scholarly journals Investigation of and Components of the Magnetic Flux Leakage in Ferromagnetic Laminated Sample

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Mustafa Göktepe
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Crack Detection ◽  
Industrial Applications ◽  
Magnetic Flux Leakage ◽  
Longitudinal Magnetization ◽  
Flux Lines ◽  
Power Stations ◽  
Leakage Field ◽  
Flux Leakage

The magnetic flux leakage (MFL) technique is most commonly used for crack detection from iron bars, laminated sheets, and steel tubes of ferromagnetic nature. Magnetic flux leakage system induces a magnetic field and detects magnetic flux lines that “leak” or change because of a discontinuity in the magnetized area. An inductive coil sensor or a Hall effect sensor detects the leakage. Magnetic methods of nondestructive testing (NDT) depend on detecting this magnetic flux leakage field. The ferromagnetic specimen is magnetized by suitable methods, and flaws which break the surface or just the subsurface distort the magnetic field, causing local flux leakage fields. It is very important for industrial applications to detect cracks and flaws in metal parts of the steel bridges, power stations, military tools and structures, and so forth. In this study, the inspection of cracks in laminated sheets under longitudinal magnetization will be discussed in detail.

Finite Element Analysis and Research on Corrosion Defect of Tank Floor

2016 ◽  
Vol 853 ◽  
pp. 514-518
Author(s):  
Zhi Jun Yang ◽  
De Shu Chen ◽  
Liang Chen ◽  
Yu Zhuo Liu ◽  
Ran An ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Magnetic Flux ◽  
Magnetic Flux Leakage ◽  
Bottom Plate ◽  
Element Analysis ◽  
Corrosion Defect ◽  
Leakage Magnetic Field ◽  
Leakage Field ◽  
Flux Leakage

Storage tank is an essential vessel in petrochemical industry, and the corrosion of tank is an important reason for the safety hazard. The corrosion of tank bottom plate is more serious than the tank wall, and it is not easy to check and repair, when damaged to a certain extent it will cause the leakage of the media, then lead to waste of energy, environmental pollution, at the same time it will cause a major accident. Magnetic flux leakage testing is widely used in the field of tank floor inspection with the advantages of fast scanning speed, accurate results and so on. In this paper, the finite element simulation and analysis of the corrosion defect leakage magnetic field is used to obtain the data, and the characteristic of the leakage magnetic field is extracted. The effect of defect depth and width and shape on the magnetic flux leakage field is studied, and the distribution curve of the magnetic flux leakage field is obtained.

Analysis of Defect Magnetic Flux Leakage Field Based on Dipole

2013 ◽  
Vol 274 ◽  
pp. 592-595
Author(s):  
Jun Shan Gao ◽  
Jin Wang ◽  
Ke Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Magnetic Field Intensity ◽  
Magnetic Flux Leakage ◽  
Defect Model ◽  
Leakage Field ◽  
Ellipsoidal Model ◽  
The Magnetic Field ◽  
Flux Leakage ◽  
Common Defect

This paper makes an exhaustive analysis to common defect magnetic leakage field based on dipole theory, obtaining the analytical expression of some common injury shapes and exploiting distribution curves of the magnetic field intensity by MATLAB software, and based on this a new scheme is proposed to simulate various injuries using an ellipsoid tables defect model, and finally confirms the superiority of ellipsoidal model in analysis of defect leakage field by comparison.

ANSYS Simulation Technology of Pipeline Magnetic Flux Leakage Inspection

2013 ◽  
Vol 718-720 ◽  
pp. 1000-1005
Author(s):  
Li Jian Yang ◽  
Sen Lin Zhang ◽  
Song Wei Gao
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Electromagnetic Field ◽  
Magnetic Flux ◽  
Oil And Gas ◽  
Gas Pipeline ◽  
Magnetic Flux Leakage ◽  
Field Calculation ◽  
Inspection Method ◽  
Flux Leakage

In order to solve the need of the oil and gas pipeline defect quantification in the real-time online defecting, magnetic flux leakage inspection method was applied to oil and gas pipeline inspection. According to the basic theory of the electromagnetic field, finite element solution of electromagnetic field and ANSYS electromagnetic field calculation theory, using the function of ANSYS 's simulation and calculation for magnetic field, three-dimensional finite element model of the oil and gas pipeline defect was built up. Through simulating, the relationship between defect signal and defect size was found, the optimal distance of the hall sensor lift-off value was verified, the best magnetization of leakage magnetic field was discussed, and various factors to influence the magnetic flux leakage signal is analyzed.

The 3D Magnetic Field Analysis of Excitation Unit of Drill Pipe MFL Testing Based on ANSYS

2013 ◽  
Vol 694-697 ◽  
pp. 1179-1182
Author(s):  
Yi Lai Ma ◽  
Li Lin ◽  
Kai Wen Jiang ◽  
Xu Lin Zhao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Drill Pipe ◽  
Magnetic Flux Leakage ◽  
Field Analysis ◽  
Ansys Software ◽  
Magnetic Field Analysis ◽  
The Cost ◽  
The Magnetic Field ◽  
Flux Leakage

Magnetic flux leakage is one type of electromagnetic nondestructive testing (NDT) which is widely utilized in the testing the integrity of drill pipe in the field. In this paper, the 3D model of excitation unit is completely built and analyzed by ANSYS software. The magnetic field of drill pipe in the combination of full excitation device is showed by ANSYS software instead of the physic experiments which increases the efficiency tremendously and decreases the cost and achieves the anticipated desire. It is considered that this technique can provide the theoretical basis of drill pipe excitation device and the magnetic flux leakage testing of drill pipe.

Finite Element Analysis of Magnetization Reversal Effect Based on Ferromagnetic Specimens

2014 ◽  
Vol 620 ◽  
pp. 127-132
Author(s):  
Xiao Wen Xi ◽  
Shang Kun Ren ◽  
Li Hua Yuan
Keyword(s):  
Magnetic Field ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Magnetic Flux ◽  
Magnetization Reversal ◽  
Tensile Load ◽  
Magnetic Flux Leakage ◽  
Element Analysis ◽  
The Magnetic Field ◽  
Flux Leakage

Using large finite element analysis (FEA) software ANSYS, the stress-magnetization effect on 20# steel specimens with different shape notches is simulated under the geomagnetic field and tensile load. With the stimulation, the magnetic flux leakage fields at certain positions of the surface specimen were measured. Through analysis the relationship between the magnetic flux leakage fields of certain points with tensile stress, the results showed that the magnetic field value at certain positions of specimen surface first decreases and then increases along with the increase of stress, which is called magnetization reversal phenomenon; Different gaps and different positions of the specimen show different magnetization reversal rules; By measuring the maximal variation of the magnetic field value △Hmax at certain positions of the surface specimen and by analyzing its change law, we can roughly estimate specimen stress size and distribution regularity of stress. Moreover, this article also discusses the effect of lifts-off of the probe on the law of stress magnetization.

The Design of a Mechanical Damage Inspection Tool Using Dual Field Magnetic Flux Leakage Technology

2005 ◽  
Vol 127 (3) ◽  
pp. 274-283 ◽  
Author(s):  
J. Bruce Nestleroth ◽  
Richard J. Davis
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
High Magnetic Field ◽  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Metal Loss ◽  
Unexpected Result ◽  
Lower Field ◽  
Study Results ◽  
Flux Leakage

This paper describes the design of a new magnetic flux leakage (MFL) inspection tool that performs an inline inspection to detect and characterize both metal loss and mechanical damage defects. An inspection tool that couples mechanical damage assessment as part of a routine corrosion inspection is expected to have considerably better prospects for application in the pipeline industry than a tool that complicates existing procedures. The design is based on study results that show it is feasible to detect and assess mechanical damage by applying a low magnetic field level in addition to the high magnetic field employed by most inspection tools. Nearly all commercially available MFL tools use high magnetic fields to detect and size metal loss such as corrosion. A lower field than is commonly applied for detecting metal loss is appropriate for detecting mechanical damage, such as the metallurgical changes caused by impacts from excavation equipment. The lower field is needed to counter the saturation effect of the high magnetic field, which masks and diminishes important components of the signal associated with mechanical damage. Finite element modeling was used in the design effort and the results have shown that a single magnetizer with three poles is the most effective design. Furthermore, it was found that for the three-pole system the high magnetization pole must be in the center, which was an unexpected result. The three-pole design has mechanical advantages, including a magnetic null in the backing bar, which enables installation of a pivot point for articulation of the tool through bends and restrictions. This design was prototyped and tested at Battelle’s Pipeline Simulation Facility (West Jefferson, OH). The signals were nearly identical to results acquired with a single magnetizer reconfigured between tests to attain the appropriate high and low field levels.

Testing of a Dual Field Magnetic Flux Leakage (MFL) Inspection Tool for Detecting and Characterizing Mechanical Damage Features

2008 ◽  
Author(s):  
Alex Rubinshteyn ◽  
Steffen Paeper ◽  
Bruce Nestleroth
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Residual Stresses ◽  
High Field ◽  
Mechanical Damage ◽  
Magnetic Flux Leakage ◽  
Low Field ◽  
Field Unit ◽  
Low Magnetic Field ◽  
Flux Leakage

Battelle has developed dual field magnetic flux leakage (MFL) technology for the detection and characterization of mechanical damage to pipelines. The basic principle involves the use of a high magnetic field between 140 and 180 Oersted (11.1 to 14.3 kA/m) and the use of a low magnetic field between 50 and 70 Oersted (4 to 5.6 kA/m). At high magnetic field levels, the flux leakage signal is primarily influenced by changes in the geometry of a pipe wall. At low magnetic field levels, the MFL signal is due to residual stresses and metallurgical changes as well as geometry changes to the pipe caused by mechanical damage and wall thinning. A decoupling signal processing method developed by Battelle is used to isolate the portion of the mechanical damage signals due to metallurgical damage and residual stresses, which allows the characteristics of a dent-gouge feature to be more clearly differentiated. The decoupling method involves first scaling down the high field signal to the level of the low field signal, and then subtracting it from the low field signal. This produces a decoupled signal that is primarily influenced by the residual stresses and metallurgical changes caused by mechanical damage. Rosen has developed a tool to test the dual field technology and is evaluating tool performance by running the tool in a 30 inch diameter pipeline segment. The tool itself is composed of three separate modules coupled together: a high field unit downstream of a low field unit which is downstream of a caliper arm unit that is used to detect and characterize reductions in the internal diameter. The general and magnetic design of the tool, along with the scaling algorithm is discussed. Results from a pull test in a pipe section with dents whose geometry has been independently characterized are also discussed. This work is partially funded by the U.S. Department of Transportation, Pipeline and Hazardous Materials Safety administration (DOT PHMSA) and the Pipeline Research Council International, Inc. (PRCI).

ANSYS Simulation Analysis of the Tri-Axial Pipeline Magnetic Flux Leakage In-Line Inspection

2012 ◽  
Vol 490-495 ◽  
pp. 2086-2090
Author(s):  
Li Jian Yang ◽  
Yan Xiu Su ◽  
Song Wei Gao
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Magnetic Flux ◽  
Simulation Analysis ◽  
Magnetic Flux Leakage ◽  
Ansys Simulation ◽  
Leakage Magnetic Field ◽  
Simulation Results ◽  
Flux Leakage ◽  
Three Components

In order to improve the detect performance of the traditional pipeline magnetic flux leakage(MFL) in-line inspection tools, the method of tri-axial pipeline MFL in-line inspection is advanced. By the three leakage magnetic field components: axial, radial and circumferential, the pipeline defects are recognized. Applying finite element method to build the simulation model of pipeline MFL in-line inspection, then proceeding 3-D simulation analysis. The three components of leakage magnetic field (axial, radial and circumferential) can be obtained by using ANSYS 3-D simulation, and the pipeline defects’ existence as well as the change of the defect’s size can be estimated by the three components’ graph. The simulation results indicate: By the ANSYS 3-D simulation, it proves that the tri-axial pipeline MFL in-line inspection can be achieved and the inspection can be used to improve the level of traditional pipeline MFL in-line inspection.

Nondestructive testing of turbine disk roots using solid-state GMR sensor arrays and an axial directional scanning system

2020 ◽  
Vol 64 (1-4) ◽  
pp. 525-531
Author(s):  
Juhyeon Park ◽  
Hoyong Lee ◽  
Gyejo Jung ◽  
Jinyi Lee
Keyword(s):  
Magnetic Field ◽  
Nondestructive Testing ◽  
Magnetic Flux ◽  
Permanent Magnets ◽  
Turbine Disk ◽  
Magnetic Sensors ◽  
Magnetic Flux Leakage ◽  
Scanning System ◽  
Sensor Probe ◽  
Flux Leakage

A nondestructive testing device, consisting of a scanner and signal processing circuits was developed to detect cracks in turbine disk roots. The scanner consists of a longitudinal feeder and a fir-tree-shaped sensor probe. The feeder inserted the sensor probe along the grooves of the turbine blade attachment. Meanwhile, permanent magnets were placed in opposite direction, to generate a closed magnetic field between the magnetic sensors located on the crests of the sensor probe. The fatigue crack in the turbine disk root occurred in the circumferential direction of the turbine. As a result, magnetic flux leakage was caused by disturbing the flow of closed magnetic field by permanent magnets. The magnetic flux leakage was measured by a magnetic sensor. The effectiveness of the proposed device has been verified using artificial defects introduced into the turbine disk roots by electric discharge machining.

Sign in / Sign up

Export Citation Format

Share Document