POTENTIAL DROP DATA INVERSION FOR CRACK DEPTH PROFILING

2008 ◽  
Author(s):  
G. Sposito ◽  
P. Cawley ◽  
P. B. Nagy ◽  
Donald O. Thompson ◽  
Dale E. Chimenti
Keyword(s):  
Crack Depth ◽  
Depth Profiling ◽  
Potential Drop ◽  
Data Inversion

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.

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.

Development of Crack Depth Indicator for Deep Surface Crack

2005 ◽  
Author(s):  
Manabu Hayakawa ◽  
Seiichi Hamada ◽  
Fumio Takeo ◽  
Masumi Saka
Keyword(s):  
Surface Crack ◽  
Power Plants ◽  
Crack Depth ◽  
Thermal Power ◽  
Potential Drop ◽  
Experimental Measurements ◽  
Deep Surface ◽  
New Type ◽  
Turbine Casing ◽  
Shallow Crack

Crack depth indicator using a direct current potential drop technique has been generally applied to the nondestructive inspection in the thermal power plants such as steam pipe and turbine casing. In this paper, the authors presented practical studies concerning the development of the advanced crack depth indicator for the deep surface crack. The authors have conducted experimental measurements using the customary crack depth indicator inspecting the fatigue pre-cracked plate specimens of some materials. The results showed that the crack depth indicator was effective to inspect the surface shallow crack, however, it was hardly applied to the deep crack. And the sensor of this equipment was found to be difficult to apply some practical conditions such as contact surfaces and mechanical designs of inspected structures. To get over the restrictions, the authors have developed a new type of crack depth indicator and sensor. The authors have conducted additional experimental measurements applying this equipment using some pre-cracked specimens such as plates and structural components of some materials.

Characterisation of backwall crack depth using the pulsed potential drop method

2020 ◽  
Vol 62 (9) ◽  
pp. 555-558
Author(s):  
Wenyang Li ◽  
Shiping Zhao ◽  
Fangji Gan
Keyword(s):  
Crack Detection ◽  
Crack Depth ◽  
Potential Drop ◽  
Pulsed Current ◽  
Frequency Range ◽  
Crack Monitoring ◽  
Aisi 1045 ◽  
Electrical Conductors ◽  
Large Frequency ◽  
Current Potential

The alternating current potential drop (ACPD) technique has been used for monitoring backwall cracks in electrical conductors. However, previous systems required too much labour when ACPD measurements were made over a large frequency range (1 Hz-10 kHz). In this paper, a pulsed potential drop (PPD) method is found to be superior, not only in efficiency and stability but also in accurate crack detection. The detected signal excited by the pulsed current appears to be more sensitive to depth variations and, therefore, can be used for estimating crack depth in PPD testing. Experiments have been performed on AISI 1045 plates with machined cracks; the results obtained from these tests show the feasibility of crack monitoring using the PPD method.

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

Improved Imaging of Fatigue Crack Profile in Thick Cruciform Samples Using Ultrasonic Phased Array Models

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
S. Alavudeen ◽  
C. V. Krishnamurthy ◽  
Krishnan Balasubramaniam ◽  
D. M. Pugazhendhi ◽  
G. Raghava ◽  
...  
Keyword(s):  
Phased Array ◽  
Fatigue Cracks ◽  
Crack Depth ◽  
Potential Drop ◽  
Subzero Temperature ◽  
Virtual Experiments ◽  
Physical Measurements ◽  
Ultrasonic Phased Array ◽  
Experimental Trials

The determination of depth profile of vertical fatigue cracks generated in thick cruciform samples using an ultrasonic phased array is investigated in this paper. The cracks were formed by conducting fatigue fracture test on two mild steel cruciform specimens of 135 mm thickness: one under room temperature and the other under subzero temperature (−70°C). A semi-elliptical surface starter notch of 2 mm width and more than 400 mm length was initially created in the specimens. Alternating current potential drop technique and phased array ultrasonic technique were attempted in order to determine the depth profiles of the starter notch as well as that of the crack. Virtual experiments carried out with a finite-difference time domain based numerical model were found to be advantageous in reducing actual experimental trials, facilitate an understanding of the echo signatures, and help assess the crack depth. The profiles of the crack and the notch were verified through destructive assay of the samples and subsequent dye penetrant assisted physical measurements.

Thickness Effect and Fatigue Crack Development in Welded T-Joints

1990 ◽  
Vol 112 (4) ◽  
pp. 341-351 ◽  
Author(s):  
R. Yee ◽  
D. J. Burns ◽  
U. H. Mohaupt ◽  
R. Bell ◽  
O. Vosikovsky
Keyword(s):  
Fatigue Crack ◽  
Crack Depth ◽  
Plate Thickness ◽  
Potential Drop ◽  
Thickness Effect ◽  
T Joints ◽  
Linear Elastic ◽  
Initiation And Propagation ◽  
Elastic Fracture ◽  
Fatigue Crack Development

The effect of section thickness on the fatigue life of welded plate-to-plate T-joints was studied experimentally and theoretically using various linear elastic fracture mechanics models. Fatigue crack depth and shape development were monitored using potential drop techniques, ink staining and beachmarking. These data are used to define initiation and propagation lives, and to show the importance of crack coalescence in the propagation phase. The effects of attachment plate thickness and weld geometry are also discussed.

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