50791 Basso. M.N , St Lawrence. S Detect ion of smal l fat igue c r acks at inc lus ions in rail steels wtth

acoust ic emission Non-Destructive Testmg 92_ Proceedmgs of the 13th World Conference on Non-Destructive Testing, Sao Paulo (Brazil), 18-23 Oct 1992. Vol 1, pp 66-70_ Edited by C Hallat and P Kulcsar.

Elsevier (1992) Recently, one of the authors (MNB) has developed and patented a tiered

approach for using acousuc emission for continuous, automated stand alone momtonng of structures and components (This resulted m the commercial Monac Technology) In the present study, this approach was used, in a predictive way, to investigate the effect of inclusmns on the onset of crack growth in raul steels. Speofic signal parameters from real fatigue signals were preprogrammed In the acoustic emission system The experimental procedure revolved high cycle fatigue of 4- point bending specimens while acoustic emission was monitored using a Monte expert system equlpmenL The testing was stopped whenever the first indication of activity, manifested by a measurable (delta K), would occur_ This was followed by optical and scanning electron microscopy to detect the source of cracking at the inclusions The results show clearly that acoustic emission detects the onset of crack growth. Cracks emanating from inclusions, as small as 0_009 mm m length were observed The success rate of detection was 100%_ Thus it was possible, with this technique, to perform a quantitative study of fatigue of rad steels m real ume

50755 Burkhardt. G_L_ Deve lopmen t of a da ta m a n a g e m e n t sys tem and B a r k h a u s e n noise analysis res idual s t ress m e a s u r e m e n t c r i te r ia for freight car wheels Southwest Research lns t , San Antomo, Texas (Umted States), PB92- 143023/GAR, 86 pp_ (Nov 1991)

Southwest Research Insmute (SWRI) began development of the Barkhausen noise analysis (BNA) method for measunng residual stress in railroad wheels for Burhngton Northern m 1982 At that time, a government rule required that wheels be removed from service if they had 4 or more inches of discoloration extending from the nm into the plate region on either side of the wheel This requirement resulted in Burlington Northern discarding approximately 20 percent of the railroad wheels processed by its Havelock wheel shop. even though considerable evidence showed that large numbers of the wheels rejected according to the rule were actually good The objective of the BNA work was to develop a method for discarding wheels based on actual thermal damage, with the goal of reducing both the number of discarded wheels and associated cost to Burhngton Northern

50467 Wester. P_I , Wang. X , Mdls. G P r o b l e m s with ra i lway rails

Measurement of Residual and Apphed Stress Using Neutron Dfffracuon Edited by M T Hutchmgs and A D. Krawitz. pp. 517-524 Kluwer Academic Pubhshers (I 992)

Neutron diffraction is now being apphed to measure macroslrmn distributions mslde components of engJneenng interest Tbe technique has several umque advantages but there are practical constrmnts which hmit its widespread adoption Compromises are often necessary to bridge the gap between what is required by engineers for use in stress analysts calculations and what ~t is practical to measure using the techmque, especially when large sized components are involved An example rs given of how neutron stra,n scanning may be applied, m a hm=ted but cost effective manner, to the problem of the "non- destructive" measurement of residual stresses in complex shaped large components such as railway rails

50264 Saka, M. Yuasa. D. Abe, H , Sugmo, K Nondes t ruc t ive cha rac t e r i za t ion of b i fu rca ted crack by potent ial d r o p technique Nondestructive Testing Evaluation, Vol 7, No I-6, pp. 61-72 (1992)

A method was presented for the nondestructwe evaluauon of a crack bifurcated from a horizontal crack m a ra,I The method was based on the measurement of the difference and dlsmbutmn of d c. elecmcal potenual on the top surface of the rad First. a problem of current flow m a plate, which contained horizontal and bifurcated cracks and was subjected to a uniform current was analyzed numerically by using a 2-D finite element method The potent=at distribution on the measunng surface of the plate was obtained for vazaous combinations of the cracks The potential d=stnbutton showed a remarkable change m its slope just above both ends of the horizontal crack Also the relation between the vertical component of the bifurcated crack and the total potential difference above the horizontal crack was revealed to be independent of the combinations of the cracks Next, in order to characterize the cracks m actual rail based on the 2-D numencal analys~-, a method was introduced for obtaanlng a rectangular secuon electrically equivalent to the

ND T Abstracts

section of actual rad Finally. tt was verified by experiments using rail specimens that the cracks were charactcnzod quantitatively through the present numerical results together with the use of the eqmvalent section

50176 Schramm, R E, Shull, P J , Clark, A V, Mttrakovt~, D V C r a c k inspect ion of ra i l road wheel t r eads by E M A T s Nondestructive Characterization of Materials, 3rd International Sympos ium, Saarbrucken (Germany), 3-6 Oct. 1988. pp. 421-428 Edited by P. Holler, V Hauk, G Dobmann, C_O. Ruud, and R E

Green Spnnger-Ver lag (1989) For some years, ultrasonic testing has been apphed to the detection of

cracks in wheel treads, with parucular attenuon to automatic, m- rail, roll-by methods. We have begun constructing a system a,med at using relatively low frequency Rayleigh waves generated by electromagneuc-acousttc transducers (EMATs) The current design uses a permanent magnet to maintain a compact structure and minimize the size of the pockel machined into the ra,I Measurements thus far indicate a responsiveness, even to small flaws With the development of a signal processing and analys~s system. field tests should soon be possible

50048 Gong, Z., Nyborg, E 0 , Oornmen, G Acoust ic emiss ion m o n i t o r i n g of steel r a i l road b r idges Materials Evaluation, Vol 50, No_ 7, pp. 883-887 (Jul 1992)

Results from acoustic emission (AE) momlonng of 36 steel railroad budges are presented. "l'he demonstrated successes of using AE to find new cracks, to identify active cracks, to vahdate the effectweness of repazrs, and to provide damage assessments to assist with repazr pnonzarlon are discussed The challenges presented in using AE for fatigue-life estimation, for the assessment of pins. hangers and complex weldments, and for crack assessment of severely corroded members are outlined Finally, new ideas for refined momtonng and enhanced data analysis aura presented

49885 Lebedev, A.A Acoust ic h a r d n e s s tests of ra i l road rails Soviet Journal of Nondestructive Testmg, Vol_ 27, No 10, pp.

713-717(Jun 1992) We invesugated the correlation between hardness and speed of

propagation of acoustic surface waves in raal steel_ The article presents the results of hardness tests of raulroad ra,ls with an acoustic hardness tester based on the method of autoclrculauon of pulses

49737 Izbmsky, G Feasibi l i ty s tudy of utilizing a synchron ized laser s c a n n e r for rail inspect ion Transportation Development Center, Montreal, Quebec (Canada), MIC-91-03669/GAR, 131 pp (1990)

Non-contact measurement devices am preferred by radways and track maantenance contractors for safety-related inspections of rail because they do not require repa,r and replacement as frequently as their mechanical (contact) counterparts Tlus report presents the results of an evaluation of a synchromzed laser scanner m field tests on CP Rail tracks in Montreal and Smiths Falls. The test car, eqmpped with the scanner, passed over the same zones at different speeds collecting data wLuch represented the distance from the car body to the rail surface sampled at I 5 inch intervals The raw data was then processed using specially written software, and compared to the result of the reference measuremenL

49716 Hartharan, S Deve lopmen t of i n s t r u m e n t a t i o n for magne t i c n o n d e s t r u c t i v e eva lua t ion Ames L a b , Iowa (Umted States), DE 92000152/GAR. 128 pp. (Sep. 1991)

This thesis describes the modifications made to existing instrumentation used for magneuc measurements at the Center for Nondestructive Evaluation at Iowa State Umversity Development of a new portable instrument is also given An overview of the structure and operation of this Instrumentauon is presemed This thesis discusses the apphcatron of the magnetic hysteresis and Barkhausen measurement techniques, described in Secuons 1_31 and 13 2 respecuvely, to a number of ferromagnetic specimens Specifically. measurements were made on a number of railroad steel specimens for fatigue characterization, and on specimens of Damascus steel and Terfenol-D for materials evaluation_

49691 Kopec, B Eva lua t ion of s t r u c t u r a l fac tors v a c u u m mel ted steel by ul t rason ic a t t enua t ion technique in the r a i lway axles Ultrasonics Internat,onal 91, Le Touquet (France), 1-4 Jul. 1991 pp. 547-550. Butterworth Hememann (1991)

The present work is a characterization of the structures of radway axles

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