Nondestructive evaluation of ferromagnetic cables and ropes using magnetostrictively induced acoustic/ultrasonic waves and magnetostrictively detected acoustic emissions

An apparatus for the nondestructive evaluation of ferromagnetic material comprising:

• a transmitting coil of at least one turn positioned adjacent to or encompassing a first location, proximate to a surface of said ferromagnetic material;
• a first linearizing DC magnet adjacent said transmitting coil, said first DC magnet creating a first linear magnetic field within a volume of said ferromagnetic material;
• a signal generator and power amplifier capable of supplying said transmitting coil
• with a current sufficient to create fluctuations in said first magnetic field;
• a receiving coil of at least one turn positioned adjacent to or encompassing a second location, proximate to a surface of said ferromagnetic material;
• a second linearizing DC magnet adjacent said receiving coil, said second DC magnet creating a second linear magnetic field within a volume of said ferromagnetic material;
• a signal conditioner for amplifying and filtering a current within said receiving coil, said amplified and filtered current being a signal indicative of fluctuations in said second magnetic field;
• and
• a display means for displaying said signal and for allowing a test operator to interpret said signal and thereby interpret said fluctuations in said second magnetic field;
• wherein said fluctuations in said first magnetic field induce a magnetostrictive effect within a volume of said ferromagnetic material and generate primary acoustic waves within said material, and said fluctuations in said second magnetic field resulting from an inverse magnetostrictive effect caused by secondary acoustic waves within said ferromagnetic material, said secondary acoustic waves occurring as a result of said primary acoustic waves being reflected from said fractures, cracks, and other anomalies within said ferromagnetic material;
• and
• wherein said interpretation of said signal includes identifying a location and a degree of deterioration of said fractures, cracks, and other anomalies.

An apparatus for the nondestructive monitoring of ferromagnetic material comprising:

• a receiving coil of at least one turn positioned adjacent to or encompassing a location, proximate to a surface of said ferromagnetic material;
• a linearizing DC magnet adjacent said receiving coil, said DC magnet creating a linear magnetic field within a volume of said ferromagnetic material;
• a signal conditioner for amplifying and filtering a current within said receiving coil, said amplified and filtered current being a signal indicative of fluctuations in said magnetic field;
• and
• a recording means for storing said signal and for subsequently allowing a test operator to interpret said signal and thereby interpret said fluctuations in said magnetic field;
• wherein said fluctuations in said magnetic field result from an inverse magnetostrictive effect caused by acoustic waves within said ferromagnetic material, said acoustic waves being generated from said fractures, cracks, and other anomalies within said ferromagnetic material;
• and
• wherein said interpretation of said signal includes identifying a location and a degree of deterioration of said fractures, cracks, and other anomalies.