scholarly journals Measuring the depth of surface cracks using alternating current potential drop technique, with suppression of the influence of the electromagnetic properties of the metal

2021 ◽  
Vol 2091 (1) ◽  
pp. 012047
Author(s):  
P N Shkatov
Keyword(s):  
Crack Depth ◽  
Potential Drop ◽  
Alternating Current ◽  
Measurement Range ◽  
Electromagnetic Properties ◽  
Surface Cracks ◽  
Measuring Techniques ◽  
Drop Technique ◽  
Current Potential

Abstract Traditional measuring techniques often lead to errors due to the need to register signals in both defective and defect-free areas. In this paper, we introduce an alternating current potential drop technique with detuning from the influence of variations in the electromagnetic properties of the metal achieved by registering a signal only at the defective site. We show that, with an appropriate choice of measurement parameters, the use of the proposed technique leads to an increase in sensitivity to the crack depth as well as to an increase in the measurement range.

Influence of crack length on crack depth measurement by an alternating current potential drop technique

2010 ◽  
Vol 21 (10) ◽  
pp. 105702 ◽  
Author(s):  
Manoj K Raja ◽  
S Mahadevan ◽  
B P C Rao ◽  
S P Behera ◽  
T Jayakumar ◽  
...  
Keyword(s):  
Crack Length ◽  
Crack Depth ◽  
Potential Drop ◽  
Alternating Current ◽  
Depth Measurement ◽  
Crack Depth Measurement ◽  
Drop Technique ◽  
Current Potential

scholarly journals Inner defect depth detection using a multifrequency alternating current potential drop technique

AIP Advances ◽  
2016 ◽  
Vol 6 (10) ◽  
pp. 105312 ◽  
Author(s):  
Fangji Gan ◽  
Yuting Li ◽  
Zhengjun Wan ◽  
Junbi Liao
Keyword(s):  
Potential Drop ◽  
Alternating Current ◽  
Defect Depth ◽  
Drop Technique ◽  
Current Potential ◽  
Depth Detection

scholarly journals Multidirectional Alternating Current Potential Drop Technique for Detecting Random Cracks

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 76640-76645
Author(s):  
Wenyang Li ◽  
Fangji Gan ◽  
Shiping Zhao ◽  
Yongjie Zhou ◽  
Xiaoming He
Keyword(s):  
Potential Drop ◽  
Alternating Current ◽  
Drop Technique ◽  
Current Potential

Alternating Current Potential Drop Technique to Detect Pit-to-Crack Transition

MRS Advances ◽  
2016 ◽  
Vol 1 (17) ◽  
pp. 1241-1246
Author(s):  
Xuejun Huang ◽  
Lun Yu ◽  
Ronald Ballinger
Keyword(s):  
Crack Initiation ◽  
Potential Drop ◽  
Transition Process ◽  
Alternating Current ◽  
Localized Corrosion ◽  
Critical Transition ◽  
Total Lifetime ◽  
Crack Transition ◽  
Drop Technique ◽  
Current Potential

ABSTRACTPitting and localized corrosion can occur under various conditions and accelerate the subsequent cracking and the failure of a component. Pit-to-crack transition is considered a critical transition process and has a significant impact on the total lifetime of a component. In this study, an alternating current potential drop (ACPD) system is built and applied the detection of the pit-to-crack transition. The results show that the ACPD system is capable and sensitive to crack initiation and that the sensitivity increased with increased frequency. Crack initiation sites from pits are characterized and discussed.

scholarly journals Novel Method for Sizing Metallic Bottom Crack Depth Using Multi-frequency Alternating Current Potential Drop Technique

2015 ◽  
Vol 15 (5) ◽  
pp. 268 ◽  
Author(s):  
Yuting Li ◽  
Fangji Gan ◽  
Zhengjun Wan ◽  
Junbi Liao ◽  
Wenqiang Li
Keyword(s):  
Crack Depth ◽  
Potential Drop ◽  
Alternating Current ◽  
Element Analysis ◽  
Metal Structures ◽  
Voltage Ratio ◽  
Simulation And Experiment ◽  
Novel Method ◽  
Shallow Crack ◽  
Current Potential

Abstract Potential drop techniques are of two types: the direct current potential drop (DCPD) technique and alternating current potential drop (ACPD) technique, and both of them are used in nondestructive testing. ACPD, as a kind of valid method in sizing metal cracks, has been applied to evaluate metal structures. However, our review of most available approaches revealed that some improvements can be done in measuring depth of metal bottom crack by means of ACPD, such as accuracy and sensitivity of shallow crack. This paper studied a novel method which utilized the slope of voltage ratio-frequency curve to solve bottom crack depth by using a simple mathematic equation based on finite element analysis. It is found that voltage ratio varies linearly with frequency in the range of 5-15 Hz; this range is slightly higher than the equivalent frequency and lower than semi-permeable frequency. Simulation and experiment show that the novel method can measure the bottom crack depth accurately.

DC Potential Drop Technique Selecting Probes Distances Properly for Sizing Deep Surface Cracks

2005 ◽  
Author(s):  
Fumio Takeo ◽  
Masumi Saka ◽  
Seiichi Hamada ◽  
Manabu Hayakawa
Keyword(s):  
Power Plants ◽  
Potential Drop ◽  
Small Crack ◽  
Surface Cracks ◽  
Structural Components ◽  
Deep Surface ◽  
Close Proximity ◽  
Current Input ◽  
Quantitative Nde ◽  
Drop Technique

D-C potential drop (DCPD) technique is a powerful tool for quantitative NDE of cracks. The technique using four probes which are in close proximity to each other has been proposed for NDE of surface cracks; that is the closely coupled probes potential drop (CCPPD) technique. It has been shown that the sensitivity of CCPPD technique to evaluate a small crack is enhanced significantly in comparison with the usual method. On the other hand, since CCPPD technique has been developed to evaluate a small crack sensitively, it is not fit to evaluate deep cracks which are sometimes found in the structural components of power plants. The objective of this study was to enhance the sensitivity of evaluating deep surface cracks. By extending the distance between current input and output probes, the change in potential drop with the change in the depth of deeper crack becomes large. But the voltage of potential drop becomes small to measure, because the current density in the material becomes low. The voltage of the potential drop can be increased by increasing the applying current, but the current would also be limited by the equipment or contacting probes. Then the way to select the appropriate distances between probes from the viewpoints of the sensitivity and the required current has been shown.

scholarly journals Development of a technique for the real-time determination of crack geometries in laboratory samples

2018 ◽  
Vol 165 ◽  
pp. 09004
Author(s):  
Thomas M Buss ◽  
James P Rouse ◽  
Christopher J Hyde ◽  
Seamus D Garvey
Keyword(s):  
Cross Sections ◽  
Voltage Drop ◽  
Crack Depth ◽  
Potential Drop ◽  
Alternating Current ◽  
Crack Size ◽  
Skin Depth ◽  
Electrical Potentials ◽  
Thin Skin ◽  
Thick Skin

Crack size determination using electrical potentials both in service and in the laboratory has been undertaken for many years. In the laboratory this has mainly concentrated on the measurement of crack depth, with either alternating current (AC) or direct current (DC) supplies. Some work to determine the varying depth along the width of cracks as an inspection tool of in service parts using mapping methods has been done. This has used both AC and DC utilising various models to understand the data recorded, in Alternating Current Potential Drop (ACPD) a range of frequencies have been used to give various skin depths. The resulting analyses have been grouped into two groups 'thin skin' and 'thick skin', in the thin skin case the skin depth is significantly smaller than the depth of the crack 1/10th of the crack depth whereas in the thick skin cases are for cases where skin depth is over this limit. Some work has been carried out to try and unify these two approaches. The work presented here looks to develop a method using variable frequency ACPD to resolve further information about cracks growing in laboratory specimens. A system has been developed to rapidly sweep a wide frequency band and record voltage drop across a crack or feature. A selection of steel samples with known geometries and features have been used to trial and benchmark the technique. These samples have a range of cross sections as well as machined features or a range of shapes and sizes to simulate a range of crack geometries. This work has been approximated using a 2D computational model. This has been done using a reduced thickness approach.

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