Vibration Dose Value Research Articles

SEMI-ACTIVE SUSPENSION INFLUENCE ON COMFORT SENSATION OF A VEHICLE OCCUPANT

This article presents an analysis of a modern-day vehicle semi-active suspension performance impact on comfort properties of its occupant. Vehicles chosen for the investigation had two different suspension-driving options, characterized as Comfort and Sport modes. These options change such vehicle parameters as suspension stiffness, algorithm of gearbox operation, and sensitivity of the steering system. Altering these two modes while driving at different speeds and on different road surfaces, vertical accelerations, affecting the occupant seat, were measured. Experiments and data processing were carried out according to ISO 2631-1 standard. After filtering the aforementioned vertical accelerations, the occupant comfort sensation was expressed as the vibration dose value (VDV) and the root mean square (RMS) of vibration acceleration value. Once the fast Fourier transform (FFT) was applied and vertical accelerations were converted to the frequency domain, spectral analysis of accumulated measurements was performed. After evaluating the comfort of an occupant, a summary of the vehicle suspension-driving mode influence is presented.

A cohort study of sciatic pain and measures of internal spinal load in professional drivers

In a prospective cohort study of 537 male professional drivers, the occurrence of sciatic pain showed stronger associations with measures of internal lumbar load expressed in terms of daily compressive dose, Sed (MPa), and risk factor, R (non-dimensional), according to ISO/WD 2631-5 (2013), than with measures of daily vibration exposure calculated as either 8-h energy-equivalent frequency-weighted acceleration (ms− 2 r.m.s.) or vibration dose value (ms− 1.75) according to the EU Directive on mechanical vibration (2002). Herniated lumbar disc, previous lumbar trauma and physical work load were also powerful predictors of the occurrence of sciatic pain over time. Psychosocial work environment was poorly associated with sciatic pain. The boundary values of risk factor (R) for low and high probabilities of adverse health effects on the lumbar spine, as proposed by international standard ISO/WD 2631-5 (2013), tend to underestimate the health risk in professional drivers.

Assessment of Passenger Ride Comfort during Vertical Vibration of Mid-size Saloon and Off-road Vehicles on Asphalt Roads

Ride comfort in road vehicles is related to vehicle vibration levels and the perception of passenger fatigue. In this study, vibration in vertical direction on the seat and floor are measured to characterise the ride comfort based on standard formulae and frequency analysis. A mid-size saloon vehicle and an off-road vehicle are driven on smooth, spalled and coarse asphalt road surfaces. To assess the vertical vibrations transmitted to the passengers, vibration dose values, Kurtosis, frequency response functions and power spectral densities of the compartment recorded signals were evaluated. Seat effective amplitude transmissibility value based on vibration RMS and vibration dose values were also evaluated. The results indicate that the vibration dose value increases in proportional to the vehicle speed and road roughness.

Office floor vibrations: evaluation and assessment

Excessive levels of vibration in office floors have become a common source of complaint by occupants and building owners in recent years. The need for large open-space working areas, the availability of light and high-strength building materials, the use of computer-aided design and lighter building contents due to paperless offices are the main factors causing the problem. The evaluation and assessment of floor vibrations as related to human perception and comfort are therefore important issues to consider. Several standards and design guides include provisions to address these requirements. The most recent research studies and standards recommend the use of vibration dose value (VDV) for such evaluation, which is believed to provide a consistent and reliable measure of vibration acceptability to humans. Using the results of tests conducted on four different building floors, this paper studies the provisions of the recent standards for the estimated vibration dose value (eVDV) and attempts to clarify their applications. It is found that a vibration duration based on a peak absolute frequency-weighted acceleration of more than 0·015 m/s2 provides consistent evaluations in terms of human reaction to vibration. This paper also compares the provisions of various standards and design guides in terms of building floor vibration acceptability levels. It is concluded that the use of VDV results in a more consistent and less conservative outcome than other criteria such as peak absolute acceleration.

An objective method of driveability evaluation using a simulation model for hybrid electric vehicles

Conventionally, driveability evaluations in vehicles are subjectively assessed by professional test drivers in automotive companies. To solve limitation of repeatability and time-consuming, this paper proposes an objective method of evaluating driveability during acceleration and overtaking conditions in a hybrid electric vehicle. Selected criteria are the acceleration value obtained by the root mean square (RMS), the vibration dose value (VDV), the response delay, and the peak-to-peak value of the acceleration and jerk. For human vibration, measured acceleration signals are applied to frequency weighting functions on the basis of ISO 2631-1. An objective evaluation method for driveability is proposed by achieving a synthesis between the values calculated from each criterion and the correlated weighting factor obtained from the regression analysis of the subjective evaluations. The results by the proposed method with the target HEV are compared to those of the subjective evaluations during acceleration condition and while overtaking. A HEV dynamic model is also designed to utilize the proposed method. The characteristics of two types of strategies for HEVs are designed and analyzed. Finally, a driveability evaluation for each control strategy is performed and the results are compared using the proposed evaluation method.

Prediction and evaluation of working conditions on high-speed craft using suspension seat modelling

Severe working conditions on board high-speed craft adversely affect not only the safety, health and performance of the crew but also the performance of the vessel as a technical system. Human factors–based ship design combined with appropriate vibration mitigation techniques and work routines for the crew can improve the working conditions and reduce the risks for performance degradation and adverse health effects. To enable development and use of such means, methods for prediction and evaluation of working conditions are needed for both existing high-speed craft and craft under design. This article presents a 2-degree-of-freedom seat model compatible with both measured and simulated input data. The interaction between seat and human is treated using the concept of apparent mass. The model is validated against experiment data collected on board a 10-m, 50-knot high-speed craft equipped with high-standard suspension seats. Evaluation measures defined in ISO 2631-1 and ISO 2631-5 are used to compare experiment data to modelled data. The seat model slightly overestimates the experiment Sed dose by a mean of 6.5% and underestimates the experiment vibration dose value (8 h) by 4.0%. It is concluded that model data correlate well with experiment data.

Assessment of whole-body vibration exposures and influencing factors for quarry haul truck drivers and loader operators.

To further assess vibration exposure on haul trucks (HTs) and front-end wheel loaders (FELs), follow-up investigations were conducted at two US crushed stone operations. The purpose was to: 1) evaluate factors such as load/no-load conditions, speed, load capacity, vehicle age, and seat transmissibility relative to vibration exposure; 2) compare exposure levels with existing ISO/ANSI and EUGPG guidelines. Increasing HT speed increased recorded vibration at the chassis and seat as expected. Neither vehicle load nor vehicle speed increased transmissibility. Increasing HT size and age did show transmissibility decreasing. HT dominant-axis wRMS levels (most often the y-axis, lateral or side-to-side direction) were predominantly within the health guidance caution zone (HGCZ). However, several instances showed vibration dose value (VDV) above the exposure limit value (ELV) for the ISO/ANSI guidelines. VDV levels (all dominant x-axis or fore-aft) were within and above the HGCZ for the EUGPG and above the HGCZ for ISO/ANSI guidelines.

The role of motion platform on postural instability and head vibration exposure at driving simulators

This paper explains the effect of a motion platform for driving simulators on postural instability and head vibration exposure. The sensed head level-vehicle (visual cues) level longitudinal and lateral accelerations (ax,sensed=ax_head and ay,sensed=ay_head, ayv=ay_veh and ayv=ay_veh) were saved by using a motion tracking sensor and a simulation software respectively. Then, associated vibration dose values (VDVs) were computed at head level during the driving sessions. Furthermore, the postural instabilities of the participants were measured as longitudinal and lateral subject body centre of pressure (XCP and YCP, respectively) displacements just after each driving session via a balance platform. The results revealed that the optic-head inertial level longitudinal accelerations indicated a negative non-significant correlation (r=−.203, p=.154>.05) for the static case, whereas the optic-head inertial longitudinal accelerations depicted a so small negative non-significant correlation (r=−.066, p=.643>.05) that can be negligible for the dynamic condition. The XCP for the dynamic case indicated a significant higher value than the static situation (t(47), p<.0001). The VDVx for the dynamic case yielded a significant higher value than the static situation (U(47), p<.0001). The optic-head inertial lateral accelerations resulted a negative significant correlation (r=−.376, p=.007<.05) for the static platform, whereas the optic-head inertial lateral accelerations showed a positive significant correlation (r=.418, p=.002<.05) at dynamic platform condition. The VDVy for the static case indicated a significant higher value rather than the dynamic situation (U(47), p<.0001). The YCP for the static case yielded significantly higher than the dynamic situation (t(47), p=.001<0.05).

Correlation between Whole Body Vibration Exposure and I-Kaz&lt;sup&gt;TM&lt;/sup&gt; 3D Coefficient for Malaysian Army 3-Tonne Truck Drivers

Exposure to high levels of whole body vibration (WBV) from the seat can present risks to health and safety and cause injuries to drivers. This study presents a study on WBV exposure to Malaysian Army 3-tonne truck drivers using the method defined in International Standard ISO 2631-1:1997. The vehicle that was chosen for this study was based on the highest number of vehicles available within the Malaysian Army services. 3-tonne truck is the most widely used in Malaysian Army services. WBV from the drivers were measured using tri-axial accelerometer and was connected to Brüel &amp; Kjær Vibration Analyser Type 3649, which is capable to produce raw data to calculate the vibration dose value (VDV). The raw data from each axis were analyzed using statistical analysis method, Integrated Kurtosis Algorithm for Z-notch Filter (I-kazTM) 3D to determine the vibration values in relation to varying speed of the vehicle. Based on the results, WBV experienced by the drivers can be presented in VDV and I-kazTM 3D coefficient which the value will increase proportional to the truck speed.

Evaluating Methods of Vibration Exposure and Ride Comfort in Car

Objective: This paper studies the method of measuring whole-body vibration in the car and terms associated. Background: Human exposure to vibration can be broadly classified as localized and whole-body vibration. The whole-body vibration affects the entire body of the exposed person. It is mainly transmitted through the seat surfaces, backrests, and through the floor to an individual sitting in the vehicle. It can affect the comfort, performance, and health of individuals. Method: Human responses to whole-body vibration can be evaluated by two main standards such as ISO 2631 and BS 6841. The vibration is measured at 8 axes - three translations at feet, 3 translations of hip and two translations of back proposed by Griffin. B&K"s sensors used in this study are the 3-axes translational acceleration sensor to measure the translational accelerations at the hip, back and foot. Results: The parameters associated with the whole-body vibration in the car are frequency weightings, frequency weighted root-mean-square, vibration dose values, maximum transient vibration value, seat effective amplitude transmissibility, ride values and ride comfort. Conclusion: Studied the evaluating methods of vibration exposure and ride comfort. Application: Evaluation of whole-body vibration in the car.

Comparing Health Risks to Load-Haul-Dump Vehicle Operators Exposed to Whole-Body Vibration Using EU Directive 2002/44EC, ISO 2631-1 and ISO 2631-5

The purpose of this study was to evaluate health risks to operators of large and small load-haul-dump (LHD) vehicles exposed to whole-body vibration (WBV), based on criteria established in ISO 2631-1, ISO 2631-5, and EU Directive 2002/44 EC. Studies simultaneously evaluating health risks based on all three standards are limited. Operator WBV exposure was measured in accordance with ISO 2631-1 using a tri-axial seat pad accelerometer. According to ISO 2631-1, four of the seven large LHD vehicle operators and three of six small LHD vehicle operators were exposed to WBV above the 8-hour vibration dose value (VDV) health guidance caution zone (HGCZ). According to the EU Directive 2002/44/EC criteria one of the seven large LHD vehicle operators and one of the six small LHD vehicle operators were exposed to WBV above the VDV daily exposure limit. However, health risks predicted by ISO 2631-5 criteria only placed one of seven large LHD vehicle operators and one of the six small LHD vehicle operators in the high probability of an adverse health effect category. Thus, the probability of adverse health effects, associated with WBV exposure during LHD vehicle operation, is suggested to be greatest based on the ISO 2631-1 8-hour VDV HGCZ and lowest based on ISO 2631-5 Sed criterion values.

Vibration characteristics of mining equipment used in Indian mines and their vibration hazard potential

Aims: This study aimed to monitor the vibration levels of mining machinery and duration of exposure to vibration; to study work practices of operators of mining machineries and to predict health risk from vibration exposure to operators. Materials and Methods: Vibration levels of 157 mining equipment including dumpers, dozers, etc. in 10 opencast mines were measured through accelerometer and recorded in vibration analyzer. Root mean square (RMS) values of acceleration as well as vibration dose values along with duration of exposures per day were used to predict health risk in accordance with ISO 2631-1:1997 standard. Video records of equipment operation were used to analyze job components. Results: Health risk was evaluated using RMS acceleration (0.21-1.82 m/s 2 ) and corresponding daily durations of exposure (2-7.5 h). Forty two (27%) of the equipment showed minimal health risk, 83 (53%) equipment showed moderate and 32 (20%) equipment showed high health risk to operators. While shovels and excavators showed minimal health risk, dozers and dumpers showed high health risk potential. x-axis was the dominant axis of vibration for loaders and dozers, whereas for the majority of dumpers and tippers, z-axis was dominant. Conclusion: Dumpers require engineering control for reducing the vibration in z-axis while measures are required for x-axis in loaders or dozers. Shovels or excavators do not require immediate attention except regular monitoring. Improvement in work practices are required to safeguard the workers from vibration related illness. It is recommended that proper guidelines for measurement and control of vibration at workplace should be formulated.

Optimisation of acoustical comfort in vehicle cabin using the goal programming

Car cabin acoustical comfort is one of the main features that may attract customers to purchase a new vehicle. The noise in a passenger car cabin is closely related to the vibration generated in the vehicle system. In this study, the effects of vibration on noise in the passenger car cabin have been studied. The vehicle acoustical comfort index (VACI) was used to evaluate the noise annoyance level and the vibration dose value (VDV) was used to evaluate the vibration level. Because engine noise is one of the dominant sources of interior noise, an approach has been used to study the correlation between engine speed and the level of generated vibration. According to the changes in the noise and the vibration level as a function of engine speed, a goal programming model was used to optimise the noise annoyance level in the passenger car cabin. At the end of the study, a multi-objective model was successfully built to optimise the noise annoyance levels by looking at the required vibration dose value at certain engine speeds.

Formulation of Weighted Goal Programming Using the Data Analysis Approach for Optimising Vehicle Acoustics Levels

Two factors for customers to consider when purchasing a vehicle are the vehicle acoustical comfort and the vibration in the vehicle cabin, both of which contribute to a comfortable driving environment. The amount of discomfort is included by frequency, magnitude, direction, and the period during which the noise is experienced and also where the vibration is experienced in the cabin. The main sources of vibration that have been identified previously are the vibration transmitted from engine and the vibration transmitted from the interaction of the tires with the road surface. In this study, we investigate the effect of the vibration caused by the tire interaction with the road surface by estimating the amount of noise produced due to this phenomenon. The methodology focuses on the trends which occur in the noise exposure and on the vibration exposure that has been generated throughout the engine operating rpm range in both stationary and non-stationary conditions. The vibration dose value (VDV)f was used to assess the amount of vibration exposure that is transmitted to the driver’s body in the cabin. Through the study, we have proved that the vibration caused by the tire-road surface contact is a major contributor to the cabin’s interior noise. Based on the results, a goal programming method was developed to optimise the noise levelin the cabin by considering the vibration as an input in the model. Finally, a multi-objective goal programming was developed successfully which could be used to optimize the noise level in the cabin by looking at the value of the VDV required at particular engine speeds (rpm).

Vibration analysis of the sulky accessory for a commercial walk-behind lawn mower to determine operator comfort and health

A sulky is a single-wheeled platform attachment on which the operator of a commercial walk-behind lawn mower rides while standing. The effects of sulky vibration on operator comfort and health have not been investigated. In this study, tri-axial accelerometers measured sulky vibration during mower use by two commercial mowers on varied terrain and 12 volunteer mowers over a controlled course. The accelerometer data were processed according to methods established in ISO 2631. Results indicate the mean frequency-weighted root mean square (RMS) acceleration sums fall into the ‘very uncomfortable’ range for vibration of standing persons (1.9 ± 0.48 m s−2). Additionally, vibration dose values indicated that the mean vibration dosages exceeded the daily exposure limit values established in Directive 2002/44/EC (z-axis A(8) value of 1.30 ± 34 m s−2; VDVexp value of 28.1 ± 6.25 m s−1.75). This information suggests that modifications including vibration damping should be added to the sulky to reduce rider discomfort and health risks. Practitioner Summary: This study investigated the effects of vibration during use of a commercial lawn mowing sulky. Findings from accelerometer data suggest that the vibration experienced by sulky operators is significant enough to cause discomfort and health risks which may lead to personnel turnover or long-term effects for the operator.

Evaluation of Whole-Body-Vibration Exposure to Cairo Subway (Metro) Passengers

air, land and water), machinery (for example, those used in industry and agriculture) and industrial activities (such as pilling and blasting), expose people to periodic, random and transient mechanical vibration which can interfere with comfort, activities and health. Metro is one of the important and famous public transportations all over the world. High magnitude of whole-body vibration formed by the Metro may cause diseases and health problems to the human especially a low back pain. It leads to a muscular and bone system disorder of the neck and back. A previous epidemiological study reported that low-back pain (LBP) is spread among people exposed to whole-body-vibration frequently. LBP was significantly related with the levels of uncomfortable road vibrations, and, importantly, increased with total mileage. The aim of this study is to give an account of daily exposure to vibration and vibration dose value exposed to the passengers travelled using Cairo metro by measuring the whole body vibration on the passenger's seat pan (seat back and seat surface) and on the floor. The results were evaluated according to the health guidelines of the international standards ISO 2631-1:1997, Directive 2002/44/EC of the European Parliament and ISO 2631-5:2004. damage or physiological change). The presence of oscillatory force with little motion may cause similar effects. The effects of direct vibration on the human body can be serious. Vibration can typically cause blurred vision, loss of balance, loss of concentration etc. In some cases, certain frequencies and levels of vibration can permanently damage internal body organs. After daily exposure over a number of years, these same whole-body vibrations can result in a number of health disorders affecting your entire body including permanent harm to internal organs, muscles, joints and bone structure. Research indicates back disorders are more prevalent and more severe in exposed to vibration versus non-exposed. With short term exposure to vibration in the 2-20 Hz range at 1 m/sec 2 , one can feel several different symptoms like, (16) abdominal pain, general feeling of discomfort, including headaches, chest pain, Loss of equilibrium (balance), muscle contractions with decreased performance in precise manipulation tasks, shortness of breath, and influence on speech.

EUROPEAN AND RUSSIAN METHODS FOR EXPOSURE ASSESSMENT APPLIED ON WHOLE BODY VIBRATION VALUES IN SHORT HAUL DUMP TRUCKS

Operating Surface Haul Trucks (SHT) exposes mineworkers to whole body vibration (WBV), but risk assessment methods are not uniform in the Barents Region. We intended to measure WBV exposure from SHT, and discuss and compare risk assessment outcome by European and Russian methods. 17 WBV measurements were performed at the operator seat interface on 14 SHTs in an open cast mine in Northwest Russia. Measurement periods ranged from 13 to 58 minutes in real work cycles during 8 hours of driving. It was found that mean WBV exposure (A(8) rms) for the 14 SHT’s was (1.0 ± 0.23) m/s 2, mean crest factor - (12.78 ± 5.26) and mean vibration dose value - (10.35 ± 2.61) m/s 1· 75. The study shows that WBV levels defining the lower limit of hazard class 3.2 (Russia) is close to the limit value 1.15 m/s 2 (European countries).

Health risks associated with whole-body vibration exposure in steel manufacturing vehicle operators

The purpose of this study was to measure operator exposure to whole-body vibration (WBV) and to determine health risks associated with the operation of heavy-lift transporters (HLT; n=2), pot haulers (n=3), hoists (n=4) and loaders (n=2) used within the steel manufacturing industry. Anecdotal evidence suggested operators of the above equipment were suffering from vibration-induced injury; however, typical exposure data was not available in the literature. A tri-axial seat-pad accelerometer was used to measure vibration at the operator/seat interface. Health risk to operators was determined based on criteria established in the ISO 2631-1 standard. The calculated 8-hour daily equivalent vibration dose value placed all pot haulers and one HLT, one hoist and one loader above the health guidance caution zone (HGCZ). Therefore, interventions aimed at reducing vibration exposure below the ISO 2631-1 HGCZ should be implemented. Caution must be applied when generalizing exposure data to other industries; however, exposure data reported in this study does represent the first published data for pot-haulers and HLTs in steel production.

Exploring how anthropometric, vehicle and workplace factors influence whole-body vibration exposures during on-farm use of a quad bike

The primary aim of this study is to determine whether a combination of body height, terrain and vehicle mechanical factors confound for the effect of body mass on WBV exposure while using a quad bike under normal rural working conditions. A seat pad mounted triaxial accelerometer and data logger recorded full work day vibration and shock data from 130 New Zealand rural workers. Personal, vehicle and workplace characteristics were gathered using a modified version of the Whole Body Vibration Health Surveillance Questionnaire. Whole-body vibrations were analysed in accordance with the ISO 2631-1 and ISO 2631-5 standards and it is presented as one hour vibration dose value in the Z-direction (1 h VDVZ). Body mass did not demonstrate any significant bivariate association (P > 0.20) with 1 h VDVZ. However BMI, body height, vehicle weight, sheep farm, dairy farm, 2 shock absorber solid axle rear suspension, flat farmland and engine capacity (cc) all demonstrated threshold bivariate associations (P ≤ 0.20) with 1 h VDVZ. Body mass, body height, 2 shock absorber solid rear axle suspension, and working on a sheep farm created the strongest multiple regression model explaining 16% of variance in VDVZ. Relevance to industryThe influence of driver's body mass on vibration exposure is strongly influenced by work environment and vehicle mechanical factors and this should be taken in to consideration for research that explores exposures and/or designing seating and suspension systems to attenuate vibration exposures in small on-farm vehicles.

Whole Body Vibrations Exposure to Malaysian Driver Using Novel IKaz Method

A car is a wheeled motor vehicle used for driving and transporting passengers. Therefore, cars are one of the most important forms of transportation worldwide. However, high magnitude of whole-body vibration (WBV) that can be associated with the car may lead to various diseases and health problems, such as low back pain, in humans. This study intended to present the value of Daily Exposure to Vibration A(8) and Vibration Dose Value (VDV) experienced by the car driver, with care taken to elucidate the effects of WBV on the human body. In addition, this study is done to implements a newly developed statistical analysis method called I-kaz 3D to determine the vibration level accordingly. The high value of I-kaz 3D coefficient corresponds to the high VDV value and otherwise. This study was conducted on a national car. The WBV exposure was measured for 10 min. Data was collected using an IEPE(ICPTM) accelerometer sensor connected to a DT9837 device, capable of effectively measuring and analyzing the vibration. The vibration results were displayed on a personal computer using a custom graphical user interface (GUI). From the results gathered, it is confirm that WBV absorbed by the human body increases with an increase in the duration and magnitude of vibration exposure by the driver, illustrated by the increase in the value of daily exposure to vibration A(8) and the calculated vibration dose value (VDV).