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Determining the potential drop calibration of a fatigue crack growth specimen subject to limited experimental observations
I~UTTERWORTH I~IE I N E M A N N
NDT&E International Voi. 28, No. 1, pp. 45-52, 1995 Elsevier Science Ltd Printed in Great Britain.
- N D T abstracts N D T A b s t r a c t s a r e c o m p i l e d b y A E A T e c h n o l o g y N a t i o n a l N D T C e n t r e , Harwell, O x o n , O X 1 1 0 R A , U K . T h e e n t r i e s are d r a w n f r o m o v e r 500 British a n d I n t e r n a t i o n a l p u b l i c a t i o n s . E a c h issue c o n c e n t r a t e s o n o n e o r t w o s u b j e c t areas. T h e subjects c o v e r e d in p r e v i o u s issues f r o m F e b r u a r y 1993 o n w a r d s are: Acoustic a n d u l t r a s o n i c m e a s u r e m e n t o f elastic constants - 27(1); Acoustic emission testing o f p r e s s u r e vessels - 26(6); C o n d i t i o n m o n i t o r i n g using a c o u s t i c a n d t h e r m a l techniques - 27(4) M a g n e t i c flux l e a k a g e - 26(1); M i c r o w a v e N D T - 27(6); N D T in r a i l w a y s - 26(4); N D T using b a e k s c a t t e r o f u l t r a s o u n d - 26(5); P o s i t r o n a n n i h i l a t i o n - 27(5); S y n t h e t i c a p e r t u r e signal processing - 26(3); T h e r m o g r a p h y o f c o m p o s i t e s - 26(2); U l t r a s o n i c N D E o f a i r c r a f t - 27(3); X - r a y t o m o g r a p h y - 27(2)
Potential drop techniques 56319 Ghajarieh, R.: Saka, M.; Sugawara, T.: Abe, H.; Komura. L: Sakamoto, H.
55615 Shkatov, P~I. Methodological and instrumental errors in electropotential
NDE of multiple cracks on the surface of materials by means of the potential drop technique NDT&E International, Vol. 27, No. 3, pp. 143-150 (Jun. 1994) A method is developed to evaluate nop~._.structivelymultiple cracks on the surface of materials. The method is based on the d.c. potential drop technique. Multiple two-dinwamional cracks of unknown depth are inspected, whexe the distance between the cracks is known. First the distribution of the potential drop between both sides of each crack is measured on the cracked s u f f a ~ Next the distribution of the potential drop is calculated numerically by assuming the depth of every crack. Then by comparing the measured and calculated potential drop, a correction factor is obtained for t ~ assumed depth of the respective cracks. Modifying the crack depth by the correction factor is repeated until the difference between the measured and calculated distributions of the potential drop is minimized. it is shown that multiple cracks are sized accurately by the present method.
crack depth measurement Russian Journal of Nondestructive Testing, Vol. 29, No. 8, pp. 626-630 (Apr. 1994) An analysis is presented for the error in measuring the depth of a surface crack by the electric potential method, particularly as arising in interpreting the effects of the crack length and thickness variation. The variation in the instrumental error has been determined as a function of electrode separation, which is associated with the inaccuracy in recording the voltages. This enables one to correct for crack length and workplece thickness for a given combination of these pmmnew~ while the approach enables one to optimize the sensor parameten. 54775 Saka. M.; Yuasa, D.; Abe, H.; Sugino, K.: Kageyama. H. Potential drop technique for nondestructive evaluation of bifurcated crack in rail Nondestructive Testing and Evaluation, Vol. 10, No. 6, pp. 333-341 (1993) The potential drop technique was applied to nondestructive evaluation of a crack bifurcated downwards from a non-planar crack in a rail, since the case of non-planar cracks is more often observed than that of horizontal cracks. The method of evaluation was based on the measurement of the dis~ibution of d.c, elec~cai potential on the top surface of the rail. A problem of current flow in a plate, which contained non-planar and bifu~_!e4 cracks modelled in practical shape and was subjected to a uniform current, was analyzed numerically by using a 2-D finite element method. The potential distribution on the measuring surface of the plate was
55788 Grimberg, R.; Andreescu, A.; Savin, A. Modern methods of non.destructive testing (In Romanian; English abstract) Simpozionui Asociatiei Romane de Enaminari Nedistructive, Hunedoara (Romania), 11-13 May 1994. Vol. I-A, pp. 184-192. ARoENd (1994) Taking advantage of the modern facilities of information put at our disposal by the British Institute of Non-desm~ve Testing and the National Centre of Non-desltuctive Testing HanOI, the authors review some new e ~ c methods of nondesU-uetive testing such as: alternative
obtained for various combinations of the cracks.
current potential drop (ACPD), alternative current field measurement (ACFM), remote field eddy current inspection, directions of inquiry and probable applications of these methods of testing.
55787 McKeighan, P.C.; Smith. DJ. Determining the potential drop calibration of a fatigue crack growth specimen subject to limited experimental observations Journal of Testing Evaluation, Vol. 22, No. 4, pp. 291-301 (Jui. 1994) Six separate calibration techniques are applied to potential drop (PD) and crack length data from 23 experimental datasets. Five of the techniques use limited experimental input gained during precn~ing and after test completion to derive the coefficients assecia!~ with the calibrations. The datasets include SE(B) and M(T) specimens, fatigue crack growth (FCG) tests and foil analog simulations as well as various aluminum alloys and steel. A comparison of the calibration techniques is undertaken in terms of
53782 Oppermann,W.: Keller. H.P. An improved potential drop method for measuring a n d monitoring defects in metalfic structures Nuclear Engineering and Design, Vol. 144, No. 1, pp. 171-175 (1 Oct. 1993) In the developed form described the direct current potential drop method is a reliable and relatively accurate procedure for the measuring and surveillance of surface cracks in metallic materials. There are also significant possibilities in practice of surveying cracks on the inaccessible side of the structure. The basis for the improvement in accuracy, in particular for short cracks, is firstly an impreved measuring technique and secondly calibration curves determined using an electrolytic tank. Practical experience gained in conventional plants is to date positive. The opportunity exists of heuefitting from the advantages that would be brought about by an increased use of the potential drop method in plant surveillance. 53546 Harrington, D.S.; Bell, R. A mobile DCPD probe arrangement for improved crack profile measurements British Journal of Non-Destructive Testing, Voi. 35, No. 9, pp. 497501 (Sep. 1993)
crack length and the subsequent effect on stress intensity factor errors. The best calibration techniques using two PD and crack length data paris are the two-point modified and post- test corrected Johnson's equation.
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NDT&E International Voi. 28, No. 1, pp. 45-52, 1995 Elsevier Science Ltd Printed in Great Britain.
- N D T abstracts N D T A b s t r a c t s a r e c o m p i l e d b y A E A T e c h n o l o g y N a t i o n a l N D T C e n t r e , Harwell, O x o n , O X 1 1 0 R A , U K . T h e e n t r i e s are d r a w n f r o m o v e r 500 British a n d I n t e r n a t i o n a l p u b l i c a t i o n s . E a c h issue c o n c e n t r a t e s o n o n e o r t w o s u b j e c t areas. T h e subjects c o v e r e d in p r e v i o u s issues f r o m F e b r u a r y 1993 o n w a r d s are: Acoustic a n d u l t r a s o n i c m e a s u r e m e n t o f elastic constants - 27(1); Acoustic emission testing o f p r e s s u r e vessels - 26(6); C o n d i t i o n m o n i t o r i n g using a c o u s t i c a n d t h e r m a l techniques - 27(4) M a g n e t i c flux l e a k a g e - 26(1); M i c r o w a v e N D T - 27(6); N D T in r a i l w a y s - 26(4); N D T using b a e k s c a t t e r o f u l t r a s o u n d - 26(5); P o s i t r o n a n n i h i l a t i o n - 27(5); S y n t h e t i c a p e r t u r e signal processing - 26(3); T h e r m o g r a p h y o f c o m p o s i t e s - 26(2); U l t r a s o n i c N D E o f a i r c r a f t - 27(3); X - r a y t o m o g r a p h y - 27(2)
Potential drop techniques 56319 Ghajarieh, R.: Saka, M.; Sugawara, T.: Abe, H.; Komura. L: Sakamoto, H.
55615 Shkatov, P~I. Methodological and instrumental errors in electropotential
NDE of multiple cracks on the surface of materials by means of the potential drop technique NDT&E International, Vol. 27, No. 3, pp. 143-150 (Jun. 1994) A method is developed to evaluate nop~._.structivelymultiple cracks on the surface of materials. The method is based on the d.c. potential drop technique. Multiple two-dinwamional cracks of unknown depth are inspected, whexe the distance between the cracks is known. First the distribution of the potential drop between both sides of each crack is measured on the cracked s u f f a ~ Next the distribution of the potential drop is calculated numerically by assuming the depth of every crack. Then by comparing the measured and calculated potential drop, a correction factor is obtained for t ~ assumed depth of the respective cracks. Modifying the crack depth by the correction factor is repeated until the difference between the measured and calculated distributions of the potential drop is minimized. it is shown that multiple cracks are sized accurately by the present method.
crack depth measurement Russian Journal of Nondestructive Testing, Vol. 29, No. 8, pp. 626-630 (Apr. 1994) An analysis is presented for the error in measuring the depth of a surface crack by the electric potential method, particularly as arising in interpreting the effects of the crack length and thickness variation. The variation in the instrumental error has been determined as a function of electrode separation, which is associated with the inaccuracy in recording the voltages. This enables one to correct for crack length and workplece thickness for a given combination of these pmmnew~ while the approach enables one to optimize the sensor parameten. 54775 Saka. M.; Yuasa, D.; Abe, H.; Sugino, K.: Kageyama. H. Potential drop technique for nondestructive evaluation of bifurcated crack in rail Nondestructive Testing and Evaluation, Vol. 10, No. 6, pp. 333-341 (1993) The potential drop technique was applied to nondestructive evaluation of a crack bifurcated downwards from a non-planar crack in a rail, since the case of non-planar cracks is more often observed than that of horizontal cracks. The method of evaluation was based on the measurement of the dis~ibution of d.c, elec~cai potential on the top surface of the rail. A problem of current flow in a plate, which contained non-planar and bifu~_!e4 cracks modelled in practical shape and was subjected to a uniform current, was analyzed numerically by using a 2-D finite element method. The potential distribution on the measuring surface of the plate was
55788 Grimberg, R.; Andreescu, A.; Savin, A. Modern methods of non.destructive testing (In Romanian; English abstract) Simpozionui Asociatiei Romane de Enaminari Nedistructive, Hunedoara (Romania), 11-13 May 1994. Vol. I-A, pp. 184-192. ARoENd (1994) Taking advantage of the modern facilities of information put at our disposal by the British Institute of Non-desm~ve Testing and the National Centre of Non-desltuctive Testing HanOI, the authors review some new e ~ c methods of nondesU-uetive testing such as: alternative
obtained for various combinations of the cracks.
current potential drop (ACPD), alternative current field measurement (ACFM), remote field eddy current inspection, directions of inquiry and probable applications of these methods of testing.
55787 McKeighan, P.C.; Smith. DJ. Determining the potential drop calibration of a fatigue crack growth specimen subject to limited experimental observations Journal of Testing Evaluation, Vol. 22, No. 4, pp. 291-301 (Jui. 1994) Six separate calibration techniques are applied to potential drop (PD) and crack length data from 23 experimental datasets. Five of the techniques use limited experimental input gained during precn~ing and after test completion to derive the coefficients assecia!~ with the calibrations. The datasets include SE(B) and M(T) specimens, fatigue crack growth (FCG) tests and foil analog simulations as well as various aluminum alloys and steel. A comparison of the calibration techniques is undertaken in terms of
53782 Oppermann,W.: Keller. H.P. An improved potential drop method for measuring a n d monitoring defects in metalfic structures Nuclear Engineering and Design, Vol. 144, No. 1, pp. 171-175 (1 Oct. 1993) In the developed form described the direct current potential drop method is a reliable and relatively accurate procedure for the measuring and surveillance of surface cracks in metallic materials. There are also significant possibilities in practice of surveying cracks on the inaccessible side of the structure. The basis for the improvement in accuracy, in particular for short cracks, is firstly an impreved measuring technique and secondly calibration curves determined using an electrolytic tank. Practical experience gained in conventional plants is to date positive. The opportunity exists of heuefitting from the advantages that would be brought about by an increased use of the potential drop method in plant surveillance. 53546 Harrington, D.S.; Bell, R. A mobile DCPD probe arrangement for improved crack profile measurements British Journal of Non-Destructive Testing, Voi. 35, No. 9, pp. 497501 (Sep. 1993)
crack length and the subsequent effect on stress intensity factor errors. The best calibration techniques using two PD and crack length data paris are the two-point modified and post- test corrected Johnson's equation.
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