Brahim Ramdane

Microscopic and macroscopic electromagnetic and thermal modeling of Carbon Fiber Reinforced Polymer Composites

An electromagnetic and thermal model of carbon fiber reinforced polymer composite material is introduced. This model takes into account the influence of different fiber orientations on the electromagnetic parameters. These parameters are defined in microscopic scale and introduced in finite-element-method model in macroscopic scale.

Interaction Between Electromagnetic Field and CFRP Materials: A New Multiscale Homogenization Approach

In this paper, a new multiscale homogenization method is introduced to calculate the field and current distribution inside carbon fiber reinforced polymer composites submitted to an external electromagnetic field. In the microscopic scale, the real structure of the material is taken into account and electromagnetic and electrical equivalent properties are calculated using finite-element method (FEM). In the macroscopic scale, these properties are introduced in an impedance network or in an anisotropic-finite elements method according to the working frequency. The simulating results are in accordance with experimental ones and will allow a better modeling of composites.

3-D Numerical Modeling of the Thermo-Inductive Technique Using Shell Elements

Thermo-inductive testing is a new technique used for health investigations on different components of automotive and aeronautic industries. In this technique, eddy current deviation around the default creates local heating which can be detected by an infrared camera. The purpose of this work is to develop a 3-D finite-element model as a support tool to study the reliability of the technique. To reduce the number of unknowns, shell elements are introduced to model defects or thin conductive regions. Inspected materials are classified into metallic and composites. Investigations on various parameters of the technique and crack dimensions are performed in order to optimize the method. Experimental and simulation results show that the method is well suited.

3-D Modeling of Thermo Inductive Non Destructive Testing Method Applied to Multilayer Composite

In this paper, a 3-D modeling of a thermo inductive nondestructing testing (NDT) technique applied to carbon fiber reinforced polymer (CFRP) composite is presented. A multiscale approach is used to calculate the electromagnetic and thermal field distribution. The relevance of the technique is then discussed for different positions of flaws and the optimal frequency is estimated.

Electromagnetic and thermal modeling of composite materials using multilayer shell elements

In this paper, a methodology based on shell elements is presented to model the electromagnetic behavior of multilayered conductive composite materials. The standard 3-D finite-element formulation is accomplished by a multilevel shell element representation. This leads to a reduced number of unknowns which improve the system convergence and consequently the computational time. The model developed will be validated with classical 3-D finite-element method and experimental results.

Non Linear Homogenization for Calculation of Electromagnetic Properties of Soft Magnetic Composite Materials

A non linear homogenization approach, based on 3D edge finite elements method, is used to determine the equivalent electromagnetic properties of the Soft Magnetic Composites (SMC). A new geometry generation algorithm is introduced to take into account the material density, the randomized size and location of the SMC particles and the insulation layer around the particles. A modified Preisach hysteresis model associated with a new analytical Lorentz function is developed to calculate the homogenized hysteresis loops from intrinsic properties of its constituents.

Computations of Source for Non-Meshed Coils With A–

In this paper, different ways to compute electromagnetic source fields for non-meshed coils will be described for magnetic vector potential A and electric scalar potential V formulation (A - V formulation). The originality of this paper is demonstrated by the source computations for A- V formulation with non-meshed coils. Usually, coils for A- V formulation are meshed, and non-meshed coils are studied with reduced magnetic vector potential Ar and electric scalar potential V formulation (Ar - V formulation). Different source computations for A - V formulation will be applied on an induction machine with non-meshed coils.

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AC losses in superconducting cables are generated by a time varying environment. These losses heat the cable and impact the cooling system. Nexans is today on the edge of manufacturing superconducting tubes with HTS tapes to create compact high power cables. No study has been done yet on the numerical modelling of ac losses for this new geometry. This article presents the recent development of the creation of a finite-element model (FEM) model to estimate the ac hysteresis losses in a tube. The E-J nonlinearity and convergence issues were solved with the use of a H-formulation. Several E-J formulations have also been compared. To validate the model, an experiment has been performed with a superconducting commercial tape with different waveform of current at different amplitudes and frequencies. Numerical results have been compared to analytical calculations with self-field and external magnetic field losses. In a power cable, HTS tubes are exposed to both a transport current and external magnetic field. The behavior of the tube under both a time varying current and external magnetic field has been studied. Finally some geometries of small cables made of 3 or 6 tubes have been modeled.

Formulation Using Edge Elements

Due to their high-current-carrying capacity, round geometry, and low cost, MgB2 wires are promising candidates for realizing high-power cables. However, their operating temperature between 4.2 K and 25 K makes ac losses a critical issue for those cables. To optimize the cable architecture for minimizing ac losses, one must be able to predict them quite accurately. As a first step in this direction, we addressed the numerical computation of a single multifilamentary MgB2 wire that forms the basic element of a high-current cable. The wire under consideration has 36 twisted MgB2 filaments disposed on three concentric layers and embedded in a pure-nickel matrix. An initial comparison between 2-D and 3-D finite elements was performed to justify the need for a full 3-D model, without which coupling losses in the matrix cannot be modeled properly. This is of prime importance since coupling loss is the dominant loss mechanism at high applied fields. Then, simulations of simpler geometries (6- and 18-filament wires) submitted to various transport currents and/or applied fields were performed to identify trends in ac losses and find the best numerical tools for scaling up simulations to the full 36-filament case. The complexity of the model was progressively increased, starting with MgB2 filaments in the air matrix and then adding electrical conductivity and magnetic properties in the nickel matrix.

Numerical Modelling of AC Hysteresis Losses in HTS Tubes

The purpose of this paper is to introduce periodic and antiperiodic boundary conditions in the natural element method (NEM). It is shown that as the NEM shape functions verify the Kronecker delta property, the imposition of such boundary conditions can be done in an easy way as in the finite-element method (FEM). These boundary conditions are important because they allow exploitation of the inherent symmetry of the electromagnetic devices. Therefore, with these techniques the NEM can now easily take advantage of the symmetry of electrical machines. The proposed approach is evaluated, and its results are compared with those obtained by the traditional FEM.