Vibration - 974 entries found
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Holmer C.I., Lagace A.
Effect of structural damping on the sound radiated from impacted structures
In the first part of this paper, a mathematical model is developed to permit the estimation of the reduction in impact noise due to the addition of mass, stiffness and damping to an impacted system. The change in peak radiated sound pressure level from an impact is found to be proportional to the change in mass and stiffness of the impacted surface. The second part of the paper presents the results of experiments carried out on a foundry hopper before and after damping; there was substantial agreement between the calculated and measured energy noise reductions.
American Industrial Hygiene Association Journal, Jan. 1972, Vol.33, No.1, p.12-18. Illus. 1 ref.
Vascular disease disorders resulting from vibrating tools
A general review of the aetiology, development, diagnosis and prevention of disorders due to vibrations transmitted to the hand-arm system.
Journal of Occupational Medicine, Feb. 1972, Vol.14, No.2, p.129-133. Illus. 6 ref.
Vibration induced peripheral syncope
La syncope périphérique par vibrations [in French]
Examination of 11 cases of vibration-induced peripheral syncope (Raynaud's phenomenon, "dead finger") amongst 222 vibration-exposed metalworkers in 2 large machine-tool plants instigated clinical studies (classification, aetiology, symptoms, course) and biophysical and physio-pathological studies. Discussion of the results in relation to the extensive literature lead to conclusions relating to the perturbation of arteriolocapillary vasomotor function - the fundamental physiopathological disorder in vibration-induced peripheral syncope. An original hypothesis is proposed to explain the physiopathology of vibration-induced peripheral syncope.
Archives des maladies professionnelles, Jan.-Feb. 1972, Vol.33, No.1-2, p.31-44. Illus. 84 ref.
Ragu M., Roure L., Tisserand M.
Vibration in construction machines
Les vibrations des engins de chantier [in French]
Following a brief survey of the three ranges of vibration frequency and the disorders they produce, the authors review the research carried out at the INRS Nancy Research Centre on the reduction of construction-machine vibration-transmission to the driver: direct vibration measurements on various machines; studies on vibration-damping devices. Tests were made on 2 low-pressure-tyre wheeled loaders moving over construction sites at different speeds, loading earth and stones, levelling and crossing obstacles. Descriptions are given of the measuring instruments, the results and their evaluation.
Travail et sécurité, Mar. 1972, No.3, p.149-157. Illus.
Jackson C.E.P., Grimster W.F.
Human aspects of vibration and noise in helicopters
A survey of the types and sources of helicopter vibration. Methods of vibration testing and monitoring are dealt with and the relative merits of various methods of vibration reduction are reviewed. Acceptable in-service levels of vibration are described in terms of vibration velocity limit and the International Organization for Standardization/British Standards Institution proposals concerning "fatigue-decreased proficiency". Internal and external noise are briefly discussed and some information is given on results of internal cabin-noise reduction.
Journal of Sound and Vibration, 8 Feb. 1972, Vol.20, No.3, p.343-351. Illus. 3 ref.
Selection of electric-truck suspension characteristics on the basis of model studies
Możliwości doboru właściwych charakterystyk zawieszenia elektrowózka na podstawie badań przeprowadzanych na modelu [in Polish]
Description and diagrams of a test bench designed by the Polish Central Institute for Workers' Protection (CIOP) for experimentally determining electric-truck suspension characteristics. It comprises a model of an industrial electric truck, a vibration generator, and electric motor, hinged parallelograms and stabilisers. The design principles of the shock absorbers studied are described together with the method used and the measurements carried out. This test bench can also be used for studying vibration in other types of in-plant transport equipment.
Prace Centralnego instytutu ochrony pracy, 1972, Vol.22, No.73, p.105-126. Illus. 14 bibl.
Noise problems in electric motors and equipment
Geräuschprobleme bei Motoren und Geräten [in German]
Vibration problems with their numerous, irregular phenomena can be described and studied only by probability forecasting. Electronic data processing is of value in optimising the noise level in the development of motors and equipment. The author describes test results obtained with various rotors and explains inter alia the effects of incorrect balancing. The use of statistical procedures and electronic data processing in quality control is described.
Elektrotechnische Zeitschrift, 9 June 1972, Vol.24, No.12, p.287-289. Illus. 5 ref.
Henkel W., Krause P., Rothe R.
Industrial hygiene measurement and evaluation of whole-body vibration
Arbeitshygienische Messung und Bewertung von Ganzkörperschwingungen [in German]
After a review of current knowledge on the effects of whole-body vibration and of proposals for the evaluation of these effects, the thresholds laid down in TGL 22 312 are discussed. This standard is based on an ISO proposed guide for the evaluation of human exposure to whole-body vibration (ISO/TC 108/WG F, Dec. 1968). The thresholds apply to mechanical vibration in the 1-90Hz frequency range and are specified in terms of vibration frequency, acceleration level, exposure time and the direction of vibration relative to the torso. The evaluation procedure is explained with the help of examples, and the measurement methodology is studied.
Zeitschrift für die gesamte Hygiene und ihre Grenzgebiete, Mar. 1972, Vol.18, No.3, p.161-165. Illus. 11 ref.
Further study of combined heat, noise and vibration stress
An earlier experiment (see CIS 72-1098), had failed to show any evidence of additive effects in the case of combined exposure to heat, noise and vibration stress. This result was confirmed in the present study, which also indicated that human performance was more impaired in vibration exposure alone than in combined exposure to all 3 stresses. An attempt is made to explain this apparently antagonistic stress interaction, which appears to be due to incrased motivation and application of effort by the subjects during the combined exposures rather than to any physiological effect.
Aerospace Medicine, June 1972, Vol.43, No.6, p.641-645. Illus. 4 ref.
Oeser R., Selig R.
The value of acral oscillography in functional circulation disorders in pneumatic-tool workers
Über die Aussagekraft der akralen Oszillographie bei funktionellen Durchblutungsstörungen durch Arbeit mit Pressluftwerkzeugen [in German]
Acral cardiovascular disorders due to medium- and high-frequency vibration produced by portable rotary and percussion tools are shown to be early symptoms of pneumatic-tool-induced lesions. Description of an oscillographic functional test for the diagnosis of vasospastic reactions in the peripheral vessels of the upper extremities, which showed significantly more pathological reactions in vibration-exposed workers than in non-exposed controls. The importance of this test for pre-employment medical examinations and expert medical opinions is emphasised.
Das deutsche Gesundheitswesen, May 1972, Vol.27, No.20, p.942-944. Illus. 15 ref.
Bannister P.A., Smith F.V.
Vibration-induced white fingers and manipulative dexterity
Report of a study to determine the extent of manipulative skill in persons suffering from "vibration-induced white fingers" (Raynaud's phenomenon) due to prolonged use of portable power saws. Comparison of the results of Purdue pegboard testing amongst power saw users and controls showed that vibrating tools may have discernible effects on fine manipulative skills, significant differences and consistent trends being found between the scores achieved by the 2 groups. The dominant hand, usually tensed in holding the trigger grip and absorbing the greater part of the vibration, tended to be the most affected. It is concluded that loss of fine manipulative skill should be included among the possible sequelae of prolonged use of hand-held vibrating tools.
British Journal of Industrial Medicine, July 1972, Vol.29, No.3, p.264-267. 12 ref.
Hellstrøm B., Andersen K.L.
Vibraton injuries in Norwegian forest workers
413 forest workers from 3 areas of eastern Norway, 296 of whom used chain saws, were examined. The prevalence of Raynaud's phenomenon was 47% in chain saw operators, 14% in forest workers not exposed to vibration, and 9% in 302 indoor workers not exposed to vibration. The high prevalence of Raynaud's phenomenon in chain saw operators was attributed to a traumatic vasospastic disease. The average latent period was 8 years. The standard symptoms of traumatic vasospastic disease were attacks of blanching and numbness. Cyanosis and pain occurred rarely. In subsamples, measurements of tactile 2-point discrimination and maximal isometric muscle strength (hand grip and finger pressure) as well as X-ray examinations of the wrists and hands gave no evidence of vibration injury to peripheral nerves, muscles, bones or joints.
British Journal of Industrial Medicine, July 1972, Vol.29, No.3, p.255-263. Illus. 68 ref.
Noise and vibration control
Largely based on material developed for special noise and vibration control courses, this book is intended for engineers who have no special training in acoustics. It assembles a wealth of practical and detailed advice on the fundamentals of sound, the mesurement and analysis of noise and vibration and the available methods of control. The volume is profusely illustrated and contains many solved problems. It is supplemented by useful data on units and conversion factors and an extensive table enabling conversions to be made between decibels and power and soud-pressure ratios and vice versa. There is a detailed alphabetical index.
McGraw-Hill Book Company, 330 West 42nd Street, New York, NY 10036, USA, 1971. 650p. Illus. 426 ref.
Anitesco C., Contulesco A.
Studies on the influence of noise and vibration on the behaviour of catecholamines in an environment of industrial noise and vibration
Etude de l'influence du bruit et des vibrations sur le comportement des catécholamines dans l'agression sonore vibratoire industrielle [in French]
In order to study the effect of noise and vibration on the medullo-adrenal and sympathetic systems, the authors examined 80 mechanical engineering workers exposed to noise and vibration and 20 controls; they determined vanillic-mandelic acid (VMA), 17-ketosteroids (17-KS) and creatinine in urine. After 4h of work, exposed workers were found to have a 28% increase in VMA and a 14% reduction in 17-KS. Following 8h of night rest, there was a 15% fall in VMA in comparison with the controls; there was a similar reduction in 17-KS. This shows that, in exposed subjects, recuperation of cell-energy potential does not follow immediately upon the cessation of noise and vibration exposure, due to inadequate endocrine irrigation. Consequently it is necessary to arrange work breaks accordingly and to ensure suitable rest after work.
Archives des maladies professionnelles, July-Aug. 1972, Vol.33, No.7-8. p.356-371. Illus. 12 ref.
Peripheral neuropathy in forest workers - A field study
Account of a study carried out in 6 Finnish lumber camps where bilateral measurements were made on 103 lumbermen to determine the maximum motor conduction velocities (MCV) of the median and ulnar nerves and also the conduction velocity of the slower fibres (CVSF) of the ulnar nerves. The MCVs were delayed in 50% of the men observed. The CVSF was reduced in 40% of them. Tfindings show that the peripheral nerves in both the distal branches and the forearms were impaired, probably due to partial demyelinisation. The use of chain saws during 5 to 6h daily increased the symptoms of Raynaud's phenomenon with pain and paraesthesias in the arms.
Work - Environment - Health, 1972, Vol.9, No.3, p.106-111. Illus. 22 ref.
Emerson P.D., Overman H.S.
Reduction of noise from rotating textile spindles
Textile spindles are said to be responsible for about 80% of the total noise generated in spinning and twisting operations. Noise levels in textile yarn spinning generally exceed 90dBA; most of this noise is due to vibrations caused by unbalanced loads concentrated outside of bearing supports and is transmitted to machine frames and radiated to the air. Experiments were carried out by adding weight to pindle bolsters; this resulted in substantial vibration reduction, but in no corresponding noise reduction at a distance of 60cm from the spindle.
American Industrial Hygiene Association Journal, Apr. 1972, Vol.33, No.4, p.252-257. Illus.
Noise and vibration control in the rubber industry
Combaterea zgomotului şi a vibraţiilor în industria cauciucului [in Romanian]
The author analyses the main noise sources in the rubber industry and proposes several engineering solutions for suppressing noise sources or for preventing the noise produced from exerting harmful effects on the body. With the help of photographs and diagrams, he describes a number of noise-control devices for compressor stations, pumps, starters, burners, pressure reducers, fans, pneumatic tools, etc. A number of the solutions proposed are novel and could be utilised in other branches of industry.
Industria uşoară, Aug. 1972, Vol.19, No.8, p.498-502. Illus. 3 ref.
Wasserman D.E., Badger D.W.
The NIOSH plan for developing industrial vibration exposure criteria
A brief outline of the programme developed by the National Institute for Occupational Safety and Health (NIOSH) for establishing standards of occupational exposure to vibrations, preceded by a summary account of the extensive literature search carried out in this connection; this account is presented on a country basis.
Journal of Safety Research, Dec. 1972, Vol.4, No.4, p.146-154. 103 ref.
Okada A., Yamashita T., Ideda T.
Screening test for Raynaud's phenomenon of occupational origin
Experiments were conducted on 13 chain-saw operators in whom the presence of Raynaud's phenomenon had been confirmed, and on a control group performing the same work. The efficiency of various screening test methods for diagnosing Raynaud's phenomenon between attacks was examined (skin temperature, palm press test, nail press test, grasping power, reactive congestion test, rheumatoid arthritis test, and cold pressor test), and an attempt was made to discover a new method. The results obtained are tabulated and discussed. The cold pressor revovery index of diastolic blood pressure appears to be very useful in the early detection of Raynaud's phenomenon when the subject is seen between attacks.
American Industrial Hygiene Association Journal, July 1972, Vol.33, No.7, p.476-482. 14 ref.
Dupuis H., Broicher H.A.
Measurement techniques for determining the stress imposed on man by vibrations
Techniques de mesure des vibrations auxquelles l'homme est exposé. [in French]
French translation of: Messtechnishe Verfahren zur Bestimmung der Schwingbelastung des Menschen. Messtechnische Briefe, Darmstadt, Germany (Fed.Rep.), Apr. 1969, No.1, p.12-15. Illus. 13 ref. The authors first consider the basic parameters which must be understood in order to evaluate vibrations and then discuss the method of measuring vibration acceleration, and the mode and force of vibration. In discussing amplitude classifications as a method of evaluation, they present in a diagram the results of 438 driving tests on motor cars, earthmoving machines and tractors. A vibration range of 0.5-5m/s2 was recorded at the driver's seat. Frequency analysis is also briefly discussed.
Translation INRS 113 B-71, Institut national de recherche et de sécurité, 30 rue Olivier-Noyer, 75680 Paris Cedex 14, France, 1971, 14p. Illus. 13 ref.
Sevin E., Pilkey W.D.
Optimum shock and vibration isolation.
This monograph deals with the best methods available in the engineering design of shock and vibration isolation and consists of 8 chapters devoted to: optimisation criteria; shock and vibration environments; optimum isolator design formulation; limiting performance characteristics of shock isolation systems; optimum design synthesis of shock isolation systems; harmonic vibration isolation systems; random vibration isolation systems. The volume contains 10 examples with the corresponding mathematical calculations and is supplemented by an annotated bibliography and an index.
The Shock and Vibration Information Center, Naval Research Laboratory, U.S. Department of Defense, Washington, D.C. 20390, USA, 1971. 162p. Illus. 151 ref.
Jandová D., Krofta V., Titman O.
Electromyographic examination of ulnar nerve lesions in vibration-exposed workers
Elektromyografická studie poškození ulnárního nervu u pracujících v riziku vibrací [in Czech]
Mathematical comparison of the results of electromyographic examination (orthodromic and antidromic stimulation of ulnar nerve motor and sensory fibres) of 40 vibration-exposed workers and 40 controls showed wrist-finger conduction velocity (5-cm standard distance) to be lower in exposed workers. This is in agreement with clinical findings. Sensitivity defects, regularly found in clinical examination, are often followed by motor disorders. The antidromic stimulation technique is considered very sensitive for studying the course of vibration-induced ulnar nerve lesions.
Československá neurologie, 1971, Vol.34, No.2, p.64-68. Illus. 10 ref.
Letavet A.A., Drogičina Ė.A.
Vibrations in industry - Physics, occupational health and physiology, clinical aspects, physiopathology and prevention
Vibracija na proizvodstve - Voprosy fiziki, gigieny i fiziologii truda, kliniki, patofiziologii i profilaktiki [in Russian]
Monographs by several contributors on the following subjects: vibrations and their mechanical effects on man; problems of industrial hygiene and physiology associated with the use of vibrating tools (assessment of exposure to vibrations in certain occupations, physiological functions in workers using vibrating tools, study of effects of local vibrations on man, etc.); clinical picture of vibration sickness (general; details of clinical characteristics connected with various vibration parameters; clinical and physiological characteristics of the locomotor and circulatory systems; treatment); technical prevention and prophylaxis of vibration disease.
Izdatel'stvo "Medicina", Petroverigskij per.6/8, Moskva, URSS, 1971. 243p. Illus. 157 ref.
Handbook of noise and vibration control
A reference book including much new material and voering: psycoacoustics; sound fields, sound propagation; noise measurement techniques and instruments; torsional vibration; legal aspects; noise and vibration control; silencers; acoustic absorption materials, insulation, partitions, enclosures, windows, glazing; vibration generators; various types of buildings; different types of machinery (prime movers, road vehicles, electrical machines, pumps, pipework, heating and ventilation systems, pneumatic tools, etc.). Conversion and other useful tables. Buyers' guide (classified index). Trade name index. (For the first edition, see CIS 71-1733).
Trade and Technical Press Ltd., Crown House, Morden, Surrey, United Kingdom, 2nd ed., 1970. 609p. Illus.
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