study the influence on limiting performance and temperature rise. A thicker substrate leaded to a slower temperature rise because of its higher heat capacity, and the Ag over-layer of 4 μm showed better limiting performance and thermal stability because of its better thermal conductivity as well as uniform temperature rise and SN transition.

3D thermomechanically coupled FEM analysis of large disk rolling process and trial production

Recently, rolling technique used to manufacture rings with various dimensions, shapes, and materials is innovated to a revolutionary technique for the fabrication of large disks. In this paper, in order to study the forming capability of this novel method, its principle was introduced, and the 3D thermomechanically coupled FE model was established using the dynamic explicit code ABAQUS/Explicit. Considering the adaptive treatment of boundary conditions, the user subroutines of ABAQUS were explored based on the movement law of the guide rolls and profiled axial rolls, and contacts between these rolls and the disk component. And the reliability of the FE model was verified theoretically and experimentally. Furthermore, the extending rule of plastic deformation zone and the effect of feed speed on the size of both the outer and inner diameters were investigated. The main results show that (1) the smallest equivalent plastic strain (PEEQ) occurs at the hub of the disk and the junction of the rim and the web, and the larger PEEQ appears on the outer surface of the rim and the web of disk. (2) Both the outer and inner diameters of the disk increase gradually at the beginning stage and more and more rapidly at a later stage. With the increase of the feed rate, the increase rate of both the outer diameter and inner diameter will decrease and the lateral spread rate will increase. And trial production of the large disk based on the analysis had been carried out successfully on the revamped Wagner RAW500/400 radial-axial ring rolling mill.

Thermal Coupled FEM Analysis of Precision Roll Forging Performing of Automobile Front Axle

According to the characters, technological condition and requirements of automotive front axle forging, both the process of exact roll-forging billet and die design are studied, as the result, roll- forging die of front axle billet, pre-completed roll-forging die and final roll-forging die are design respectively, finally the groove with hat cross-section is analyzed and top pressure rolling method is proposed during blank-making roll-forging process. The precision rolling forging performing deformation process of automobile front axle is simulated with finite element software Deform-3D by using 3D thermo-mechanical coupled rigid plastic FEM. The metal flow process, equivalent stress and strain field, temperature field and load status of rolling die are analyzed, and they are consistent with experiments. This provides a dependable theoretical basis for understanding the deforming mechanism and selecting reasonable parameters for the precision rolling forging performing of front axle.

The coupled FEM analysis of super-high angular speed polishing of diamond films

AbstractSuper-high angular speed polishing of diamond films is a new polishing method. During the polishing process, the rotational velocity of the cast iron polishing plate is higher than that of conventional polishing methods, and friction between the polishing plate and the diamond film during rotary motion generates heat that creates a diffusion condition for carbon atoms. The temperature and strain energy density distributions of the polished surface directly affect the polishing quality of diamond films. In this paper, a three-dimensional thermo-mechanical coupled finite element analysis was employed to analyze the temperature and strain energy due to the friction between the polishing plate and the thick diamond film while the polishing plate rotates at super-high angular speed. The results indicate that when the diamond film and polishing plate rotate in the same direction, the differences of temperature and strain energy evidently decrease, and the temperature and strain energy in the diamond film become more uniform. The removal rate by super-high speed polishing has been quantitatively described by the diffusion mechanism, and it agrees well with the experiment data. This work will provide theoretical guidance to the design and operation of the super-high speed polishing of diamond films.

The coupled fem analysis of the transient temperature field during inertia friction welding of GH4169 alloy

The inertia friction welding process is a non-linear process because of the interaction between the temperature field and the material properties as well as the friction force. A thermo-mechanical coupled finite element model is established to simulate the temperature field of this process. The transient temperature distribution during the inertia friction welding process of two similar workpieces of GH4169 alloy is calculated. The region of the circular cross-section of the workpiece is divided into a number of four-nodded isoparametric elements. In this model, the temperature dependent thermal properties, time dependent heat inputs, contact condition of welding interface, and deformation of the flash were considered. At the same time, the convection and radiation heat losses at the surface of the workpieces were also considered. A temperature data acquisition system was developed. The temperature at some position near the welding interface was measured using this system. The calculated temperature agrees well with the experimental data. The deformation of the flash and the factor affecting the temperature distribution at the welding interface are also discussed.

異形連続鋳造ビレットの鋳造過程におけるＦＥＭシミュレーション

Flow and solidification and thermal deformation coupled FEM analysis and casting experiment in the casting process of near net shaped billet semi-continuous casting were carried out in order to clarify the peculiar problems such as the surface crack and the phenomenon of the mould enclasped by shaped ingot during casting process. In this study, the flow and solidification analysis was calculated using a commercial solidification package CAPFLOW, and the thermal stress analysis was calculated by a structural analysis package ANSYS. The thermal histories from the CAPFLOW were used as input data to an elasto-plasticity model which simulated the thermal stress and deformation of the billet during the casting process. By comparing the calculated results with the experimental ones, the cause of the surface crack and the phenomenon of the mould enclasped by near net shape billet during casting process were clarified. It was proven that the surface crack of the near net shape billet originated from the force acted from the mould contacting with the billet, which is caused by the deformation of the solidification contracting. The phenomenon of the mould enclasped originated from the non-uniform deformation which arises by the non-uniform solidification in the billet cross section.

118 3 次元自動メッシュシステムを用いた筋-ヒフ連成表情解析

118 3 次元自動メッシュシステムを用いた筋-ヒフ連成表情解析

Numerical Simulation Method on Resistance Projection Welding Control Process

A coupled electrical field-circuit method was introduced to simulate the control process of electrical resistance welding. The circuit method was used to analyze the response of the control system and the field method was adopted to describe the behavior of the welding joint. By using a coupled electrical-thermal-mechanical FEM technology, the relationship of electrical, thermal and mechanical field was established. The coupled FEM analysis is adopted to analyze the behaviors of the welding joint. An equivalent circuit was introduced to combine the dynamic electrical resistance of workpieces, the welding power source and the control characteristics of the system. An updated method was selected to describe the dynamic response of the control system. In every increment, the variables were updated as initial conditions and boundary conditions in the field analysis, or resistance, voltage, current in the circuit analysis. An example was selected as projection welding process.