Impact of Bounding Media on the Attenuation Characteristics of Magnetostrictive Signal Obtained from Pipe Embedded in Soil and Sand

Abstract

An indigenously developed magnetostrictive sensing (MsS) device coined "MagStrics" has been used to obtain MsS signals in pipes embedded in sand or soil. The device comprises a rapidly quenched amorphous ribbon prepared in the laboratory, which acts as a transducer as well as the sensing element. In contrast to conventionally used CoFe-based crystalline alloys as sensing elements requiring kiloOersteds of the operating field, the absence of magnetocrystalline anisotropy in the present amorphous ribbons required few Oersteds of the magnetic field. Even at such low magnetic field actuation, MagStrics delivers noticeable MsS signals to distinguish the different attenuation characteristics due to soil or sand as bounding media. In addition to the novel and portable device used with amorphous ribbons as a transducer-sensor element, the investigation involves the analysis of signal intensity ratios, and transmission/reflection co-efficient through the 'Dipstick' technique. Using this technique, the overall attenuation characteristics of MsS signals in sand and soil have been manifested. The experimental attenuation in signal from different bounding media like sand and soil has been confirmed using COMSOL multiphysics simulation to display the impact of bounding media on stress and displacement. The scope of novel characteristics of the device along with its thin transducer-sensor element inducing efficient magneto-mechanical coupling for the detection of defects has been discussed.