The State-of-the-Art Surveys for Application of Metal Magnetic Memory Testing in Remanufacturing

2011 ◽  
Vol 301-303 ◽  
pp. 366-372 ◽  
Author(s):  
Yuan Liang Zhang ◽  
Di Zhou ◽  
Peng Sen Jiang ◽  
Hong Chao Zhang
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Residual Life ◽  
Fatigue Cracks ◽  
Research Work ◽  
Creep Damage ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Comprehensive Survey ◽  
Chinese Scholars

Metal magnetic memory（MMM） testing has been used in the residual life prediction of remanufacturing cores. The MMM testing is one of the most promising nondestructive testing methods for achieving early diagnosis on micro defects of remanufacturing cores. This method can not only detect the traditional macro-cracks, but also identify the micro-damage caused by stress concentration. The principle of MMM testing works in the conditions that without requiring of the external exciting magnetic field, the magnetic field distribution of the inspection surface is scanned and measured by means of magnetic mutation signals to find the possible existence of stress concentration and location of micro-cracks. This paper presents a state-of-art survey about MMM testing mechanism and application of MMM method in Russia, Britain, China and the other countries. It includes the applications of this method in power station turbine blade damage detection by Russia scholars, evaluating the gear creep damage by Polish scholars and detecting the stress concentration districts of the train wheels damaged parts by Chinese scholars. The paper also reports that Chinese scholars developed methods of using MMM testing to characterize initiating and growing of fatigue cracks, and applied this method for prediction of residual life of remanufacturing cores. Based on the comprehensive survey, this paper points out further trends of the research work in the area. The paper also points out that microscopic physical mechanism of the MMM phenomenon and application of MMM testing in defining the manufacturability of remanufacturing cores should be further studied. Introduction

Correlation Between Stress Concentration Degree and Residual Magnetic Field

2016 ◽  
Author(s):  
Sheng Bao ◽  
Ashri Mustapha ◽  
Huangjie Lou
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Tensile Tests ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Residual Magnetic Field ◽  
Concentration Degree ◽  
Qualitative Relationship ◽  
Ferromagnetic Steels

In this research, the correlation between the stress concentration degree and the residual magnetic field (RMF) of ferromagnetic steels is investigated. Tensile tests were carried out to measure the RMF signals on the surface of steel specimens with different stress concentration degrees. The effectivity of the metal magnetic memory (MMM) technique in defective specimens was investigated in comparison with a non-defective specimen. Analysis of the qualitative relationship between the stress concentration degree and the RMF components was subsequently performed on two types of defective specimens. The qualitative correlation between the planar distributions of the RMF components and the stress concentration degree was further studied. It was validated that both the RMF signal and its planar distribution are effective in characterizing the stress concentration degree. The results obtained in this research will be a complement to the MMM technique.

Stress Concentration Positions Determination of Ferromagnetic Material Based on Magnetic Test Method

2009 ◽  
Vol 417-418 ◽  
pp. 865-868
Author(s):  
Feng Yun Yu ◽  
Jing Chong Zhang
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Spontaneous Magnetization ◽  
Tensile Load ◽  
Test Point ◽  
Test Method ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Magnetic Intensity ◽  
The Magnetic Field

The magnetic field of ferromagnetic components under service load and geomagnetic field increases is induced by the residual magnetic induction and spontaneous magnetization. The stress concentration positions can be determination by detecting the magnetic field and the fracture can be avoided. The magnetic intensities of the demagnetized samples are tested by metal magnetic memory test method. By tensile test, the relationship between the magnetic memory signals and tensile load is studied, and the metal magnetic memory characteristics of the demagnetized samples under condition that the load keeps a fixed value are obtained. The test result indicates that the magnetic intensities of the samples change greatly after demagnetized; the change of the magnetic intensity of each test point are much different with different tensile displacement; in the later period of hardening phase and necking phase, the magnetic intensity about the side of the stress concentration positions increases along with the increasing of tensile displacement, however that of the other side decreases, that is the gradient of Fracture position increases obviously. Basing on this result by testing the parts of components emphatically where the fatigue failure and breakdown appear easily, the abrupt accident can be avoided.

Experimental Study of Magnetic Field Variation Induced in Ferromagnetic Materials

2013 ◽  
Vol 312 ◽  
pp. 402-405
Author(s):  
Yang Yong ◽  
Dong Sun ◽  
Jie Ji
Keyword(s):  
Magnetic Field ◽  
Plastic Region ◽  
Steel Specimen ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Magnetic Memory ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Metal Magnetic Memory ◽  
Stress Increase

The fatigue tests on 15CrMo steel specimen were carried out and the metal magnetic memory (MMM) signals were detected. The experiment shows that the magnetic signals of specimen contain the information of stress distribution in the material inside. Furthermore, the experimental results show that the magnetic signals increase initial while then decrease slightly with the stress increase from 0kN to 200kN. Though analysis the MMM signals induced by different tensile stress within the plastic region of the specimen, a simple model was derived. The experimental results are consistent with the calculated results based on the Jiles-Atherton model.

Eddy Current and Metal Magnetic Memory Testing Nondestructive Evaluation for Superficial Defects of Old Cylinder Barrel

2016 ◽  
Vol 850 ◽  
pp. 107-112
Author(s):  
Chang Liang Shi ◽  
Shi Yun Dong ◽  
Wei Xue Tang ◽  
Hao Zhan
Keyword(s):  
Stress Concentration ◽  
Eddy Current ◽  
Eddy Current Testing ◽  
Magnetic Memory ◽  
Memory Testing ◽  
Metal Magnetic Memory ◽  
Current Testing ◽  
Cylinder Barrel ◽  
Metal Magnetic Memory Testing

Eddy current testing and metal magnetic memory testing, cooperated with special testing devices, were applied to detect the superficial defects of old cylinder barrel. It was indicated that there were three types of the signals, which were non-defect signals, discontinuous peak signals and continuous peak signals. Non-defect signals indicated that there was no defect in cylinder barrel, and the discontinuous peak signals denoted that there was circumferential cracking, and the continuous peak signals showed that there was longitudinal cracking in the surface of cylinder barrel. The amplitude of eddy current testing signals characterizes the depth of cracking, and the gradient of magnetic signals descript the degree of stress concentration. The method mentioned above detects the cracking and stress concentration in the superficial coat of old cylinder barrel, which effectively guarantee the quality of automobile cylinder.

Characterization of Crack Initiation Life in Ferromagnetic Material by Metal Magnetic Memory Testing

2015 ◽  
Vol 817 ◽  
pp. 791-796
Author(s):  
Chang Liang Shi ◽  
Wei Xue Tang ◽  
Hao Zhan ◽  
Shi Yun Dong
Keyword(s):  
Magnetic Field ◽  
Crack Initiation ◽  
Normal Component ◽  
Ferromagnetic Material ◽  
Magnetic Memory ◽  
Memory Testing ◽  
Metal Magnetic Memory ◽  
Numerical Fitting ◽  
Crack Initiation Life ◽  
Metal Magnetic Memory Testing

In the geomagnetic field, stress can induce spontaneous magnetic signals in ferromagnetic materials, the method, named metal magnetic memory testing, can be potentially applied in estimating the fatigue life. In this paper, the normal component of magnetic field, Hp (y), was measured during dynamic tension test on the surfaces of ferromagnetic specimens with stress concentration factor of 5. The results indicated that the gradient of magnetic field intensity, K, was the key parameter to characterize crack initiation life. Then the numerical fitting of K and fatigue cycles were done under three level loads, 568.7MPa, 698.8MPa and 864.4MPa, meanwhile, a simple model was derived.

Application Study of Metal Magnetic Memory Testing in the Q345E Steel Weld Inspection

2013 ◽  
Vol 273 ◽  
pp. 609-613
Author(s):  
Peng Lin Zhang ◽  
Wen Ke Wang ◽  
Yan Ping Wang ◽  
Li Cao
Keyword(s):  
Stress Concentration ◽  
Close Relation ◽  
Magnetic Memory ◽  
Memory Testing ◽  
Metal Magnetic Memory ◽  
Application Study ◽  
Testing Method ◽  
Weld Inspection ◽  
Nondestructive Testing Method ◽  
Metal Magnetic Memory Testing

Metal magnetic memory testing is a new nondestructive testing method and used to diagnose ferromagnetic components stress concentration. Welding defects and stress concentration has the close relation. This paper used metal magnetic memory in the weld inspection to study an effective weld magnetic memory testing method, at the same time to verify the results by X-ray inspection.

Metal Magnetic Memory Signal Analysis Based on EMD Method

2013 ◽  
Vol 804 ◽  
pp. 244-247
Author(s):  
Xia Yu ◽  
Jun Feng Fan ◽  
Wei Ming Zhang ◽  
Zhong Chao Qiu
Keyword(s):  
Stress Concentration ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Intrinsic Mode Functions ◽  
Model Decomposition ◽  
Noise Interference ◽  
Reconstructed Signal ◽  
Original Metal ◽  
Gmr Sensor ◽  
Emd Method

In order to determine stress concentration zones and defects on the surface of ferromagnetic components, the empirical model decomposition (EMD) method was proposed to eliminate noise interference of metal magnetic memory signal. Tensile-tensile fatigue test of 16MnR steel with prefabricated defects were carried out, and magnetic signals were measured using GMR sensor. The original metal magnetic memory signal was first decomposed into different intrinsic mode functions (IMF) and a residue, and reconstructed signal was obtained on the basis of the degree of the correlation coefficient. Results indicate that the reconstruction signal displays the maxima at 30mm, and there is a good correlation between the real maxima and the stress concentration zone. The EMD method is a effective signal processing method about magnetic memory signal containing some interference factors.

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