ADINA官网新增功能（电磁）和例子
本帖最后由 wry618 于 2011-3-1 20:56 编辑http://www.adina.com/htechbriefs.gif http://www.adina.com/em-movie.gif Electromagnetics with ADINA Electromagnetics is a very important area in science and engineering, especially when the electromagnetic effects are coupled with mechanical and fluid flow systems. There are many important applications: electric motors, heating of furnaces/ovens, medical procedures, electromagnetic switches, electromagnetic pumps or brakes, wave guides, antennas, transmission lines, electromagnetic casting, non-destructive testing of metals, and so on. All these electromagnetic phenomena and applications are uniformly governed by the general Maxwell's equations. For our multiphysics applications, we have therefore worked for some time to develop in the ADINA system a new modeling capability — the program ADINA-EM — to solve the general Maxwell's equations with different loading and boundary conditions. With the exciting new features provided by ADINA-EM, the ADINA users can now solve the general Maxwell’s equations for many different problems and also couple the electromagnetic effects with fluid flows. Fundamentally, the original first-order Maxwell’s equations governing electromagnetics for the electric field intensity http://www.adina.com/em_eq1.gif and the magnetic field intensity http://www.adina.com/em_eq2.gif are, see Ref. , http://www.adina.com/em_eq3.gif with http://www.adina.com/em_eq4.gif Also, the Maxwell’s equations in the frequency domain (for harmonic analysis) are http://www.adina.com/em_eq5.gif where http://www.adina.com/em_eq6.gif In these equations, the electromagnetic material is characterized by http://www.adina.com/em_eq7.gif, that is, the electric permittivity, magnetic permeability, and electric conductivity,respectively. The source terms are the two densities http://www.adina.com/em_eq8a.gif and http://www.adina.com/em_eq8b.gif, and the electric charge density http://www.adina.com/em_eq9.gif.Together with appropriate boundary conditions, Maxwell's equations uniquely determine http://www.adina.com/em_eq1.gif and http://www.adina.com/em_eq2.gif in the problem domain. In ADINA-EM, two distinctly different formulations, namely a novel http://www.adina.com/em_eq10.gif formulation and an http://www.adina.com/em_eq11.gif formulation are used, where in the http://www.adina.com/em_eq11.gif formulation as usual we use http://www.adina.com/em_eq12.gif For both formulations we utilize the finite element method. For efficiency and accuracy, instead of solving the first-order Maxwell's equations, given above, we have reformulated these equations to second-order relations, but without adding additional equations, see Ref. . It is important to note that we offer in ADINA-EM the two distinct formulations, that is, the http://www.adina.com/em_eq10.gif formulation and the http://www.adina.com/em_eq11.gif formulation. The reason is that the http://www.adina.com/em_eq11.gif formulation is familiar to engineers and scientists and can therefore directly be used — but has the well-known disadvantages. The http://www.adina.com/em_eq10.gif formulation is novel, it uses the physical variables as unknowns, is more direct and these variables can directly be coupled to the actions of fluids and solids. We should note as well that we do not use edge-type elements (with degrees of freedom at the element edges) but we use a more powerful formulation where — also — the finite element degrees of freedom directly couple to the usual fluid and solid elements used. The details of the formulation are presented in Ref. . With our first release of ADINA-EM, the following types of electromagnetic problems can be solved: ▪ Electrostatic fields▪ Magnetostatic fields▪ DC conduction▪ Time-harmonic▪ Eddy current▪ AC conduction▪ EM fields with Lorentz forces▪ EM fields coupled with temperature▪ Wave guideOf course, the pre- and post-processing for the ADINA-EM models and solutions are performed using the ADINA User Interface. Below we show the solutions of three example problems solved using ADINA-EM. Sharp material interface in harmonic analysis In this first example — which is a good verification problem — we demonstrate the capability of ADINA-EM in the calculation of electric and magnetic fields across a sharp material interface, with very different electromagnetic materials in the domains on each side. As shown in Figure 1, the material of the outside domain has zero conductivity while that of the inside domain has a very high conductivity. Because of these very different materials, the electric and magnetic fields have sharp variations across the material interface. Instead of using different formulations in the different domains, the problem is solved using ADINA-EM with the http://www.adina.com/em_eq10.gif formulation for both domains. The plots in Figures 2 and 3 show the real and imaginary parts of the electric and magnetic field intensities.
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Figure 1Sharp interface problem: schematic
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Figure 2Sharp interface problem: vector plot of http://www.adina.com/em_eq1.gif; real part (left) and imaginary part (right)
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Figure 3Sharp interface problem: band plot of http://www.adina.com/em_eq2.gif; real part (left) and imaginary part (right)
We also compare the results obtained using ADINA-EM with analytical results in Figures 4 and 5. The computational results agree closely with the theoretical values.
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Figure 4Sharp interface problem: http://www.adina.com/em_eq1.gif, results from ADINA compared to analytical results; real part (left) and imaginary part (right)
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Figure 5Sharp interface problem: http://www.adina.com/em_eq2.gif, results from ADINA compared to analytical results; real part (left) and imaginary part (right)
Electromagnetically induced mixing of glass melt in a pipe This is a multiphysics electromagnetic stirring and mixing problem. The ADINA-EM http://www.adina.com/em_eq11.gif formulation and the ADINA CFD formulation are used, coupled, to simulate the advective mixing in an electromagnetically-driven pipe mixer. The schematic of this problem is as shown in Figure 6 below. In this example, fluid flows in a cylindrical tube subjected to stirring and mixing by the Lorentz force generated by time-dependent voltages in two electrodes that are immersed in the conducting fluid, with the entire assembly in an otherwise externally imposed constant magnetic field. Stirring and mixing occur in the plane perpendicular to the flow direction due to the Lorentz force in that plane.
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Figure 6Electromagnetically induced mixing: schematic
The movie at the top shows the transient process of the mixing, starting from an inhomogeneous concentration at the inlet. In Figures 7 to 9 below, we present a steady-state solution of the electromagnetic mixing process, showing the calculated potentials http://www.adina.com/em_eq11a.gif and http://www.adina.com/em_eq11b.gif, the velocity in a plane perpendicular to the main flow direction, and the mass concentrations at the inlet and outlet. The homogeneous concentration at the outlet shows the perfect mixing achieved.
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Figure 7Electromagnetically induced mixing: Plot of http://www.adina.com/em_eq11a.gif (left) and http://www.adina.com/em_eq11b.gif (right)
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Figure 8Electromagnetically (chaotic) induced mixing: velocity vector plot near inlet
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Figure 9Electromagnetically induced mixing: mass ratio at inlet (left) and outlet (right)
Eddy current in a torus with cracks, induced by time-harmonic magnetic field A schematic of this problem is shown in Figure 10 below. An eddy current is induced in a conductor by an externally imposed harmonic magnetic flux. The toroid conductor has four cracks through its depth. These cracks modify the electric and magnetic fields that would normally result were there no cracks, and this observation is the basis of non-destructive testing (NDT) using electromagnetics. Only one eighth of the whole domain is modeled. This 3D time-harmonic eddy current problem is solved using the ADINA-EM http://www.adina.com/em_eq10.gif formulation. We show, in Figures 11 and 12 below, the band plots of the real and imaginary parts of the electric and magnetic field intensities. It can be seen that the cracks indeed change the direction and magnitude of both fields.
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Figure 10Eddy current in torus: schematic
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Figure 11Eddy current in torus: vector plot of http://www.adina.com/em_eq1.gif; real part (left) and imaginary part (right)
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Figure 12Eddy current in torus: plot of http://www.adina.com/em_eq2.gif; real part (left) and imaginary part (right)
Additional applications will be given in future briefs on ADINA-EM. Clearly, the addition of ADINA-EM to the ADINA system greatly extends and enhances the multiphysics capabilities offered in ADINA. The multiphysics capabilities can now be even more generally applied than before, with all the already existing powerful capabilities in ADINA, see here. References [*]C. A. Balanis, Advanced Engineering Electromagnetics, John Wiley & Sons, New York, 1989.[*]K. J. Bathe et al., The Direct Solution of Maxwell’s Equations in Multiphysics, in preparation.
Keywords:
Electromagnetics, Maxwell's Equations, multiphysics, fluid flow, electric field, electrostatic field, magnetic field, magnetostatic field, eddy current, wave guide, non-destructive testing, NDT, Lorentz force, mixing
http://www.adina.com/ADINA_footer.gif 这玩意估计以后也用不起来，在这方面，adina与专业软件比，很不专业。 呵呵，不是很清楚，让大家了解一下，有这么个东西就行。 2# wild_field 这个电磁功能应该主要还是用到多物理场中去，理论上有限元处理电磁问题是完全可行的，但要做要先行者如ansoft那么专业，需要很长的路要走吧。 想做到Maxwell或者HFSS或者FEKO这种级别的估计还得很多年，毕竟adina这方面刚起步，不过要是好好重视起来的话，也许到8.10版本的时候就能有很大的提升了，呵呵 http://www.adina.com/htechbriefs.gif http://www.adina.com/2dmicrowave-er-movie.gif Microwave Heating Microwave heating of materials is extensively used in households and in industries. In this process, the electromagnetic field operates in the high frequency range of 300 MHz to 300 GHz, with electromagnetic scattering and absorption as well as reflection. In this Brief, we illustrate the use of ADINA-EM in simulating the microwave heating of a material sample in an oven, see Figure 1. http://www.adina.com/microwave-schematic.gif
Figure 1Microwave oven
First, we study the two-dimensional electromagnetic resonance in the oven without the sample. The plots in Figures 2 to 4 show magnetic (imaginary component) and electric (real component) field intensities for high excitation frequencies. It is also interesting to note that we can perform a frequency sweep in ADINA-EM, from low to high frequencies, for a same model in a single simulation. The movie above shows electromagnetic field modes in the cavity at different frequencies calculated in a single frequency sweep.
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Figure 2 2D electromagnetic fields: magnetic field intensity (left) and electric field intensity (right)
at the excitation frequency of 2.2 GHz
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Figure 3 2D electromagnetic fields: magnetic field intensity (left) and electric field intensity (right)
at the excitation frequency of 2.45 GHz; note the resonance in the oven
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Figure 4 2D electromagnetic fields: magnetic field intensity (left) and electric field intensity (right)
at the excitation frequency of 2.7 GHz
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Next, we model in three dimensions the microwave heating of the sample. Figures 5 and 6 show electric and magnetic field intensities in the oven on a cutting plane. The band plots of the magnetic and electric fields show the effect of scattering due to the presence of the sample in the oven. The 3D movie shows the temperature in the material sample changing in time during the process of microwave heating. It can be seen that the material sample is heated very uniformly — like we would like our food to be heated, and like it is desirable in material processing or ceramics to prevent cracking.
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Figure 53D microwave heating: magnetic field intensity, real part (left) and imaginary part (right)
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Figure 6 3D microwave heating: electric field intensity, real part (left) and imaginary part (right)
There are many exciting applications of ADINA-EM. For an introduction to ADINA-EM with more applications, please see here. Reference [*]J. Clemens and C. Saltiel, "Numerical modeling of materials processing in microwave furnaces", Int. J. Heat Mass Transfer, Vol. 39, No. 8, pp. 1665-1675, 1996.
Keywords:
Electromagnetics, microwave, radiation, heating, material processing, wave guide, scattering, reflection, absorption, resonance, cavity, furnace, oven, frequency sweep
http://www.adina.com/htechbriefs.gif http://www.adina.com/elecweld-movie.gif Thermo-mechanical Analysis of Electron Beam Welding Electron beam welding is a fusion welding process that utilizes the kinetic energy of a high-velocity electron beam, which upon impact on the workpiece heats it up due to conversion of its kinetic energy to thermal energy. In this Brief, we present the results of a numerical modeling of the electron beam welding process of two steel tubes with different diameters. The numerical results are also compared with the available experimental data (see Ref.). Figure 1 shows a representative specimen and a close-up of the welded region.
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Figure 1The welded specimen
One half of the finite element model used for modeling the welding process is depicted in Figure 2. The movement of the heat source was simulated by applying the heat source to only one prism element along the circumference of the welding zone in each instance. There are 72 prisms along the circumference, each corresponding to 5° rotation of the heat source. The heat flux was applied in pulses, with an idle time between each pulse, to model the actual experimental condition. Since the electron beam welding is usually performed in a vacuum, the convection coefficient was set to zero on the tube walls. Each of the welding pulses was discretized by 100 time steps. Temperature-dependent thermal properties were used for modeling the thermal behavior of the tubes. A temperature-dependent elasto-plastic material model, in which the yield stress and the strain hardening modulus are functions of temperature, was used in the stress analysis. The movie above shows the evolution of the temperature field along the welding path as the heat source moves along the circumference of the tubes.
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Figure 2One half of the finite element model used in the analyses
Figure 3 presents the temperature variation as a function of time, for the welding speed of 10 mm/s, for the points located on the same plane perpendicular to the tube axis but at different depth through the thickness. Figure 4 shows the temperature variation as a function of time for the points located at the same depth through the thickness but at different distances normal to the welding plane for the welding speed of 10 mm/s. Figure 5 shows the temperature variation as a function of time for a single point but for different welding speeds. http://www.adina.com/elecweld-fig3.gif
Figure 3 Time variation of temperature in the weld zone (10 mm/s speed of welding)
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Figure 4 Time variation of temperature in the weld zone (10 mm/s speed of welding)
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Figure 5 Time variation of temperature at a single point, for different welding speeds
Figure 6 depicts the snapshots of the temperature variation as well as the thermal stresses in the tubes resulting from the coupled thermo-mechanical analysis at different times during the pulse period. It can be seen that the lowest values of effective stress occur in the molten pool while the highest values of effective stress occur around the molten pool. Figure 7 presents a comparison between the numerical and experimental results. The isothermal lines obtained using the finite element method are superimposed on a picture of the welded region. A reasonable agreement is reported for the lower parts of the welded region. However, there is a discrepancy between the results for the upper portion. The main reason for the difference is that the specimen has undergone a secondary heat treatment to smooth out the weld face but this secondary heat treatment was not modeled in the numerical analysis.
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Figure 6Temperature field and effective stress band plots for (a) half of the pulse duration (b) end of the pulse (c) end of the idle period between pulses
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Figure 7Comparison between the temperature fields obtained using the FEA and experimental data
This study shows some of the capabilities of ADINA for solving industrial problems involving strong coupling between the thermal field and the mechanical deformations. For more information, please refer to our page on thermo-mechanical coupling capabilities of ADINA. Reference [*]P. Lacki, K. Adamus, "Numerical simulation of the electron beam welding process", Computers and Structures, 2011, in press.
Keywords:
Electron beam welding, thermo-mechanical coupling, residual stress, thermo elasto-plastic material, moving heat source
多物理场耦合分析是发展的趋势，
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