Detection of Fatigue Damage Prior Crack Initiation with Scanning SQUID Microscopy

Żokowski

2015

SSP

The paper presents the theoretical and experimental results from evaluating the early phase of material fatigue and discusses the issues concerning the example of two object classes: supporting structures and shaft working under real environmental conditions. In theoretical considerations, the Hall-Petch and Bailey-Hirsch relationships between microstructure and mechanical parameters are given. Magneto-mechanical effects and the magnetic passive observer have been used for evaluating the early phase of material fatigue. The Metal Magnetic Memory method of structural health assessment was verified and the potential for a reliable diagnosis of damage to the ferromagnetic material at the 1st and 2nd stage was confirmed.

Section: Theoretical Backgroundmentioning

confidence: 99%

Magneto-Mechanical Effects in NDE & SHM Applications

Żokowski

2015

SSP

“…In geocentric spherical coordinates (longitude λ, latitude ϕ', radius r) it can be written as the negative spatial gradient of a scalar potential. (4) where N is the degree of the numerical model, a = 6371200 m is the geomagnetic reference radius, ( ) Such a model can then be evaluated at any desired localisation to provide the magnetic field vector, its direction or the anomaly of the total intensity of the field. Verified models of Earth's magnetism enable to obtain an accurate reference signal (B m_ref = B m ±5 nT) for MMM expert analysis, Fig.…”

Section: A Model Of the Earth's Magnetic Fieldmentioning

confidence: 99%

“…Magneto-mechanical effects are more and more often used to diagnose critical structural elements, that are made of ferromagnetic and paramagnetic materials. In non-destructive testing (NDT) and systems to monitor early fatigue symptoms (structural health monitoring, SHM, prognosis health management, PHM) following processes are used [1][2][3][4][5]:…”

Section: Introductionmentioning

confidence: 99%

The Reference Signal of Geomagnetic Field for MMM Expert Systems

2012

KEM

The first step of a methodological approach to the validation of the metal magnetic memory (MMM) method in non-destructive testing (NDT) applications and in systems used for the diagnosis of early stages of material fatigue in mechanical constructions (structural health monitoring, SHM, and prognosis health management, PHM) has been presented in the paper. The study is focused on the properties of the external natural source of magnetisation of the object under MMM examination and the impact of its components. The precise data of the Earth's geomagnetism measurements (from ground stations and satellites) and the revised model of the Earth's magnetism can be applied in order to calibrate high sensitive magnetic field sensors, validate measurement results and extend the functional capacity of the MMM method.

“…Magneto-mechanical effects (MME) are increasingly used to diagnose critical structural elements that are made of ferromagnetic and paramagnetic materials. In non-destructive testing (NDT) and systems to monitor early fatigue symptoms (structural health monitoring, SHM, prognosis health management, PHM), the following processes are used [1][2][3][4][5]: • reversible paraprocesses (Joule'a effect, Villari effect and derivative phenomena), • irreversible paraprocesses (E effect, Metal Magnetic Memory (MMM), which is an equivalent of Natural Remanent Magnetization (NRM) in geophysics).…”

Section: Introductionmentioning

confidence: 99%

The MMM Expert System: From a Reference Signal to The Method Validation

Fatigue of Aircraft Structures

2012

This paper presents the first step in the methodological approach to the validation of the metal magnetic memory (MMM) method in the non-destructive testing (NDT) applications and in the systems used for diagnosis of early stages of material fatigue in mechanical constructions (structural health monitoring, SHM, and prognosis health management, PHM). The study is focused on the properties of the external natural source of magnetisation of the object under MMM examination and the impact of the magnetisation components. The precise data obtained from measurements of the Earth's geomagnetism (from ground stations and satellites) and the revised model of the Earth's magnetism can be applied in order to calibrate high sensitivity magnetic field sensors, validate the measurement results and extend the functional capacity of the MMM method.