Characterization of Magnetic Field in Crack Propagation Stage and Application to Non-Destructive Evaluation

2020 ◽  
Author(s):  
Sheng Bao ◽  
Zhengye Zhao ◽  
Qiang Luo ◽  
Jian Yang
Keyword(s):  
Magnetic Field ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Magnetic Measurement ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Non Destructive ◽  
The Magnetic Field

Abstract Monitoring of fatigue crack propagation is very important in industrial fields. Stress-induced magnetic measurement is a newly developed non-destructive testing technique which can detect early failure of ferromagnetic materials in service. A lot of experiments demonstrate that magnetic measurement is more sensitive compared with other non-destructive testing technologies. In order to explore the correlation between crack propagation and magnetic hysteresis under cyclic stress in X70 pipeline steel, a series of stress-controlled tests were carried out and the changes in magnetic field around cracks during their propagation process were observed throughout the tension-tension fatigue tests. The variations of magnetic field and stress intensity factor K in the crack propagation stage were studied. The results obtained allowed the division of the magnetic behavior of the investigated steels into three stages corresponding to three distinct crack propagation stages. It was found that the magnetic field varies with crack propagation, and the stress intensity factor K increased with the increase of loading cycles. A strong correlation between the variation of the magnetic field and stress intensity factor was recognized, regardless of the loading conditions, maximum load or stress ratio. The results suggest that non-destructive evaluation of fatigue cracks would be possible using this relationship.

The Magnetoelastic Problem for a Soft Ferromatnetic Elastic Half-Plane with a Crack and a Constant Magneic Induction

2009 ◽  
Vol 25 (1) ◽  
pp. 95-102 ◽  
Author(s):  
C.-S. Yeh ◽  
C.-W. Ren
Keyword(s):  
Magnetic Field ◽  
Stress Intensity Factor ◽  
Free Surface ◽  
Stress Intensity ◽  
Stress State ◽  
Intensity Factor ◽  
Half Plane ◽  
Elastic Solid ◽  
Soft Ferromagnetic ◽  
The Magnetic Field

AbstractThe stress state of a magnetized elastic half-plane with a uniformly pressurized crack parallel to the free surface subjected to a uniform magnetic induction Bo is considered. The linear theory for a soft ferromagnetic elastic solid with muti-domain structure, which has been developed by Pao and Yeh [1] is adopted to investigate this problem. A numerical method is developed to determine the magnetoelastic stress intensity factor. The effect of the magnetic field and the boundary conditions on the magnetoelasitc stress intensity factor are shown graphically and numerically.

Magnetoelastic Interaction of a Soft Ferromagnetic Elastic Solid With a Penny-Shaped Crack in a Constant Axial Magnetic Field

1978 ◽  
Vol 45 (2) ◽  
pp. 291-296 ◽  
Author(s):  
Y. Shindo
Keyword(s):  
Magnetic Field ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Axial Magnetic Field ◽  
Penny Shaped Crack ◽  
Soft Ferromagnetic ◽  
Shaped Crack ◽  
Fundamental Equations ◽  
The Magnetic Field

The fundamental equations for soft ferromagnetic elastic materials of multidomain structure are derived in cylindrical coordinates. The basic theory used is one of Pao and Yeh [3] and the soft ferromagnetic elastic solids are considered to be composed of materials with isotropic, cubic or uniaxial symmetry. Using the fundamental equations, the axisymmetric problem for an infinite body with a penny-shaped crack in a constant axial magnetic field is investigated. A solution for the infinite solid is obtained by the method of two simultaneous dual integral equations. The magnetoelastic stresses and the Maxwell stresses are expressed in closed forms. By referring to a set of polar coordinates r1 and θ1 measured from the crack periphery, the dependence of the local stresses on r1 and θ1 is also determined in closed elementary form. As in the classical case, the stresses possess the familiar inverse square-root singularity at the crack boundary. The stress-intensity factor, however, is found to depend on the magnetic field. When the magnetic field reaches a critical value, the surface of a crack is unstable. The effect of magnetic fields on the stresses and the stress-intensity factor, and a comparison of the plane strain and axisymmetric solutions are shown graphically.

scholarly journals Giant magneto resistance (GMR) sensors for non destructive testing

2021 ◽  
Author(s):  
◽  
Joseph Bailey
Keyword(s):  
Magnetic Field ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Current Frequency ◽  
Steel Pipes ◽  
Electronic Measurement ◽  
Gmr Sensors ◽  
Non Destructive ◽  
Magneto Resistance ◽  
The Magnetic Field

<p>The thesis investigates the use of giant magneto resistance sensors for eddy current testing in order to identify defects in steel pipes. An automated test rig which included the device under test, sensor array, excitation unit, electronic measurement equipment, mechanical setup and LabVIEW automation was designed and built. This was used to investigate the effect of excitation parameters such as current, frequency and distance to the pipe. Some preliminary algorithms to improve the signal were developed and tested. The effect of the shape and size of the defect and aluminum shield on the magnetic field was investigated. A qualitative model to describe the magnetic field, including measured defect signals, was developed. Minimum defect parameters and maximum distance values were evaluated in the context of signal to noise.</p>

scholarly journals Giant magneto resistance (GMR) sensors for non destructive testing

2021 ◽  
Author(s):  
◽  
Joseph Bailey
Keyword(s):  
Magnetic Field ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Current Frequency ◽  
Steel Pipes ◽  
Electronic Measurement ◽  
Gmr Sensors ◽  
Non Destructive ◽  
Magneto Resistance ◽  
The Magnetic Field

<p>The thesis investigates the use of giant magneto resistance sensors for eddy current testing in order to identify defects in steel pipes. An automated test rig which included the device under test, sensor array, excitation unit, electronic measurement equipment, mechanical setup and LabVIEW automation was designed and built. This was used to investigate the effect of excitation parameters such as current, frequency and distance to the pipe. Some preliminary algorithms to improve the signal were developed and tested. The effect of the shape and size of the defect and aluminum shield on the magnetic field was investigated. A qualitative model to describe the magnetic field, including measured defect signals, was developed. Minimum defect parameters and maximum distance values were evaluated in the context of signal to noise.</p>

Stress Intensity Factor Calculation Using a Weight Function Method

2007 ◽  
Author(s):  
Rui Sun ◽  
Zongwen An ◽  
Hong-Zhong Huang ◽  
Qiming Ma
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Weight Function ◽  
Function Method ◽  
Method Comparison ◽  
Finite Size ◽  
Unstable Crack ◽  
Weight Function Method

Propagation of a critical unstable crack under the action of static or varying stresses is determined by the intensity of strain field at tips of the crack. Stress intensity factor (SIF) is an important parameter in fracture mechanics, which is used as a criterion to judge the unstable propagation of a crack and plays an important role in calculating crack propagation life. SIF is related to both geometrical form and loading condition of a structure. In the paper, a weight function method is introduced to study crack propagation of center through cracks and edge cracks in a finite-size plate. In addition, finite element method, linear regression, and polynomial interpolating technique are used to simulate and verify the proposed method. Comparison studies among the proposed and current methods are performed as well. The results show that the weight function method can be used to calculate SIF easily.

Electromagnetic Effect of Eddy Currents in Composites with Conductive Components: Magnetic Field Strengthening and its Simple Analytical Estimation

2018 ◽  
Vol 284 ◽  
pp. 37-42 ◽  
Author(s):  
R.R. Sattarov ◽  
T.A. Volkova ◽  
I.Z. Gubaydullin
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Compatibility ◽  
Eddy Currents ◽  
Electromagnetic Effect ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Compatibility Analysis ◽  
Dynamic Materials ◽  
Analytical Estimation ◽  
Non Destructive

Composites and dynamic materials that include conductive components are becoming a suitable choice in different applications. The eddy currents are generated when the conductive components are placed in alternating magnetic field. The eddy currents decrease the primary field and this effect has been well studied and it is used for electromagnetic shielding. Besides, the magnetic field increases in small space near edges of the conductive components. While this effect of magnetic field strengthening is known, it is rarely examined. We will introduce a simple model that can be appropriate for the conductive components in form of long thin sheets. We analytically analyze the model and obtain expressions that give upper bounds for increasing of the net magnetic field. The electromagnetic effect of strengthening should be taken into account when considering an application of the composites. The results are useful for electromagnetic compatibility analysis, non-destructive testing and monitoring of composite and dynamic materials with conductive components.

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