Simulation and Analysis on the Best Range of Lift-Off Values in MFL Testing

2013 ◽  
Vol 321-324 ◽  
pp. 811-814 ◽  
Author(s):  
De Hui Wu ◽  
Zhong Yuan Zhang ◽  
Zhen Liang Liu ◽  
Xiao Hao Xia
Keyword(s):  
Mechanical Vibration ◽  
Fem Simulation ◽  
Near Surface ◽  
Testing Method ◽  
Surface Areas ◽  
Field Peak ◽  
Lift Off ◽  
Nondestructive Testing Method ◽  
Strength Of Excitation ◽  
Flux Leakage

As a nondestructive testing method, the magnetic flux leakage (MFL) testing technique is widely used for the testing of surface and near-surface areas in ferromagnetic materials. The MFL field is influenced by parameters of defects, strength of excitation, sensor lift-off value and electromagnetic noises etc. A 2-D finite element method (FEM) simulation model is established in this paper to analyze the influence of lift-off values under the condition of mechanical vibration and electromagnetic noises. The distribution of the MFL field peak for different lift-off values and different depth defects is presented. The defect quantization errors caused by the mechanical vibration and electromagnetic noises are introduced to analyze the influence of lift-off values and electromagnetic noises. The best range of lift-off values can be determined from the results of error analysis. It is effective to improve the measuring accuracy in practical MFL testing.

scholarly journals A Lift-Off-Tolerant Magnetic Flux Leakage Testing Method for Drill Pipes at Wellhead

Sensors ◽  
2017 ◽  
Vol 17 (12) ◽  
pp. 201 ◽  
Author(s):  
Jianbo Wu ◽  
Hui Fang ◽  
Long Li ◽  
Jie Wang ◽  
Xiaoming Huang ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Magnetic Flux Leakage ◽  
Testing Method ◽  
Drill Pipes ◽  
Lift Off ◽  
Flux Leakage ◽  
Magnetic Flux Leakage Testing

scholarly journals Magnetic Flux Leakage Course of Inner Defects and Its Detectable Depth

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jianbo Wu ◽  
Wenqiang Wu ◽  
Erlong Li ◽  
Yihua Kang
Keyword(s):  
Magnetic Flux ◽  
Steel Structure ◽  
High Sensitivity ◽  
Magnetic Flux Leakage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Near Surface ◽  
Testing Method ◽  
Non Destructive ◽  
Flux Leakage

AbstractAs a promising non-destructive testing (NDT) method, magnetic flux leakage (MFL) testing has been widely used for steel structure inspection. However, MFL testing still faces a great challenge to detect inner defects. Existing MFL course researches mainly focus on surface-breaking defects while that of inner defects is overlooked. In the paper, MFL course of inner defects is investigated by building magnetic circuit models, performing numerical simulations, and conducting MFL experiments. It is found that the near-surface wall has an enhancing effect on the MFL course due to higher permeability of steel than that of air. Further, a high-sensitivity MFL testing method consisting of Helmholtz coil magnetization and induction coil with a high permeability core is proposed to increase the detectable depth of inner defects. Experimental results show that inner defects with buried depth up to 80.0 mm can be detected, suggesting that the proposed MFL method has the potential to detect deeply-buried defects and has a promising future in the field of NDT.

Selective Area Deposition of Passivants, Insulators, and Epitaxial Films of II-VI Compound Semiconductors

1989 ◽  
Vol 161 ◽  
Author(s):  
D.L. Dreifus ◽  
Y. Lansari ◽  
J.W. Han ◽  
S. Hwang ◽  
J.W. Cook ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Epitaxial Films ◽  
Semiconductor Surface ◽  
Epitaxial Layers ◽  
Double Crystal ◽  
Surface Areas ◽  
Selective Area ◽  
Lift Off ◽  
P Type ◽  
Area Deposition

ABSTRACTII-VI semiconductor surface passivants, insulators, and epitaxial films have been deposited onto selective surface areas by employing a new masking and lift-off technique. The II-VI layers were grown by either conventional or photoassisted molecular beam epitaxy (MBE). CdTe has been selectively deposited onto HgCdTe epitaxial layers as a surface passivant. Selective-area deposition of ZnS has been used in metal-insulator-semiconductor (MIS) structures. Low resistance ohmic contacts to p-type CdTe:As have also been realized through the use of selectively-placed thin films of the semi-metal HgTe followed by a thermal evaporation of In. Epitaxial layers of HgTe, HgCdTe, and HgTe-CdTe superlattices have also been grown in selective areas on CdZnTe substrates, exhibiting specular morphologies and double-crystal x-ray diffraction rocking curves (DCXD) with full widths at half maximum (FWHMs) as narrow as 140 arcseconds.

Modified Edge Lift-Off Test: Experimental Modifications for Multifilm Systems

1999 ◽  
Vol 594 ◽  
Author(s):  
J. C. Hay ◽  
E. G. Liniger ◽  
X-H Liu
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Strain Energy ◽  
Plate Bending ◽  
Adhesion Test ◽  
Testing Method ◽  
Rate Calculation ◽  
Lift Off ◽  
Microelectronics Fabrication

AbstractIn developing an adhesion test for a microelectronics fabrication facility there are many criteria which must be met. Some of these include (i) sample prep must be simple, (ii) deformations should be elastic so the problem can be easily modeled, (iii) mechanics are ideally analytical, and (iv) the test end-point must be unambiguous and easy to obtain. A testing method in the literature which meets many of these criteria is the modified edge liftoff test (MELT). Delamination is induced through the release of strain energy stored in an elastic superlayer which results from a large mismatch in CTE between the film and substrate. In this work we consider details of the energy release rate calculation, effects of plate bending, and initial flaw size.

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