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Vibrations globales - corps entier (RSS)
Operators of load-haul-dump (LHD) vehicles are commonly exposed to wholebody- vibration (WBV) levels above ISO 2631-1 and EU Directive 2002/44/EC guidelines. Vibration exposure was lowest when the LHD was driven at the lowest speed, forward, over smooth terrain, with ride control on and the bucket loaded (0.20 m/s 2 ). The A(8) decreased from 0.84 m/s 2 when driving with ride control off, over mixed terrain using all gears, to 0.53 m/s 2 when driving with ride control on and an optimized seat. The estimated daily exposure decreased but remained just above the ISO 2631-1 and EU Directive 2002/44...
For motions with high crest factors, the vibration discomfort of standing people tends to be underestimated by rms methods (with an exponent of 2) and overestimated by rmq methods (with an exponent of 4). The optimum evaluation method in this study with standing people exposed to fore-and-aft, lateral and vertical vibration had an exponent of about 3.0 for transient motions centred on 1 Hz and an exponent of about 3.5 for motions centred on 8 Hz. The findings of this study with standing people are broadly consistent with studies using different motions and different psychophysical methods with...
Typically drivers of container-bridge cranes are forced to sit with a forward bent upper trunk to control the position and motion of the container. Fork-lift truck drivers incline the upper trunk to the side to look forward or they twist to one side during reversing. The forces transmitted in the lumbar spine were assessed by means of a biomechanical model. Under realistic vibration stress the bent postures result in an increase of the compressive and the shear forces. The increase of the spine forces is the result of the increased muscle forces stabilizing the inclined trunk. On container bridge...
This article explain that vibration injury is typical of the «slow accidents» that build through continued exposure to the so-called physical agents, which also include noise and radiation... damages many lives. It presents the syllabus of the NEBOSH National Diploma «Physical agents» and resumes information on Whole-body vibration and Hand-arm vibration. In his series for NEBOSH National Diploma students, Lawrence Bamber details the risks posed by vibration, its effects on the individual and assessment and control of exposure. Source : Bad Vibes . Bamber, L. Health and...
Objectives The aim of this study was to investigate whether whole-body vibration (WBV) is associated with prolapsed lumbar intervertebral disc (PID) and nerve root entrapment among patients with low-back pain (LBP) undergoing magnetic resonance imaging (MRI). Methods A consecutive series of patients referred for lumbar MRI because of LBP were compared with controls X-rayed for other reasons. Subjects were questioned about occupational activities loading the spine, psychosocial factors, driving, personal characteristics, mental health, and certain beliefs about LBP. Exposure to WBV was assessed...
Dans le cadre des travaux du Réseau prévention sur la limitation des vibrations au poste de travail, l’INRS a mené une étude portant sur les transpalettes électriques à conducteur porté. Une problématique que certaines entreprises prennent également en compte lors de l’acquisition de transpalettes. Le niveau de vibrations subies par le cariste dépend d’abord de l’engin qu’il conduit, mais également de l’état des sols, de sa posture, de sa façon de conduire. Source : Travail...
This study investigated the effects of reclined backrest angles on cognitive and psycho-motor tasks during exposure to vertical whole-body vibration. Apart from 22.5° seat backrest angle for the tracking task, backrest angle did not adversely affect the performance during vibration. However, participants required increased effort to maintain performance during vibration relative to the stationary condition. These results suggest that undertaking tasks in an environment with vibration could increase workload and risk earlier onset of fatigue. Source: The influence of seat backrest angle on human...
A single degree-of-freedom simulation model of a seat equipped with a non-linear fore-and-aft suspension system was developed. The performance of a typical fore-and-aft suspension system was analysed using typical vibration and shock acceleration signals measured in loaders while travelling on off-road terrain and while driving the bucket into a heap of soil. The simulations are of use to seat manufacturers in developing improved fore-and-aft seat suspension for wheel loaders. Source: Study of simultaneous shock and vibration control by a fore-and-aft suspension system of a driver’s seat...
Vibratory soil compactors are articulated vehicles designed to achieve efficient compaction of the soil and road base-layers through a vibratory drum/roller integrating an unbalanced rotating mass. The low frequency whole-body vibration are directly transmitted to the operator through the driver seat, which in the vast majority of the vehicles employed in Québec is limited to a polyurethane foam cushion. The results of this study suggest that the seat and the cabin mounts amplify the low frequency vibration for all the vehicles considered but this amplification is limited for the 13-ton...
A predictive discomfort measure considering the combined neck and trunk is introduced in this work and compared with the seat-to-head transmissibility and subjective reported discomfort due to fore-aft whole-body vibration of seated subjects under two sitting postures. The proposed discomfort quantifies whole-body musculoskeletal discomfort considering body posture, closeness of the joints to their limits, and severity of the angular acceleration at the joints. The proposed predictive discomfort captured the trend of the subjective reported discomfort and showed good potential to capture the effect...
In the largest case-control study of Parkinson's disease conducted in Canada to date, Parkinson’s disease showed u-shaped pattern of risk for whole body vibration : increased risk among those with no exposure, and among those with exposure, increasing risk with increasing intensity of exposure. Among those with exposure, there were increasing odds of Parkinson’s disease with increasing intensity of exposure and with increasing censoring of exposure in the years prior to diagnosis. The odds ratio was statistically significant in the second highest intensity category, for exposures...
The health effects of vibration exposure in drummers can result from extended periods of contact between a drummer and the vibrating surface they are exposed too. Drummers particularly are at risk since they can be exposed to vibration through multiple body parts such as the hands-stick-drum head, feet-pedals-base drum head and or hi hat or from the buttocks-seat-floor interfaces. Drummers can develop symptoms including back pain, diminished sensation and dexterity in the hands or feet, decreased grip strength, vascular injury resulting in finger blanching or “white fingers”, tendonitis...
The risk of falls from height on a construction site increases under conditions which degrade workers' postural control. At elevation, workers depend heavily on sensory information from their feet to maintain balance. The study tested two hypotheses: undetectable random mechanical vibrations at the plantar surface of the feet can improve worker's balance at elevation; and detectable random mechanical vibrations can have a degrading effect on balance in the same experimental settings. Sensory suppression (detectable vibration) associated with elevated vibration levels on a construction site...
Although it is not possible to conclude that high levels of WBV exposure were the only cause of the reported neck and back discomfort, vibration levels experienced by the underground mining load-haul-dump ( LHD) operators indicated health risks were likely to develop, with a higher probability of injury to the back. Analysis of all operators’ injury profiles and their vibration profiles will be important in future studies in order to determine whether these variables are related. The mining industry will need to consider a number of different intervention strategies to have an impact on injury...
European workers in transport over land and through pipelines seem also to be more exposed to vibrations from tools and machinery than the average working population. Several studies demonstrate the detrimental consequences of sustained sitting and being exposed to whole body vibration: exposure to vibrations may lead to back disorders. Based on the information available on heavy machines, the significance of the seat is important when steps to reduce full-body vibrations are taken. Full body vibration, for example caused by the driver’s cabin, may also affect the vision, coordination and...
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