Eddy Currents Testing of Long Cylindrical Products with Long Solenoids

The scientific interpretation of the results obtained by eddy currents testing long cylindrical products is much easier when using long rather than short solenoids. The long product is then in an uniform state of magnetic induction. A simple model is developped to size long axial emerging rectangular defects of various widths and depths. For non-ferromagnetic materials, at relatively high frequency, the inductance L varies linearly with the cross-section of the defect and the resistance R varies also linearly with the depth of the defect. The model allows to calculate the linear coefficients of influence. Experimental tests carried on copper and aluminium rods have fully validated the theoretical model. For ferromagnetic materials, the model is modified in order to take the magnetization into account. Experimental tests are in progress and results will be presented elsewhere.</p

Simulation of Cracks Detection in Tubes by Eddy Current Testing

The eddy current testing can be used such as a perfect tool to characterize defects in conducting materials. However, in the latest years, an important progress was made in the development of software for the eddy current testing simulations. Evaluation of the NDT modeling tools is the principal goal of this study. Main concerns of the aeronautic industry and the potential contribution of modeling are discussed and illustrated. Simulation by finite element method is realized with the aim to calculate the electromagnetic energy of interaction between coil and tested part that enables to deduce the impedance response. The objective of this work is the development of a code for efficient resolution of an electromagnetic problem modeling, especially, for the analysis of probe response due to the eddy current process. The validation of developed code was made. The obtained results converge quickly towards the solution given by the (FEMM) code with an average error of 0.018 for real parts of impedance and 0.004 for imaginary parts. The presented results in this work serve to illustrate that the proposed method is practical and they are also of some intrinsic interest especially in the control of aluminum tubes used in aeronautics

Analysis of the Electromagnetic Interferences between Overhead Power Lines and Buried Pipelines

International audienceThe Analysis of electromagnetic interference between high voltage overhead power transmission lines and nearby gas/oil pipeline has been a topic of growing interest for many years. When pipelines are located in shared row with power lines, the pipeline can incur high induced voltages and currents due the AC interference. The induced voltage on pipeline can be dangerous for operator to touch the pipeline as well as pipe corrosion can result from AC discharge. This research evaluates and analyzes the electromagnetic interference effects on oil and gas buried pipelines created by the nearby high voltage transmission lines. The aim is to evaluate the AC corrosion likelihoods of pipelines and suggest proper mitigation solutions

Numerical simulation for cracks detection using the finite elements method

The means of detection must ensure controls either during initial construction, or at the time of exploitation of all parts. The Non destructive testing (NDT) gathers the most widespread methods for detecting defects of a part or review the integrity of a structure. In the areas of advanced industry (aeronautics, aerospace, nuclear …), assessing the damage of materials is a key point to control durability and reliability of parts and materials in service. In this context, it is necessary to quantify the damage and identify the different mechanisms responsible for the progress of this damage. It is therefore essential to characterize materials and identify the most sensitive indicators attached to damage to prevent their destruction and use them optimally. In this work, simulation by finite elements method is realized with aim to calculate the electromagnetic energy of interaction: probe and piece (with/without defect). From calculated energy, we deduce the real and imaginary components of the impedance which enables to determine the characteristic parameters of a crack in various metallic parts

Spatio-temporal aspects of the domain propagation in a spin-crossover lattice with defect

International audienc