Flnite Element Model Research Articles

FINITE ELEMENT ANALYSIS AND EXPERIMENTAL STUDY OF THE NEAR-MAGNETIC FIELD FOR DETECTION OF ROTOR FAULTS IN INDUCTION MOTORS

This paper deals with the flnite element analysis and experimental study concerning the in∞uence of the broken bar and rotor dynamic eccentricity faults on the magnetic fleld outside a squirrel-cage induction motor. The spatial distribution of the magnetic fleld, the time variation of the magnetic ∞ux density at a point outside the machine and the time variation of the electromotive force delivered by a coil sensor are evaluated based on the flnite element models of the healthy and faulty states of the motor. The increase of amplitude from the healthy to the faulty states of some low frequency harmonics measured in the near-magnetic fleld is emphasized. For broken bar fault, the increase of the amplitudes of speciflc harmonics of the coil sensor electromotive force, with frequency lower than 25Hz, is experimentally conflrmed.

Parameter optimization of dissimilar resistance spot welding on ultra-high strength hot-stamped steel and mild steel by numerical simulation

In this study, a coupled axisymmetric flnite element model (FEM) was built to simulate the resistance spot welding (RSW) process between ultra-high strength hotstamped (UHSS) and mild steel by SORPAS software. Via simulating this process, the temperature distribution and dynamic temperature curves of the welding area were studied, and welding spatter phenomena were predicted and validated by comparing them with experimental results. By adjusting the welding parameters in numerical simulation, appropriate welding parameters were achieved. Moreover, the mechanical properties of the welding joints under the optimized conditions were also compared with those of not optimized. The study results have already been applied in a manufacturing production. It can also provide guidance for the RSW on UHSS and mild steel.

Comparison of Cellular Automaton and Phase Field Models to Simulate Dendrite Growth in Hexagonal Crystals

A cellular automaton (CA){flnite element (FE) model and a phase fleld (PF){FE model were used to simulate equiaxed dendritic growth during the solidiflcation of hexagonal metals. In the CA{FE model, the conservation equations of mass and energy were solved in order to calculate the temperature fleld, solute concentration, and the dendritic growth morphology. CA{FE simulation results showed reasonable agreement with the previously reported experimental data on secondary dendrite arm spacing (SDAS) vs cooling rate. In the PF model, a PF variable was used to distinguish solid and liquid phases similar to the conventional PF models for solidiflcation of pure materials. Another PF variable was considered to determine the evolution of solute concentration. Validation of both models was performed by comparing the simulation results with the analytical model developed by Lipton{Glicksman{Kurz (LGK), showing quantitatively good agreement in the tip growth velocity at a given melt undercooling. Application to magnesium alloy AZ91 (approximated with the binary Mg{8.9 wt% Al) illustrates the di‐culty of modeling dendrite growth in hexagonal systems using CA{FE regarding mesh-induced anisotropy and a better performance of PF{FE in modeling multiple arbitrarily-oriented dendrites growth.

GENERAL 2-D TRANSIENT EDDY CURRENT FORCE EQUATIONS FOR A MAGNETIC SOURCE MOVING ABOVE A CONDUCTIVE PLATE

When a magnetic source is moved and/or oscillating above a conductive linear plate a traveling time varying magnetic fleld is created in the airgap. This fleld induces eddy currents in the plate that can simultaneously create normal and tangential forces. The transient flelds and the forces created by the magnetic source are modeled using a novel 2-D analytic based A-` method in which the presence of the source fleld is incorporated into the boundary conditions of the plate. The analytic based solution is obtained by using the spatial Fourier transform and temporal Laplace transform. The performance of the method is compared with a 2-D transient flnite element model with a Halbach rotor source fleld. The derived transient force equations are written in a general form so that they can be applied to any magnetic source.

SMART ELECTROMAGNETIC SIMULATIONS: GUIDELINES FOR DESIGN OF EXPERIMENTS TECHNIQUE

Electromagnetic design problems usually involve a large number of varying parameters. A designer can use difierent kinds of models in order to achieve optimum design. Some models, e.g., flnite-element model, can be very precise: however, it requires large computational costs (i.e., CPU time). Therefore, the designer should use a screening process to reduce the number of parameters in order to reduce the required computational time. In this paper, using the Design of Experiments (DOE) approach to reduce the number of parameters is explored. The beneflts of this technique are tremendous. For example, once researchers realize how much insight and information can be obtained in a relatively short amount of time from a well-designed experiment, DOE would become a regular part of the way they approach their simulation projects. The main objective of this paper is to apply the DOE technique to electromagnetic simulations of difierent systems and to explore its efiectiveness on a new fleld, namely the magnetic refrigeration systems. The methodology of the DOE is presented to assess the efiects of the difierent variables and their interaction involved in electromagnetic simulations design and optimization processes.

Dynamic Aeroelasticity of Structurally Nonlinear Configurations Using Linear Modally Reduced Aerodynamic Generalized Forces

Steady state and time domain methods for integrating commonly used frequency-domain unsteady aerodynamic modeling based on a modal approach with full order flnite element models for structures with geometric nonlinearities are introduced. The methods are aimed at airplane conflgurations where geometric stifiness efiects are important but where deformations are moderate, ∞ow is attached, and linear unsteady aerodynamic modeling is adequate, such as joined-wing and strut-braced wings at small to moderate angles of attack or low aspect ratio wing. Results obtained using full order nonlinear structural modeling and full order aerodynamic modeling (including aerodynamic in∞uence coe‐cients for all aerodynamic panels) are compared to results obtained using full order structural modeling with generalized aerodynamic matrices obtained using a modal approach.