On-line monitoring of wear

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  • 43181 Kido, K.; Abe, M.; Kanai, H. Detection of 1 micrometer order slight cracks on surface of bal l bearings by vibration analysis Proceed ings of the N a t i o n a l S y m p o s i u m on Acous t i c s , T i ruch i rapa l l i , ( Ind ia ) , 27-30 Dec . 1987. pp. 5-7 Acous t i ca l Socie ty of Ind ia

    A new automatic production-line technique for inspecting and classifying ball bearing is described. Flaws on the surfaces of balls and racers are detected using vibration analysis techniques. The ball bearings produced are classified according to the sizes and positions of flaws. Previously, human inspector tested to vibration signals through headphones. This unpleasant task has now been automated.

    43089 Bentsen, R.A.; Bush, A.J.; Harrison, J.A. Evaluation of nondestructive test equipment for airfield pavements. Phase 1, C a l i b r a t i o n tes t results and field data collection A r m y E n g i n e e r W a t e r w a y s E x p e r i m e n t a l S ta t ion , V icksburg , Miss iss ippi , ( U n i t e d S ta tes ) , A D - A 2 0 7 159 /5 /GAR, 331pp. (Jan. 1989)

    This study evaluates seven nondestructive testing devices for use on airfield pavcmcnts. Four falling weight deflectometers and three vibrators wcrc evaluated for accuracy, repeatability, and reliability. Deflection data wcrc collected on 12 pavements consisting of thick and thin asphalt concrete, portland cement concrete, and composite (asphalt concrete over portland cement concrctc) pavements over fine and coarse grain subgrades. This report dcscribes the test program, presents results of accuracy and repeatability tests, and presents the deflection data collected on the 12 pavemcnts.

    431)82 Pomerening, D.J. Analysis of vibration test data from Harpoon grade-B canister testing at Wyle laboratories Sou thwes t R e s e a r c h Ins t i tu t e , San A n t o n i o , Texas , ( U n i t e d Sta tes) , A D - A206 2 7 8 / 4 / G A R , 134pp (Mar . 1989)

    The purpose of testing was to perform nondestructive evaluation (NDE) of the HARPOON weapons system. In particular, the intent was to investigate the effect of modified shock isolation pads on the dynamic response of the missile/canister were compared. The testing was conducted with the production style isolation pads and a modified pad designed to reduce cost and installation complexity. The proposed isolation pads were prototypes, so the testing was exploratory in nature rather than aimed at qualification. To accomplish this task, four HARPOON Grade-B canisters on a Launch Support Structure (LSS. were subjected to a modified portion of vibration testing. HARPOON dynamic simulators were placed inside two of the canisters, while the other two were trainers. MIL-STDI67 vibration levels were chosen since the HARPOON system was designed to this requirement. During the testing the acceleration response at a number of points on the structure was monitored. The location of these points was chosen to provide information on the influence of the pads. as well as the general response of the entire structure.

    42930 Cherek, B.; Armannsson, J.H. High-frequency ultrasonic device for contactless measurement of mechanical vibrations Proceed ings of U l t r a son ic s I n t e r n a t i o n a l 89, M a d r i d (Spain) , 3-7 July 1989, 134-140, B u t t e r w o r t h Scient i f ic Ltd. ISBN 0408054182 (1989)

    A device based on the Doppler effect for contactlcss measurement of mechanical vibrations of plates, membranes, and wires is proposed. The contactlcss device consists of one high frequency ultrasonic transducer that acts as a transmitter and a receiver of the ultrasonic wave in a switching mode. Using one transducer instead of two, a bigger dynamic range is obtained in the vibration measurement. In comparison with the accclcromctcr the contactlcss device does not disturb the vibrations of even very light components as membranes, thin wires, etc. This device can also bc used for non-destructive flaw detection.

    42809 Boring, K.G. (ed) NDE Handbook, Non-destructive examination methods for condition monitoring B u t t e r w o r t h s , 418pp. (1989) ISBN 040804392X

    This handbook of nondestructive evaluation (NDE) produced in Denmark. describes the applications and limitations of NDE techniques to condition monitoring, as fixed by national and international standards. In condition monitoring, the choice of NDE method depends on material deterioration in a given environment, and often several methods arc combined. Various authors describe a wide range of NDE techniques which can bc used on their own or in combination to effect condition monitoring in the mechanical engineering and processing industry.

    428(/7 Hoddinott, D. Inspecting the Harwell reactors A t o m , No. 399, pp. 10-15 (Jan. 1990)

    This article outline the the protocol of safety inspections of the United Kingdom Atomic Energy Authority's reactors Dido and Pluto at Harwcll laboratory. The nuclear installations made a number of recommendations in its safety audit of these thirty years old reactors, which arc used as neutron sources. for neutron beam studies and for isotope production. The organisation and management of the inspection is described. Not only the reactors themselves, but also the surrounding concrete blocks and steelwork, were subject to a variety of nondestructive testing techniques. The tests were completed with satisfactory results within the timcscale alloted.

    42736 Mou, G.; Rishel, R.D. Measurement of intergranular attack in stainless steel using ultrasonic energy U.S. Pa ten t No. 4,854,173 (8 Aug . 1989)

    This device uses ultrasonic energy reflection from surfaces within the specimen to produce a measure of intergranular attack in stainless steel. An interface wave attenuation decibel ratio is determined from simple reflection measurements assuming no intergranular attack. Then the relationship between this ratio and the depth of attack is derived empirically. A second set of acoustic tests arc used to obtain a total reverberation echo decibel ratio from more than one surface. This ratio and the interface wave attenuation decibel ratio arc shown to be linked empirically and thence a first surface echo decibel ratio is derived.

    42573 Calchetti, G.; Cavaliere, G.; Federico. A.G.; Rufoloni, M. Vibration monitoring and diagnosis in large rotating hydraulic machines Proceed ings of the I n t e r n a t i o n a l C o n f e r e n c e on M o n i t o r i n g , Survei l - lance and Predic t ive M a i n t e n a n c e of P lan ts and S t ruc tures , T a o r m i n a - G i a r d i n i Naxos , Sicily ( I ta ly) , 15-18 Oct . 1989, pp. 729-737. I ta l ian Socie ty for N o n d e s t r u c t i v e Tes t ing

    The paper reports a diagnostic system project for a large centrifugal pump (about 6 MW). Vibration measurements results, made on bearings and pump casing, both in steady state and transient conditions, are shown. Furthermore acoustic emission measurements results, on seals and on pump casing, still in steady-slate and transient conditions, are shown. The collected data have been processed and analyscd with traditional algorithms (Fourier analysis, etc.) as well as with new techniques (Wigncr-Villc representation, Evolutionary Spectra, etc.). A similar experience is being developed to monitor and characterize a reversible pump turbine machine. In this case some additional problems have to bc solved, because of the greater complexity of the machine.

    42572 Cherek, B. Contactless vibration measurement based on the devices with one and two high frequency ultrasonic transducers Proceed ings of the In t e rna t i ona l C o n f e r e n c e on Mon i to r i ng , Survei l - lance and Predic t ive M a i n t e n a n c e of P lan ts and S t ruc tures , T a o r m i n a - G i a r d i n i Naxos , Sicily ( I ta ly) , 15-18 Oct . 1989, pp. 487-491. I ta l ian Socie ty for Nondes t ruc t i ve Tes t ing

    Two devices for the contactlcss vibration measurement arc presented. The operating frequency of these devices is very high and equal to about 1.8 MHz. Using the above instruments it is possible to measure velocity, displacement, acceleration and vibration distribution of even very light objects as loudspeaker membranes, thin wires, etc. The measurement range of the contactless devices is about the same as that presented by an accelcromctcr. The spectrum analysis of the output signals obtained by the presented devices shows the presence of flaws on the surface of the vibrating objects.

    42571 Amadasi, G. Automatic system for permanent vibration monitor and automatic fault detection/diagnosis Proceed ings of the In t e rna t i ona l C o n f e r e n c e on Mon i to r i ng , Survei l - lance and Predic t ive M a i n t e n a n c e of P lan t s and S t ruc tu res , T a o r m i n a - Gia rd in i Naxos , Sicily ( I ta ly) , 15-18 Oct . 1989, pp. 705-710. I ta l ian Society for Nondes t ruc t ive Tes t ing

    Machine maintenance is decided by the effective working conditions. The main problem to determine the effective conditions, that is the health state of the machine, could be solved by the measurement and analysis of vibrations produced by the machine. Today, it is also available on Automatic Monitoring System (Intelligent System) based on minicomputer endowed of a unique feature for faults diagnosis, with evaluation algorithms which may be taken from a library (data base) or keyed in directly from the operator.

    42567 Strelec. H. Quality control by spectral analysis In t e rna t iona l Jou rna l of Mate r i a l s and Produc t Techno logy , Vol. 3, No. 1, pp. 11-19 (1988)

    The construction of an inspection procedure for devices which arc working under mechanical stress is discussed. The underlying model assumes that vibration under a certain form of stress is nearly constant with a continuous spectrum. The observation of vibration at specified times leads to estimates of the spectral density functions. Two characteristic deviations between the estimated and the expected form of the spectral density function are discussed which arc the basis of a couple of quality control charts. On the one hand, some measure for a global difference between these functions (e.g. integrated squared differences) and, on the other hand, some measure for the greatest difference have to be used. For special measures concrete statistical inference is possible.

    42548 Rosen, J. On-line monitoring of wear Mechan ica l Eng inee r i ng , Vol. 111, No. 10, pp. 92-96 (Oct . 1989)

    By introducing on-line inspection into the design, operation and main- tcnancc of various mechanical systems, unscheduled downtime and production loss due to undetected wear and corrosion can be minimized, a number of nondestructive testing techniques can be used successfully here such as ultrasonic inspection, cddy current proximity transducers and surface layer actiwltion. Their method of use and some applications are described.

    NDT & E International April 1991 101


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