Transmission of vibration in the hand-arm system with special reference to changes in compression force and acceleration.

Abstract

A handle with strain gauges attached ·was used to study the effect of compression force (10, 20 and 40 N) and constant acceleration (1, 3 and 10 g) on the transmission of vibration at frequencies from 20 to 630 Hz. In the curves recorded, sharp dips appeared which were evidently caused by resonances from the soft tissues of the hand. However in the hand-arm system no common resonance frequency was observed that would harmfully affect the health of workers. Vibration in the hand-arm system was attenuated at an average of 3 dB per octave at the frequencies between 20 and 100 Hz. Between 100 and 630 Hz the attenuation was about 6 dB per octave in the wrist and 10 dB per octave in the elbow and upper arm. At the frequency of 630 Hz the attenuation was hence about 35 dB in the wrist and about 45 dB in the elbow. The attenuation of vibration in the elbow joint was 2 to 4 dB at all frequencies. The hand-arm system appears to be linear at the acceleration range considered; the increase)n handle vibration by, e.g., 10 dB also increased vibration in the hand by 10 dB. When the grip strength was increased fourfold, Le., 12 dB, vibration increased only 3 to 5 dB in the hand-arm system. Thus changing the weight of a vibrating tool does not reduce vibration enough. Therefore attempts to reduce Vibration should concentrate on the mechanical parts of the engines.

Impulse noise and hand-arm vibration in relation to sensory neural hearing loss.

“…Vibration measurements at the wrist showed that the hand-arm system operates as a low pass filter resembling the weighting presented in the international standard (38). Therefore, we cannot expect that hand-arm vibration would mechanically interfere with cochlear function .…”

Biodynamic Response at the Palm of the Human Hand Subjected to a Random Vibration

“…A larger hand may have more tissue in contact with the handle thus resulting in a higher response. At such frequencies, the vibration cannot be transmitted beyond the hand 25,26) , and the energy absorption is likely limited to the local hand tissues. The VPA values at the high frequencies are also relatively low.…”

“…Like an anti-vibration glove, the isolation effectiveness of the palm spring-damping system depends on vibration frequency. At low frequencies (<40 Hz), the palm cannot effectively isolate vibration, so the vibration can be effectively transmitted to the entire hand-arm system [25][26] , and a large percentage of the hand-arm system mass is involved in the low-frequency motion. Therefore, a larger hand-arm size can provide more mass to the response and result in a positive correlation between the anthropometrics and the magnitude of the biodynamic response.…”

“…Depending on the frequency characteristics, vibration generated from different tools can be transmitted to different parts of the hand-arm system 25,26) , and may cause various problems at these different locations 2,3,27) . It has been reported that the nature of the vibration power transmitted to the palm is much different from that into the fingers 28) and that the mechanical impedance distributed at the fingers is very different from that at the palm of the hand 29) .…”

Los guantes antivibratorios: ¿une avenida de prevención eficaz y aplicable?

“…El comportamiento biodinámico del sistema mano-brazo, sin guantes, está influenciado de manera considerable por las fuerzas de acoplamiento de la mano (Pyykkö, Färkkilä, Toivanen, Korhonen & Hyvärinen, 1976;Griffin, Macfarlane & Norman, 1982;Aatola, 1989;Gurram, Rakheja & Gouw, 1994/1995 y, en menor medida, por la amplitud de la aceleración (Reynolds & Keith, 1977;Gurram, Rakheja & Gouw, 1994/1995Besa, Valero, Sufier & Carballeira, 2007). De esta manera, es probable que estos factores influencien la transmisibilidad o la atenuación de los guantes (Griffin, 1990;Dong et al, 2004).…”