Three-Dimensional Identification of Semi-Elliptical Crack on the Back Surface by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor (PVP2006-ICPVT-11-93359)

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Naoya Tada ◽  
Akira Funakoshi
Keyword(s):  
Direct Current ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Elliptical Crack ◽  
Potential Difference ◽  
Back Surface ◽  
Electrical Potential Difference ◽  
Multiple Probe ◽  
Probe Sensor

Cracks are popular defects initiated in structural components and their accurate evaluation is very important to assure the reliability of various plants. The direct-current electrical potential difference method is known as one of the most effective methods for the evaluation of the cracks. In this paper, a method of three-dimensional identification of a semi-elliptical crack existing on the back surface of a conductive plate by the direct-current electrical potential difference method with a multiple-probe sensor is proposed. The geometrical condition of the crack was specified by six parameters, the surface and inward angles of the crack plane, θsur and θin, the length and depth of the crack, c and a, and the two-dimensional location of the crack center, (yc,zc), on the back surface. The identification was carried out based on the distribution of electrical potential difference on the surface of the plate measured with a sensor composed of grid-arranged multiple probes called the “multiple-probe sensor.” As an approximate cracked body and a quick analysis method were used, a number of repeated electrical potential field analyses necessary for the identification of the crack became possible within a practical time. The validity of the method was numerically confirmed by carrying out the identification based on the result of the finite element analysis. The proposed method could be extended to the online monitoring of a semi-elliptical crack initiated on the inner surface of tubular components by means of the multiple-probe sensor placed on the outer surface.

Three-Dimensional Identification of Semi-Elliptical Crack on the Back Surface by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor

2006 ◽  
Author(s):  
Naoya Tada ◽  
Akira Funakoshi
Keyword(s):  
Direct Current ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Elliptical Crack ◽  
Potential Difference ◽  
Back Surface ◽  
Electrical Potential Difference ◽  
Multiple Probe ◽  
Probe Sensor

A method of three-dimensional identification of a semi-elliptical crack existing on the back surface of a conductive plate by direct-current electrical potential difference method with a multiple-probe sensor was proposed. The geometrical condition of the crack was specified by six parameters, the surface and inward angles of the crack plane, θsur and θin, the length and depth of the crack, c and a, and the two-dimensional location of the crack center, (yc, zc), on the back surface, respectively. Identification was carried out based on the distribution of electrical potential difference on the surface of the plate measured with a sensor composed of grid-arranged multiple probes called the “multiple-probe sensor.” As an approximate cracked body and a quick analysis method were used, a number of repeated electrical potential field analyses necessary for the identification of the crack became possible within a practical time. The validity of the method was numerically confirmed by carrying out the identification based on the result by the finite element analysis.

Three-Dimensional Identification of Semi-Elliptical Surface Crack by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor

2006 ◽  
Vol 129 (3) ◽  
pp. 441-448 ◽  
Author(s):  
Naoya Tada ◽  
Masayoshi Okada ◽  
Jun Iwamoto
Keyword(s):  
Direct Current ◽  
Surface Crack ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Crack Plane ◽  
Multiple Probe ◽  
Probe Sensor

A method of three-dimensional identification of a semi-elliptical surface crack by direct-current electrical potential difference method with a multiple-probe sensor was proposed and its validity was numerically examined. The condition of the surface crack embedded in a conductive plate was specified by the two-dimensional location of the crack center, length, and depth of the crack, and the surface and inward angles of the crack plane. Identification was carried out based on the distribution of the electrical potential difference around the crack measured on the surface of the plate with the “multiple-probe sensor” which is composed of many probes aligned in two orthogonal directions. The location and surface angle were evaluated using the point symmetry of the potential difference distribution. The inward angle was determined by the magnitude of symmetry of potential difference distribution with reference to the evaluated crack line. Finally, length and depth of the crack were determined using the exact solution of potential difference for an inclined inner elliptical crack which yields similar potential difference to that of the inclined semi-elliptical surface crack. The validity of the method was numerically confirmed by carrying out the evaluation based on the result obtained by finite element analysis.

Experimental Study of Three-Dimensional Identification of Semi-Elliptical Crack on the Back Surface by Means of Direct-Current Electrical Potential Difference Method of Multiple-Point Measurement Type

2007 ◽  
Author(s):  
Naoya Tada ◽  
Makoto Uchida ◽  
Akira Funakoshi ◽  
Hiroki Ishikawa
Keyword(s):  
Direct Current ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Elliptical Crack ◽  
Potential Difference ◽  
Back Surface ◽  
Multiple Point ◽  
Electrical Potential Difference ◽  
Point Measurement

A method for identification of a semi-elliptical crack existing on the back surface of the material by means of direct-current electrical potential difference method of multiple-point measurement type was proposed. The geometry of the crack was given by the two-dimensional location of the crack center, the surface and inward angles of the crack, and the length and depth of the crack. The identification was carried out based on the distribution of potential difference on the surface. The related experiments were carried out using six metal plates with various semi-elliptical cracks made on the back surface by electric discharge machining. The geometry of the crack was successfully identified by the proposed method and the results were discussed.

Numerical Simulation for Identification of Semi-Elliptical Crack on the Inner Surface of Pipe by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor

2009 ◽  
Author(s):  
Naoya Tada ◽  
Makoto Uchida ◽  
Hiroki Ishikawa
Keyword(s):  
Direct Current ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Elliptical Crack ◽  
Potential Difference ◽  
Back Surface ◽  
Electrical Potential Difference ◽  
Current Path ◽  
Inner Surface

The direct-current potential difference method (DC-PDM) is known as one of the promising non-destructive methods to evaluate the crack in the conductors. This method utilizes the change in the current path or the potential difference which is caused by the crack. In the previous study, a method of three-dimensional evaluation of semi-elliptical crack on the back surface of plate was proposed and its theoretical validity and practical utility were shown based on the results of numerical analyses and experiments. In this study, the method is extended to the identification of semi-elliptical crack on the inner surface of pipe and the related electric field analyses are carried out by the finite element method. The results show that the crack on the inner surface of pipe can be evaluated by the proposed method based on the distribution of potential difference measured on the outer surface of pipe. The present extension will be very useful for various practical cases which are often seen in the piping of power-generating and petrochemical plants.

Three-Dimensional Identification of Semi-Elliptical Surface Crack by Means of Direct-Current Electrical Potential Difference Method With Multiple-Probe Sensor

2004 ◽  
Author(s):  
Naoya Tada ◽  
Masayoshi Okada ◽  
Jun Iwamoto
Keyword(s):  
Direct Current ◽  
Surface Crack ◽  
Difference Method ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Crack Plane ◽  
Multiple Probe ◽  
Probe Sensor

A method of three-dimensional identification of a semi-elliptical surface crack by direct-current electrical potential difference method with a multiple-probe sensor was proposed and its validity was numerically examined. The condition of the surface crack embedded in a conductive plate was specified by the two-dimensional location of the crack center, (yc, zc), length and depth of the crack, c and a, and the surface and inward angles of the crack plane, θsur and θin. Identification was carried out based on the distribution of the electrical potential difference around the crack measured on the surface of the plate with the “multiple-probe sensor” which is composed of many probes aligned in two orthogonal directions. The location, (yc, zc), and surface angle, θsur, were evaluated using the line and point symmetries of the potential difference distribution. The inward angle, θin, was determined by the magnitude of symmetry of potential difference distribution with reference to the evaluated crack line. Finally, length and depth of the crack, c and a, were determined using the exact solution of potential difference for an inclined inner elliptical crack which yields similar potential difference to that of the inclined semi-elliptical surface crack. The validity of the method was numerically confirmed by carrying out the evaluation based on the result obtained by finite element analysis.

Experimental Study of Three-Dimensional Identification of Semi-Elliptical Crack on the Back Surface by Means of Direct-Current Electrical Potential Difference Method of Multiple-Point Measurement Type

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Naoya Tada ◽  
Makoto Uchida ◽  
Akira Funakoshi ◽  
Hiroki Ishikawa
Keyword(s):  
Direct Current ◽  
Difference Method ◽  
Electrical Potential ◽  
Elliptical Crack ◽  
Potential Difference ◽  
Back Surface ◽  
Multiple Point ◽  
Geometrical Parameters ◽  
Electrical Potential Difference ◽  
Point Measurement

A method for identification of a semi-elliptical crack on the back surface of metal plate by means of direct-current electrical potential difference method (DC-PDM) of multiple-point measurement type was proposed by the authors previously. Geometry of the crack was given by the two-dimensional location of the crack center, the surface and inward angles of the crack, and the length and depth of the crack. In this paper, experiments on the crack identification were carried out using six metal plates with different geometries of semi-elliptical cracks made on the back surface by electric discharge machining. Geometrical parameters of the crack were evaluated by the proposed method. The result of identification was successful and it was clarified that the semi-elliptical crack on the back surface can be identified nondestructively by dc-PDM of multiple-point measurement type.

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