Magnetostrictive sensor having crimped magnetostrictive strip for high temperature operation

摘要

A sensor for use in magnetostrictive testing of a structure. The sensor has a thin ferromagnetic strip with a series of parallel crimps across its width. A first wire coil is wrapped around the width of the strip and along its entire length, such that portions of wire that cross the bottom surface of the strip are located inside the crimps, and portions of wire that are wrapped across the top surface of the strip are between the crimps. The sensor further has a second coil wrapped around the length of the strip, or for pipeline applications, around the pipeline.

主权项

1. A sensor system for use in magnetostrictive testing of a structure, by transmitting a guided wave and receiving a reflected signal, comprising:
a thin strip made from ferromagnetic material, the strip having a bottom surface for placement against the structure and a top surface; wherein the strip has a series of crimps across its width, each crimp being a raised portion of the strip, raised toward or above the top surface of the strip, such that the strip is non planar on both surfaces; a first wire coil wrapped around the width of the strip and along its entire length; wherein wires of the first coil that are wrapped across the bottom surface of the strip are located inside the crimps, and wires of the first coil that are wrapped across the top surface of the strip are between the crimps; a second wire coil wrapped around the length of the strip; wherein the crimps are raised sufficiently from the structure when the strip is coupled to the structure, such that wires of the first coil are contained within the crimps and do not lift the bottom surface of the strip from the structure. an AC pulse generator for applying AC pulses to either the first coil or the second coil; and a DC bias current generator for applying a DC bias current to whichever of the first coil or the second coil does not receive the AC pulse; wherein the DC bias current generator is further operable to apply the DC bias current during each AC pulse and for a period of time corresponding to both transmission of the guided wave and reception of the reflected signal and having a duty cycle of 10% or less.