Optimization of Flexible Eddy Current Patterns with Low Sensitivity to Lift-Off

International audienceEddy Current is a powerful mean of detection of defects located close to the surface in conductive parts. The use of winding coils has shown good efficiency and gave good results in lots of applications. Nevertheless, it reveals some limits in some cases, when the part has a complex shape for instance. Therefore, other technologies are investigated such as coils etched on kapton film. Thanks to this technology, it is possible to design efficient probes with a low sensitivity to lift-off, on the one hand thanks to the flexibility of the sensor, and on the other hand thanks to the intrinsic design of the pattern. The paper presents the method to optimize these two patterns and a comparison between simulation data and experimental data

Li and Li isotopic composition of hydrothermally altered sediments at Middle Valley, Juan De Fuca

Li and Li isotopes have been measured in the clay fraction of sediments recovered from the Middle Valley hydrothermal site on the Juan De Fuca Ridge. The Li content of pure detrital clays is 51 ppm while hydrothermal clays and carbonates have lower Li (22±11 ppm). However, there is no clear relationship between the mineralogy of the hydrothermal alteration products and their Li content. The δ7Li value of the detrital clays is +5.8‰. Hydrothermal clays and carbonates have δ7Li in the range of -3.9‰ to +7.8‰; these values do not seem to be dependent on the temperature at which they formed. Modelling of the Li and Li isotope systematics indicates that the fluid from which the alteration products form is significantly enriched in Li (higher than 10,000 µmol kg-1) relative to pore fluids recovered from within the sediments (up to 589 µmol kg-1; [Wheat, C.G., M.J. Mottl, 1994. Data report: trace metal composition of pore water from Sites 855 through 858, Middle valley, Juan De Fuca Ridge. In Mottl, M.J., Davis, E.E., Fisher, A.T., Slack, J.F. (Eds.), Proc. ODP, Sci. Res. 139: 749–755]), and that this Li is derived from sediment. Thus, the alteration products are not in equilibrium with their conjugate pore fluids; rather, the alteration minerals formed at lower water/sediment ratios. This suggests that fluid flow pathways at Middle Valley were more diffuse in the past than they are today

Development of flexible array eddy current probes for complex geometries and inspection of magnetic parts using magnetic sensors

39th Annual Review of Progress in Quantative Nondestructive Evaluation (QNDE), Denver, CO, JUL 15-20, 2012International audienceEddy Current Technique is a powerful method of inspection of metal parts. When size of flaws decreases, inspection areas become hardly accessible or material is magnetic, traditional winding coil probes are less efficient. Thanks to new CIVA simulation tools, we have designed and optimized advanced EC probes: flexible EC probe based on micro-coil arrays and EC probe with magnetic sensors, including specific electronics

Development of eddy current probes based on magnetoresistive sensors arrays

Conference of 40th Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2013, Incorporating the 10th International Conference on Barkhausen and Micro-Magnetics, ICBM 2013 ; Conference Date: 21 July 2013 Through 26 July 2013; Conference Code:105840International audienceEddy Current Technique is a powerful method for detection of surface notches and of buried flaws during inspection of metallic parts. Recent EC array probes have demonstrated a fast and efficient control of large surfaces. Nevertheless, when the size of flaws decreases or the defect is rather deep, traditional winding coil probes turn out to be useless. Magnetoresistive sensors present the advantages of flat frequency response and micron size. These sensors are hence very attractive for the detection of buried defects that require low frequencies because of skin depth effect. An optimization of the probe with magnetoresistive sensors as receivers has been made by simulations using CIVA software and finite elements methods with OPERA. EC probes for buried flaw detection have been designed. Experimental results have been compared with simulations

3D modeling of a magneto-optic image by a dyadic Green's functions approach

Communication to : Conference on review of progress in quantitative nondestructive evaluation (QNDE), Bellingham (USA), July 14-19, 2002SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2003 n.20 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Corrosion and cracks detection in metallic structures by magneto optic image processing

Communication to : QCAV 2001, Le Creusot (France), May 21-23, 200Available from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2001 n.108 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc