Review on vibration quality improvement of a passenger seat (original) (raw)
Related papers
Automotive Seat Comfort and Vibration Performance Evaluation in Dynamic Settings
Applied Sciences
An automotive seat is a key component which not only provides restraint and support for its occupant, but also mitigates vibration. Since an automotive seat is in constant contact with the vehicle occupant, its dynamic comfort is of great importance in automotive seat designs. In this study, three automotive seats with different foam firmnesses were evaluated to understand how the foam firmness, through different foam formulations, affected the seat vibration performance and perceived dynamic comfort in a laboratory (study 1) and field setting (study 2). In a repeated-measures laboratory based study, whole-body vibration (per ISO 2631-1), self-reported body discomfort, and seating comfort were measured and compared among the three automotive seats while participants were exposed to tri-axial, field-measured, automotive vibration and X-Y-Z axis 1–30 Hz sine sweeps. In a subsequent ride-and-drive field study, the two seats that received the highest comfort ratings from the laboratory ...
Vibration Comfort of the Vehicle Expressed by Seat Effective Amplitude Transmissibility
Mobility and Vehicle Mechanics
Research of the human body vibrations, carried out under controlled laboratory conditions, shows that human body is the most sensitive to vibrations in the frequency range that matches the biomechanical resonance. In the vertical direction, the resonance of the body is approximately 5 Hz, while in the horizontal direction the resonance occurs at frequencies less than 2 Hz. The vibrations of the vehicle have been transferred to the driver and passengers over the seats, which have the ability to attenuate or to amplify vibrations which human body is exposed to while driving. One way to determine the vibration behaviour of the seat is to measure the SEAT (seat effective amplitude transmissibility) factor, which represents the ratio between the vibrations measured on the seat and vibration measured directly on the floor under the seat. Measurement of vibrations in these two positions must be performed simultaneously. If the value of SEAT is less than 1, a seat attenuates vibrations and meets vibrational comfort, the value of SEAT greater than 1 indicates that a seat amplifies vibration, reducing vibration comfort. This paper gives results of SEAT factor investigation done on a hybrid vehicle, for different types of road surface and different modes of driving (electric power and internal combustion engine).
Dynamic Comfort Testing of Automotive Seats in a Laboratory Setting
2021
The goal of this study was to use three identical looking automotive seats with different foam formulations (different stiffness, similar hysteresis) to determine whether there were differences in WBV exposures and self-reported comfort ratings across the three seats (Seat A, B, and C). Ten participants (5 male; 5 female) were recruited for this repeated-measures laboratory study. The seats were mounted on a 6 degree-of-freedom (DOF) vibrating platform on which the participants were exposed to sinusoidal vertical (Z-axis) and field-measured, tri-axial car floor vibration profiles. The participants ranked their seat preference before and after using all three seats. Self-reported seat comfort was evaluated using 7-point Likert scales at the end of each seat test. Results indicated that the least stiff seat C had the lowest resonance frequency and the lowest WBV magnitudes across all road types. Seat C was also the most preferred among the participants. This study indicates that it ma...
Evaluation of Whole-Body Vibration and Ride Comfort in a Passenger Car
Whole-body vibration transmission influences comfort, performance, and long-term health of the driver. This current study is an objective evaluation of vehicle comfort characteristics based on standard mathematical formulae and frequency analyses. A variety of road types were selected and quantified by using the International Roughness Index (IRI). To assess vibrations transmitted to the passengers, vibration dose values (VDV), kurtosis, frequency response functions (FRF), and power spectral densities (PSD) of the compartment recorded signals were evaluated. SEAT values based on VDV outputs qualified the seat suspension as a vibration isolator, whereas the FRF and PSD quantified that behaviour through frequency analyses. Results indicate that energy concentration is at frequencies lower than 30 Hz. Such low frequency excitations are well attenuated by seat suspension in the vertical direction but are amplified (up to five times in harsh conditions) by a backrest in the fore-aft trend. Signals are amplified beyond 30 Hz, but amplitudes are still very low. It seems that backrest assembly still can be improved to become a better isolator. However, T15 (time to reach severe discomfort), even in harsh conditions, is more than three hours, which exhibits the overall good quality of the vehicle suspension systems. Kurtosis and VDV correlate with IRI and may be used as two objective metrics, together with jury evaluation, to create a vehicle vibration-comfort index in the future.
Istrazivanja i projektovanja za privredu, 2017
The paper analyzed the infl uence of the passenger seat's cushion oscillatory parameters (stiffness/damping) on ride comfort and dynamic seat comfort. The analysis was done using a linear in-line oscillatory seat-human model with 4 degrees of freedom (DOF) defi ned in Matlab/Simulink. For the oscillatory excitations of the in-line model, the vertical accelerations of the bus fl oor under the users' seats were used. Bus fl oor accelerations were obtained by simulation using validated spatial oscillatory intercity bus model with 65 DOF defi ned in the ADAMS/View software. The ride comfort was assessed by the criteria of ISO 2631/1997 standard. The seat effective amplitude transmissibility (SEATrms) parameter was considered for analyzing the dynamic seat comfort. It was found that passengers in the rear part of the bus had a lower level of ride comfort than the passengers in the front part of the bus. The intensities of the bus fl oor vertical accelerations for the rear part were mainly concentrated in the frequency range of 5-10 Hz. Passengers at the rear had lower SEATrms values than those at the front. The SEATrms values increased noticeably with the increase in the cushion stiffness, but those values were below 100% for all considered users. Increase in the cushion damping slightly decreased SEATrms values.
The effect of seat design on vibration comfort
International journal of occupational safety and ergonomics : JOSE, 2003
A field study was done to evaluate different seat designs in the aspect of minimizing vibration transmission and reducing the level of discomfort experienced by drivers subjected to transient vibration. Two seat designs (sliding or fixed in the horizontal direction) were compared in an experiment based on variation of sitting posture, speed, and type of obstacle. The comparison was done by assessing discomfort and perceived motion and by vibration measurement. Ten professional drivers were used as participants. Maximum Transient Vibration Value and Vibration Dose Value were used in the evaluation. The results showed that a sliding seat is superior in attenuating vibration containing transient vibration in the horizontal direction. It was also perceived as giving less overall and low back discomfort compared to a fixed seat.
Assessment of the vibration on the foam legged and sheet metal-legged passenger seat
Metalurgija, 2016
L. Dahil, Istanbul Aydın University, Department of Mechanical and Metal Technologies, Turkey. A. Karabulut, Afyon Kocatepe University, Faculty of Technology, Mechanical Engineering, Turkey. In this study, it was aim ed to decrease the vibration reaching to passenger from the legs of vehicle seats. In order to determine the levels of vibrations reaching at passengers, a test pad placed under the passenger seat was used, and HVM100 device was used for digitizing the information obtained. By transferring the vibration data to system by using HVM100 device, the acceleration graphics were prepared with Blaze software. As a result, it was determined that the acceleration values of seat legs made of foam material were lower than that of seat legs made of 2 mm thick sheet metal, so they damped the vibration better.
Vibrational Characteristics of Tractor Seat Cushion Materials and Ride Comfort
Journal of Low Frequency Noise, Vibration and Active Control, 2002
Tractor seat design can be used as a means to modify loads on body structures to reduce operator's discomfort. The overall comfort and performance of the tractor seating system consist oi fi-ame. cushion. covers. suspension and damping mechanisms. Vibration attenuation in a tractor seat is achieved by selecting the proper suspension and damping mechanism. The vibration characteristics of cushion materials are often overlooked. This paper describes a method of vibration characterisation of tractor seat cushion materials to improve operator's comfort. Nine commercially available seat cushion materials of different density, thickness and composition were randomly selected for this study. Transmissibility data were obtained by measuring input acceleration values on the base plate and output acceleration values at mass at different frequencies from 1 to 7 Hz. It was observed that vibration transmissibilities at resonance and the resonance frequency were significantly affected by ...
Evaluation of Human Discomfort from Combined Noise and Whole-Body Vibration in Passenger Vehicle
International Journal of Automotive and Mechanical Engineering
Exposure to noise and whole-body vibration (WBV) has been a key element in determining comfort levels in transportation systems. In the automotive industry, researchers and engineers continuously work on reducing noise and vibration levels to minimize discomfort. Noise annoyance in vehicles results from structure-borne as well as air-borne noise from vehicle powertrain, tires and aeroacoustics. Whole-body vibration affects vehicle passenger comfort at the seat pan, back rest and feet. The objective of this research is to evaluate the comfort level of seated passengers in a vehicle from noise and whole-body vibration by considering both separate and combined modality. The noise and vibration data were recorded and analysed in two vehicles on the same highway road with four different speeds. The vibration exposure in vehicle were evaluated based on ISO2631-1:1997. Noise exposure was based on A-weighted sound pressure level. The combined discomfort on noise and vibration were quantifie...
An experimental investigation of the vibrational comfort of child safety seats
2003
The research of this thesis was performed to understand the vibrational dynamics of stage 0&1 child safety seats and of the children who occupy them. Since no previous vibration data for small children or child seats was found, the investigation took the form of experiments designed to shed light on the behaviour of the system consisting of child, child seat, vehicle safety belt and vehicle seat. To provide a background for interpreting the results a literature review was performed of child seat characteristics, of human whole-body response and of primate whole-body response. An industrial test procedure for measuring the vibration isolation properties of vehicular seats is also presented as an illustration of the concepts involved. A whole-body vibration bench for testing children in the vertical direction was built and apparent mass and absorbed power functions were measured for 8 children of age less than 24 months and mass less than 13 kg. An algorithm was developed for identifying the parameter values of a single degree of freedom mass-spring-damper model of the seated body using Differential Evolution optimisation. The parameter values were determined for each child and compared to those of adults and primates. This thesis also presents the results of modal testing of 2 child seat units and of operational deflection shape testing of 1 unit in an automobile under 3 loading conditions (empty, sandbag or child). In-vehicle transmissibility measurements were also performed in the vertical direction for 10 children and child seats using 9 automobiles. The floor-to-human transmissibilities were determined for each child and driver when passing over a reference road surface at both 20 and 40 km/h. Except for the damping ratio, all child mechanical response parameters were found to differ with respect to those of adults or primates, with the differences being greater with respect to adults. The first resonance frequency of children was found to be located at 8.5 Hz as opposed to 4.0 Hz for adults, raising questions regarding the applicability of standards such as ISO 2631 towards the evaluation of child vibrational comfort. The child seats were found to have higher transmissibilities on average than the vehicular seats occupied by adults. A characteristic low frequency rigid body rocking motion was noted at 1.8 Hz as were multiple flexible body resonances starting from frequencies as low as 15 Hz. Areas of possible improvement and topics for further research have been identified.