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Magnetic leakage fields calculated by the method of finite differences
T N D T Abstracts is a current awareness service compiled by the National N D T Centre AERE Harwell, Didcot, Oxon, OX11 0RA, UK. The entries are drawn from over 200 British and International publications. Each issue concentrates on one or two subject areas, and contains abstracts entered from 1987 to the present.
Magnetic testing techniques Goebbels, K. Surface crack detection by magnetic particle inspection (In Germanl 39304
M a t e r i a l p r u f u n g , Vol. 30, No. 10, pp. 327-332 (Oct. 1988) For ferromagnetic materials magnetic particle inspection is without doubt the most sensitive method to detect surface cracks and the least sensitive method referring to disturbing boundary conditions. Up to now the technique is based on experiments, experience, on empirical facts and on a subjective evaluation. This contribution for the first time presents a concept which allows objective, reproducible and reliable magnetic particle inspection: modelling of testing based on Maxwell's equations by finite element calculation; objective setting of test-parameters and their surveillance, handling systems, illumination and sensors, image processing and fully automated evaluation.
Kashiwaya, K.; Indue, Y.; Sakamoto, H. Development of magnetic anisotropy sensor for stress measurement on curved surface (In Japanese)
39303
J o u r n a l of the J a p a n e s e Society for N o n - D e s t r u c t i v e I n s p e c t i o n , Vol. 37, No. 8, pp. 618-623 ( A u g . 1988) A tripodic magnetic anistropy sensor has been developed for ramdestructive stress measurements on a curved surface. Each leg of the sensor comes at each apex of a right isosceles triangle and the shape of each toe is made a hemisphere in order to be able to contact any curved surface with the same condition. Fundamental experiments have been performed using cylindrical test pieces made of mild steel with various curvatures. This method makes stress measurement feasible on any curved surface, independent of curvature. Furthermore, stress measurements on the stress concentration area of an axle have been demonstrated in order to ensure the practical applicability of this method. The result indicates that the difference in principal stress is measurable to an accuracy of + 10 MPa with mild steel.
ltou, Y.; Obata, M.; Furuya, Y.; Shimada, H. Non-contact stress evaluation by Barkhausen noise method changing maximum magnetizing voltage (In Japanese) 39302
J o u r n a l of the J a p a n e s e Society for N o n - D e s t r u c t i v e I n s p e c t i o n , Vol. 37, No. 8, pp. 649-654 ( A u g . 1988) The purpose of this paper is to develop a new non-contact stress measurement method using magnetic Barkhausen Noise (BHN). Previously the authors applied the BHN to stress measurement using a contact-type sensor under constant magnetizing conditions. However, this method has one significant disadvantage. The BHN voltage is so sensitive to the distance between pick-up sensor and surface of specimen that it is difficult to measure the stress by the BHN under a non-contact condition. In an effort to realize a non-contact stress measurement by a BHN method, the authors compared the variation of the BHN voltage ( V / s u b BHN/) with the maximum magnetizing voltage (V/sub M/). It is discovered that (DELTAV/sub BHN//DELTAV/sub M/) strongly depends on the applied stress but is independent of the distance between a sensor and a specimen. It is found from this result that the stress can be measured even under non-contact conditions by the BHN method applying the parameter. DELTAV/sub BHN//DELTAV/sub M/.
Sanford-Francis, C.H.A. Safe service life availability from measurements of magnetic material change in metals 39301
B r i t i s h J o u r n a l of N o n - D e s t r u c t i v e Testing, Vol. 30, No. 5, pp. 342364 (Sep. 1988) This paper outlines a magnetic inspection procedure which measures the rate of material change in metals electromagnetically, precisely locating regions of fatigue damage early in the fatigue process, long before cracks develop in metal. Results show that changes in magnetic permeability can be used to predict failures in service so components can be withdrawn from service before breakdown. The procedure has proved simple and safe. 39146 Brudar, B. M a g n e t i c leakage fields calculated by the met.hod of finite differences P r o c e e d i n g s of the 4 t h E u r o p e a n C o n f e r e n c e o n N o n - D e s t r u c t i v e
54
Testing, L o n d o n ( U n i t e d K i n g d o m ) , 13-17 Sop. 1987. Vol. I. pp. 665-674. P e r g a m o n Press, 3173 pp. (1988) Magnetic leakage fields around a surface crack in a ferromagnetic matcriat have been measured and calculated on basis of simplified assumptions. In this article the detailed description of the necessary suppositions at specified mesh points in the numerical procedure (FD) is given, taking into account the dependence of the relative permeability on the magnetic field strength. 39145 Jiles, D.C. Review of magnetic methods for nondestructive evaluation N D T I n t e r n a t i o n a l , Vol. 21, No. 5, pp. 311-319 (Oct. 1988) This paper provides a guideline to the literature of magnetic techniques to~ nondestructive evaluation. Compared with other NDE methods such as ultrasonics or eddy currents, the literature for magnetic methods is relatively small, but one of the difficulties is that it is widely scattered. This review therefore presents a fairly comprehensive summary of works on Barkhauscn effect, magnetoacoustic emission, magnetic hysteresis, residual field and magnetically induced velocity change methods that have appeared to data 39144 Wang Yangsheng; Shi ttanmin; Yan~ Shuzi. Quantitative wire rope inspection N D T I n t e r n a t i o n a l , Vol. 21, No. 5, pp. 337-340 (Oct. 1988) This paper describes a complete system for inspecting wire ropes automatically. Obstacles to the development of such a system are analysed m detail, followed by a description of the hardware and software of the system The hardware uses 12 Hall effect sensors arranged in a circle around the wire rope. Signal analysis is based on a pattern recognifionapproach. Selection of the feature vector and the use of a trainable non-linear classifier arc described 39143 Anotl. Introduction to flaw detection during production by magnetoelastie testing using Barkhausen noise (In French) Q u a l i t e R e v u e P r a t i q u e de C o n t r o l e I n d u s t r i c l , No. 150, pp. 104-! I~! ( A p r . 1988) 39142 Kaplan, B.Z,; Rabinovici, R. Nondestructive evaluation of ferromagnetic 'magnetometer like' experimental arrangement
materials
by
a
J o u r n a l of N o n d e s t r u c t i v e E v a l u a t i o n . Vol. 6,, N o 2, pp. 73-80 (,hm. 1987 ) The paper presents experimental results regarding tbc influence ol mechanical stresses and thermal treatments on the Barkhausen noise anti magnetization characteristic of MolyPermanoy and MuMetal ferromagnetic samples. The samples are different in stress magnitude and localization and in their thermal history. The level of Barkhausen noise and the changes itl magnetization characteristic arc estimated by measuring the sensitivity and transduction gain of 'magnetometer like' coils configuratkms which employ the studied ferromagnetic samples as their nonlin~car ferromagnetic cores: The present method is unique in the sense that the two factors (one factor is related t~ the internal magnetic noise, and the other one is related to the form of the magnetic characteristic) arc obtained by employing a single relatively simple experimental arrangement. Various types of stresses, which arc different in magnitude and localization, become distinguishable one from the other, when considering their differential effects on the two factors. Se~vra/ possible experimental arrangements are shown. 39141 Ponomarev, Yu.F. Harmonic analysis of the magnetization of ferromagnets remagnetized by an AC field, with magnetic hysteresis taken into account. IV. Application to nondestructive inspection Soviet J o u r n a l of N o n d e s t r u c t i v e T e s t i n g , Vol. 23, No. 6, pp. 430-439 (Feb. 1988) The article analyzes the possibilities of using one harmonic of the secondary electromagnetic force (emf) for determining three magnetic characteristics of the inspected objects when families of special symmetric magnetic hysteresis
NDT International February 1989
Magnetic testing techniques Goebbels, K. Surface crack detection by magnetic particle inspection (In Germanl 39304
M a t e r i a l p r u f u n g , Vol. 30, No. 10, pp. 327-332 (Oct. 1988) For ferromagnetic materials magnetic particle inspection is without doubt the most sensitive method to detect surface cracks and the least sensitive method referring to disturbing boundary conditions. Up to now the technique is based on experiments, experience, on empirical facts and on a subjective evaluation. This contribution for the first time presents a concept which allows objective, reproducible and reliable magnetic particle inspection: modelling of testing based on Maxwell's equations by finite element calculation; objective setting of test-parameters and their surveillance, handling systems, illumination and sensors, image processing and fully automated evaluation.
Kashiwaya, K.; Indue, Y.; Sakamoto, H. Development of magnetic anisotropy sensor for stress measurement on curved surface (In Japanese)
39303
J o u r n a l of the J a p a n e s e Society for N o n - D e s t r u c t i v e I n s p e c t i o n , Vol. 37, No. 8, pp. 618-623 ( A u g . 1988) A tripodic magnetic anistropy sensor has been developed for ramdestructive stress measurements on a curved surface. Each leg of the sensor comes at each apex of a right isosceles triangle and the shape of each toe is made a hemisphere in order to be able to contact any curved surface with the same condition. Fundamental experiments have been performed using cylindrical test pieces made of mild steel with various curvatures. This method makes stress measurement feasible on any curved surface, independent of curvature. Furthermore, stress measurements on the stress concentration area of an axle have been demonstrated in order to ensure the practical applicability of this method. The result indicates that the difference in principal stress is measurable to an accuracy of + 10 MPa with mild steel.
ltou, Y.; Obata, M.; Furuya, Y.; Shimada, H. Non-contact stress evaluation by Barkhausen noise method changing maximum magnetizing voltage (In Japanese) 39302
J o u r n a l of the J a p a n e s e Society for N o n - D e s t r u c t i v e I n s p e c t i o n , Vol. 37, No. 8, pp. 649-654 ( A u g . 1988) The purpose of this paper is to develop a new non-contact stress measurement method using magnetic Barkhausen Noise (BHN). Previously the authors applied the BHN to stress measurement using a contact-type sensor under constant magnetizing conditions. However, this method has one significant disadvantage. The BHN voltage is so sensitive to the distance between pick-up sensor and surface of specimen that it is difficult to measure the stress by the BHN under a non-contact condition. In an effort to realize a non-contact stress measurement by a BHN method, the authors compared the variation of the BHN voltage ( V / s u b BHN/) with the maximum magnetizing voltage (V/sub M/). It is discovered that (DELTAV/sub BHN//DELTAV/sub M/) strongly depends on the applied stress but is independent of the distance between a sensor and a specimen. It is found from this result that the stress can be measured even under non-contact conditions by the BHN method applying the parameter. DELTAV/sub BHN//DELTAV/sub M/.
Sanford-Francis, C.H.A. Safe service life availability from measurements of magnetic material change in metals 39301
B r i t i s h J o u r n a l of N o n - D e s t r u c t i v e Testing, Vol. 30, No. 5, pp. 342364 (Sep. 1988) This paper outlines a magnetic inspection procedure which measures the rate of material change in metals electromagnetically, precisely locating regions of fatigue damage early in the fatigue process, long before cracks develop in metal. Results show that changes in magnetic permeability can be used to predict failures in service so components can be withdrawn from service before breakdown. The procedure has proved simple and safe. 39146 Brudar, B. M a g n e t i c leakage fields calculated by the met.hod of finite differences P r o c e e d i n g s of the 4 t h E u r o p e a n C o n f e r e n c e o n N o n - D e s t r u c t i v e
54
Testing, L o n d o n ( U n i t e d K i n g d o m ) , 13-17 Sop. 1987. Vol. I. pp. 665-674. P e r g a m o n Press, 3173 pp. (1988) Magnetic leakage fields around a surface crack in a ferromagnetic matcriat have been measured and calculated on basis of simplified assumptions. In this article the detailed description of the necessary suppositions at specified mesh points in the numerical procedure (FD) is given, taking into account the dependence of the relative permeability on the magnetic field strength. 39145 Jiles, D.C. Review of magnetic methods for nondestructive evaluation N D T I n t e r n a t i o n a l , Vol. 21, No. 5, pp. 311-319 (Oct. 1988) This paper provides a guideline to the literature of magnetic techniques to~ nondestructive evaluation. Compared with other NDE methods such as ultrasonics or eddy currents, the literature for magnetic methods is relatively small, but one of the difficulties is that it is widely scattered. This review therefore presents a fairly comprehensive summary of works on Barkhauscn effect, magnetoacoustic emission, magnetic hysteresis, residual field and magnetically induced velocity change methods that have appeared to data 39144 Wang Yangsheng; Shi ttanmin; Yan~ Shuzi. Quantitative wire rope inspection N D T I n t e r n a t i o n a l , Vol. 21, No. 5, pp. 337-340 (Oct. 1988) This paper describes a complete system for inspecting wire ropes automatically. Obstacles to the development of such a system are analysed m detail, followed by a description of the hardware and software of the system The hardware uses 12 Hall effect sensors arranged in a circle around the wire rope. Signal analysis is based on a pattern recognifionapproach. Selection of the feature vector and the use of a trainable non-linear classifier arc described 39143 Anotl. Introduction to flaw detection during production by magnetoelastie testing using Barkhausen noise (In French) Q u a l i t e R e v u e P r a t i q u e de C o n t r o l e I n d u s t r i c l , No. 150, pp. 104-! I~! ( A p r . 1988) 39142 Kaplan, B.Z,; Rabinovici, R. Nondestructive evaluation of ferromagnetic 'magnetometer like' experimental arrangement
materials
by
a
J o u r n a l of N o n d e s t r u c t i v e E v a l u a t i o n . Vol. 6,, N o 2, pp. 73-80 (,hm. 1987 ) The paper presents experimental results regarding tbc influence ol mechanical stresses and thermal treatments on the Barkhausen noise anti magnetization characteristic of MolyPermanoy and MuMetal ferromagnetic samples. The samples are different in stress magnitude and localization and in their thermal history. The level of Barkhausen noise and the changes itl magnetization characteristic arc estimated by measuring the sensitivity and transduction gain of 'magnetometer like' coils configuratkms which employ the studied ferromagnetic samples as their nonlin~car ferromagnetic cores: The present method is unique in the sense that the two factors (one factor is related t~ the internal magnetic noise, and the other one is related to the form of the magnetic characteristic) arc obtained by employing a single relatively simple experimental arrangement. Various types of stresses, which arc different in magnitude and localization, become distinguishable one from the other, when considering their differential effects on the two factors. Se~vra/ possible experimental arrangements are shown. 39141 Ponomarev, Yu.F. Harmonic analysis of the magnetization of ferromagnets remagnetized by an AC field, with magnetic hysteresis taken into account. IV. Application to nondestructive inspection Soviet J o u r n a l of N o n d e s t r u c t i v e T e s t i n g , Vol. 23, No. 6, pp. 430-439 (Feb. 1988) The article analyzes the possibilities of using one harmonic of the secondary electromagnetic force (emf) for determining three magnetic characteristics of the inspected objects when families of special symmetric magnetic hysteresis
NDT International February 1989