·Table of Contents ·Methods and Instrumentation | Construction of a compact linear Test Rig for defect Characterization using magnetic flux Leakage technique and Finite Element modelsA. C. Bruno,R. Schifini, G.S.Kühner and C. H. BarbosaDepartamento de Física, Pontifícia Universidade Católica do Rio de Janeiro Rua Marquês de São Vicente 225, Rio de Janeiro, RJ 22453-900, Brasil C. S. Camerini CENPES, Petrobras Quadra 7, Cidade Universitária, Rio de Janeiro, RJ 21949-900, Brazil Contact |
Fig 1: Schematic drawing of the MFL inspection vehicle, top plate containing defects and rail system. The motor arrangement and data acquisition electronics are not shown. |
Fig 2: Drawing of two defect geometries in a 6.35 mm plate. (a) The deeper one has 10 mm in diameter and 5.4 mm maximum depth. (b) The shallow one has 8 mm in diameter and 1.9 mm maximum depth. |
The corresponding measured leakage fields are shown in Figs. 3 (a) and (b) respectively. Note the difference of about one order of magnitude between the peaks of the magnetic field generated by the deeper defect and the magnetic field of the shallow one.
Fig 3: Leakage signals due the two defects. Field shown in (a) corresponds to the deeper defect and field shown in (b) to the shallow one. |
Fig 4: Flowchart of the optimization routine implemented to reconstruct the three dimensional profile of surface-breaking defects. F stands for the error function. |
Fig 5: Results of the recovered three-dimensional defect (a) deeper and (b) shallow. Profile of original and recovered coordinates for the same defect (c) and (d). |
This work is partially supported by CNPq, FINEP-PADCT and PETROBRAS.
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