Metal Magnetic Memory Testing of Welded Joints under Fatigue Load

2017 ◽  
Vol 898 ◽  
pp. 1069-1078
Author(s):  
Ning Qiao ◽  
Mu Xiao Shan ◽  
Ye Zheng Li
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Crack Propagation ◽  
Normal Component ◽  
Fatigue Loading ◽  
Fracture Morphology ◽  
Magnetic Flux Leakage ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Flux Leakage

To investigate the influence of stress concentration, crack propagation and types of fatigue loading on metal magnetic memory signals, two groups of fatigue experiments with different types of fatigue loading were carried out on Q235B steel welded joint. The normal components of magnetic flux leakage were measured by metal magnetic memory tester in the course of fatigue test, and the fracture surfaces of specimens were observed by scanning electron microscopy after fatigue tests. The experimental results showed that the normal components of magnetic flux leakage filed, as well as the metal magnetic memory signal, changed polarity and their gradients have peak values at stress concentration zones. The zero position of the normal component of magnetic flux leakage changed gradually with increasing cycle numbers. In addition, the metal magnetic memory signal feature of fatigue crack propagation was affected by the loading type clearly. Moreover, a combination of brittle rupture and ductile rupture was obtained in the fracture morphology figure.

Numerical Simulation Study of Stress-Magnetization Effect on Different Notch Steel Specimens

2014 ◽  
Vol 989-994 ◽  
pp. 891-897 ◽  
Author(s):  
Xiao Wen Xi ◽  
Shang Kun Ren ◽  
Yin Huang
Keyword(s):  
Magnetic Flux ◽  
Quantitative Research ◽  
Tensile Load ◽  
Magnetic Flux Leakage ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Element Analysis ◽  
Damage Degree ◽  
Testing Technology ◽  
Flux Leakage

To study the mechanism of metal magnetic memory (MMM) testing technology, the stress-magnetization effect on 20 steel specimens with different notch angles under exercise of the geomagnetic field and tensile load is simulated by using the finite element analysis (FEA) software ANSYS. With the stimulation, the stress and magnetic flux leakage distribution of the specimens is given. The results showed that internal stress distribution of different notch specimens under external tensile effects is different; The curves of relationship between damage degree of stress concentration and the distribution of magnetic flux leakage is also related to the defect shape and structure; Magnetization decreases with increases of stress at first and then increases with continuing increase of stress, which is called stress magnetization reversal. It provides an important reference for the quantitative research of metal magnetic memory technology.

scholarly journals Magnetic Memory Inspection of an Overhead Crane Girder – Experimental Verification

2019 ◽  
Vol 26 (2) ◽  
pp. 69-76
Author(s):  
Agnieszka Kosoń-Schab ◽  
Jarosław Smoczek ◽  
Janusz Szpytko
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Material Handling ◽  
Impact Load ◽  
Ferromagnetic Material ◽  
The Self ◽  
Magnetic Flux Leakage ◽  
Magnetic Memory ◽  
Earth Magnetic Field ◽  
Flux Leakage

Abstract The safety and efficiency of material handling systems involve periodical inspections and evaluation of transportation device technical conditions. That is particularly important in case of industrial cranes, since they are subjected to a large impact load and mechanical stresses acting on the crane's structure and equipment. The paper considers the possibility of a crane structure inspection using the metal magnetic memory (MMM) method. As an advanced non-destructive technique, this method can be employed for inspection of crane structure during operation, which leads to reduce the down time costs and increase the safety confidence in the monitoring process. The MMM technique is effective for early identification of the possible defect location and detecting the micro-damage in ferromagnetic structures through detecting the stress concentration areas. The basic principle of MMM method is the self-magnetic flux leakage signal that correlates with the degree of stress concentration. This method allows detecting early damage of ferromagnetic material through performing measurement in the earth magnetic field, without the use of a special magnetizing device. The paper presents the experimental results carried out on the double-girder overhead travelling crane with hoisting capacity 1000 kg. The influence of the load variation and duration time on the intensity of the self-magnetic flux leakage signal is analysed and discussed.

DETECTION OF CRACKED POSITION DUE TO CYCLIC LOADING FOR FERROMAGNETIC MATERIALS BASED ON MAGNETIC MEMORY METHOD

2015 ◽  
Vol 75 (7) ◽  
Author(s):  
Azli Ariffin ◽  
Meor Iqram Meor Ahmad ◽  
Shahrum Abdullah ◽  
Wan Zulhelmi Wan Jusoh
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Testing Machine ◽  
Ferromagnetic Material ◽  
Magnetic Flux Leakage ◽  
Magnetic Memory ◽  
Tensile Testing Machine ◽  
Potential Possibility ◽  
Crack Position ◽  
Flux Leakage

In this paper, metal magnetic memory (MMM) method is used to detect the micro-crack position on the ferromagnetic material due to the fatigue process by determining to the stress concentration zones in the metal surfaces. The MMM method was carried out on mild steel using Instron 8874 universal tensile testing machine with different values of the ultimate tensile strength (UTS) varies from 75%, 80% and 85% until the specimens fails. An equipment of stress concentration indicator was used to measure the magnetic flux leakage, Hp patterns in the specimens. The results indicated that the position of a crack on the specimen that failed due to fatigue test was correlated with the scanning interval from the magnetic flux leakage signals. Therefore, the MMM method provides the potential possibility to detect the position of fatigue damage or defect in the metal components.

scholarly journals Magnetic field gradient as the most useful signal for detection of flaws using MFL technique

2018 ◽  
Vol 69 (6) ◽  
pp. 422-425 ◽  
Author(s):  
Zbigniew Usarek ◽  
Marek Chmielewski ◽  
Leszek Piotrowski
Keyword(s):  
Magnetic Flux ◽  
Steel Plate ◽  
Magnetic Field Gradient ◽  
Normal Component ◽  
Magnetic Flux Leakage ◽  
Magnetic Flux Density ◽  
Scanning Velocity ◽  
Useful Signal ◽  
Flux Leakage ◽  
Proper Analysis

Abstract The magnetic flux leakage (MFL) technique is extensively used for detection of flaws as well as for evaluation of their dimensions in ferromagnetic materials. However, proper analysis of the MFL signal is hindered by the MFL sensor velocity causing distortions of this signal. Traditionally measured components of the MFL signal are particularly sensitive to the scanning velocity. In this paper, an another signal – the gradient of the normal component of magnetic flux density – was proposed as it is less sensitive to the scanning velocity. Results obtained for scans of the steel plate with artificially manufactured flaws confirm this statement.

Stress Induced Self Magnetic Flux Leakage at Stress Concentration Zone

2021 ◽  
pp. 1-1
Author(s):  
Mehrdad Kashefi ◽  
Lynann Clapham ◽  
Thomas W. Krause ◽  
P. Ross Underhill ◽  
Anthony K. Krause
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Magnetic Flux Leakage ◽  
Stress Concentration Zone ◽  
Concentration Zone ◽  
Flux Leakage

Effect of Stress Concentration on Magnetic Flux Leakage Signals from Blind-Hole Defects in Stressed Pipeline Steel

1996 ◽  
Vol 8 (1) ◽  
pp. 83-100 ◽  
Author(s):  
T. W. Krause ◽  
R. W. Little ◽  
R. Barnes ◽  
R. M. Donaldson ◽  
B. Ma ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Pipeline Steel ◽  
Magnetic Flux Leakage ◽  
Blind Hole ◽  
Hole Defects ◽  
Flux Leakage

Effect of Stress Concentration on Magnetic Flux Leakage Signals from Blind-Hole Defects in Stressed Pipeline Steel

1996 ◽  
Vol 8 (2) ◽  
pp. 83-100 ◽  
Author(s):  
T. W. Krause ◽  
R. W. Little ◽  
R. Barnes ◽  
R. M. Donaldson ◽  
B. Ma ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Magnetic Flux ◽  
Pipeline Steel ◽  
Magnetic Flux Leakage ◽  
Blind Hole ◽  
Hole Defects ◽  
Flux Leakage

Investigating the Relative Severity of Dents in Pipelines Based on Magnetic Flux Leakage Inspection Data

2008 ◽  
Author(s):  
Leanne M. Tindall ◽  
Julia M. Race ◽  
Jane Dawson
Keyword(s):  
Magnetic Flux ◽  
Impact Damage ◽  
Fatigue Loading ◽  
Third Party ◽  
Magnetic Flux Leakage ◽  
Inspection Data ◽  
Pipeline Failures ◽  
Pipeline Safety ◽  
Flux Leakage ◽  
Dent Depth

Dent damage in pipelines may result from either impact damage caused by third parties or construction damage. Third party damage generally occurs on the upper half of the pipe (between the 8 o’clock and 4 o’clock positions) and has historically contributed to the highest number of pipeline failures. Dents caused during construction generally occur on the bottom half of the pipe and tend to be constrained by the indenter causing the dent, i.e. a stone or rock in the pipeline bed/backfill. However, all dents have the potential to cause an increase in stress in the pipeline, and consequently increase the pipeline sensitivity to both static and fatigue loading. Although there are extensive recommendations for the ranking and repair of dents, recently, failures of dents that are acceptable to pipeline codes have been reported. Guidance is therefore needed in order that operators can identify dents for which excavation and inspection is uneconomic and could potentially be damaging to pipeline safety and dents for which further action is required. This paper provides a review of the published recommendations for the treatment of pipeline dents and goes on to present a method that is being developed to determine the relative severity of dents in a pipeline using magnetic flux leakage (MFL) signal data. The proposed method involves measuring MFL signal parameters related to the geometry of the dent and relating these to high resolution caliper inspection data. This analysis enables a relationship to be established between the MFL signal data and dent depth and shape measurements. Once the model is verified, this analysis can then be used to provide a severity ranking for dents on pipelines where only MFL data is available.

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