Electromagnetism as a means for understanding materials mechanics phenomena in magnetic materials

Abstract

Electromagnetic properties are an interesting means for monitoring a variety of materials' mechanical properties in ferro- and paramagnetic materials non-destructively. Those properties include uni- und multi-axial stress states as well as plasticity and fatigue damage and can be measured at macro- as well as at microscopic scales, depending on what measurement equipment will be used. The article describes the general electromagnetic phenomena to be considered as well as the equipment to be used before presenting a variety of different experimental results from which the materials mechanical properties mentioned above can be directly derived being an ideal means for monitoring the health of any magnetic metallic structure

Quantitative Nondestructive Evaluation of Plastic Deformation in Carbon Steel Based on Electromagnetic Methods

“…8, magnetic incremental permeability is defined as the gradient of the minor loops which is superimposed onto a major hysteresis curve, i.e., the minor loops are generated in process when the material is magnetized and demagnetized by a large magnetic field. 17) In practice, the EM magnet with a driven current of low frequency is used to magnetize the material to different point at the major loop and an ECT probe of high frequency is used to generate the minor loop and to measure its gradient that is corresponding to the MIP value. The phase information of the ECT signals included in the real and imaginary values of the MIP signals is also important for the material characterization.…”

“…On the other hand, the MIP is defined as the average slope of the minor hysteresis loop generated by an alternating magnetic field of amplitude smaller than the magnetic coercive force at different point of the major hysteresis loop. 17,18) The MIP can reflect the reversible magnetization information through its profiles feature parameters during the whole magnetization and demagnetization procedure, and consequently is considered as a good index of the plastic deformation. In addition, the perturbation information of the leakage magnetic field surrounding the specimen surface measured by the Magnetic Flux Leakage (MFL) method is also closely correlated with the states of orientation and irreversible movement of magnetic domains caused by the plastic strains in a ferromagnetic material.…”

Zustandserfassung von Stahlbauwerken mithilfe akustischer und elektromagnetischer Verfahren der ZfP

“…Gegenüber der plastischen Dehnung sich als noch sensitiv erweisende Parameter sind die elektromagnetische Impedanz wie auch das Barkhausenrauschen, die bei ferromagnetischen Stählen gut messbar sind . Durch die Magnetisierung der Stähle werden in der Domänenstruktur Blochwandbewegungen erzeugt, wobei die Blochwände an Imperfektionen (z.…”

Eine neuartige innovative Auswertemethode für mikromagnetische Kennwerte zur Überwachung von Fügestellen und Strukturbauteilen im Rahmen des Structure Health Monitoring

“…Bei der in Bild gezeigten Form des Prüfkopfes handelt es sich um eine Standartvariante, die universell für eine Vielzahl von Messaufgaben verwendet werden kann. In werden auf Grundlage dieses Messsystems weitere anwendungsbezogene Sensorengeometrien und Miniaturisierungsmöglichkeiten des Systems aufgezeigt.…”