Vertical Vibrations of the Vehicle Excited by Ride Test (original) (raw)
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Analysis of the vertical vibration effects on ride comfort of vehicle driver
Journal of Vibroengineering, 2012
Vehicle vibrations affect the health and comfort of the driver and passengers considerably. The aim of this study is to analyze the effects of vertical vehicle vibrations on the driver. To achieve this goal, a human biodynamic model with 11 degrees of freedom was incorporated into a full vehicle model and this combined human-vehicle model was subjected to the road disturbance. After dynamic analysis of the proposed model, root mean square (RMS) acceleration responses of the human body parts over a certain frequency range were obtained. Physiological effects of the vibrations on the human body were analyzed using the criteria specified in International Organization for Standardization (ISO) 2631. Then, in order to observe the effectiveness of a controller on the vibration isolation of human body, sliding mode controller was applied to the model. Comparison of the vibration effects for the uncontrolled and controlled cases of the human-vehicle model was presented. It can be concluded from the results that sliding mode controller considerably reduces whole body vibrations compared with the uncontrolled case and thereby improves the ride comfort satisfactorily.
Pertanika Journal of Science & Technology, 2021
The main reason that affects the discomfort in a driving vehicle is the vibration response. The human body vibration leads to many malfunctions in both comfort and performance in human health. As a result, the human body’s simulation in sitting posture in the driving vehicle has a strategic relationship for all Tires and vehicles manufacturers. The digital process simulation of the human body seat vehicle vibration shows two significant advantages. The first advantage is the prevention of the high-cost modifications in the construction stage of the vehicle, while the second one describes the stability test during the undesirable vibrations. This study modelled the human body’s dynamic characterisations, natural frequency, and mechanical response when seated in the driving vehicle with vibration transmissibility in the vertical direction have been using the biomechanical vibration model. The vertical vibrations and the transmissibility of the human body dynamic response are presented in detail. Exciting results have been obtained, and they are significant for human health, which relates to sitting posture in the driving vehicle. It can assist in understanding the influences of low-frequency vibration on human health, comfort, and performance, and therefore it could be applied for ride comfort evaluation. An analytical solution to derive the general equations of motion for the human system was developed. Then, using the vibration analysis technique and the corresponding equations, the accurate dynamic response of the selected mode is identified. Furthermore, the mathematical modelling for free vibration using the finite element analysis has been performed to determine the appropriate values and set its description. Then, the comparison results of the two techniques have been carried out.
Road Roughness and Whole Body Vibration: Evaluation Tools and Comfort Limits
Journal of Transportation Engineering, 2010
An important element of achieving quality in a road network is the control of vehicle vibration due to pavement roughness and road irregularities. Scientific literature and international standards suggest that we evaluate these phenomena by measuring the WBV (Whole Body Vibration) on the road user, but, for the practical aims of road engineering, this expression has to be related to road unevenness indexes, especially the most common one (the IRI, International Roughness Index). This index, in turn, is obtained from measured pavement geometric data using a conventional model of a mechanical system representing part of a vehicle. To better investigate the problem of user comfort, more complex models and analyses are needed.
Study of the dynamic behaviour of a human driver coupled with a vehicle
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2014
In this paper a 15-degree-of-freedom human–seat vibratory model is developed using anthropomorphic modelling and the model is coupled with a typical seven-degree-of-freedom small passenger car to study the dynamic response of a human driver due to vehicle vibrations. The coupled model is analysed by MATLAB simulation for the ride dynamic behaviour of the human driver under a harmonic input excitation in the frequency range 0–40 Hz. The ride behaviours in terms of the vertical accelerations of different segments of the human driver are compared with respect to the ride comfort using the ISO 2631-1:1997 standard. Further, parametric analysis is carried out to improve the ride comfort of the human driver.
The displacement response of different masses of half car model. The analysis has been done for different car models also to see the dynamic response of the driver body coupled with the seat of a vehicle. It has been assumed the driver body is rigidly coupled with seat of the vehicle. The vehicle has been modeled for two D.O.F, in two D.O.F Half car model two motion (Pitch and Bounce) have been considered. The response of the vehicle has been obtained for different velocities and different amplitudes sinusoidal bump excitation.
The displacement response of different masses of half car model. The analysis has been done for different car models also to see the dynamic response of the driver body coupled with the seat of a vehicle. It has been assumed the driver body is rigidly coupled with seat of the vehicle. The vehicle has been modeled for two D.O.F, in two D.O.F Half car model two motion (Pitch and Bounce) have been considered. The response of the vehicle has been obtained for different velocities and different amplitudes sinusoidal bump excitation.
A straightforward approach is presented to investigate the ride dynamic system for a typical rear-drive passenger car. The procedure is based on introducing two main ride excitation sources, i.e., engine/driveline and road inputs, which reduce passengers' comfort. The measured engine fluctuating torques are applied on the coupled model of the driveline and the suspension, to obtain the vehicle body longitudinal vibration. Further, the body vertical response to an average road roughness, is found by employing the quarter-car model. Through the frequency analysis done in this paper, it is shown that we can fastly determine the transfer functions of the systems and also their forced responses at the desired positions, without guessing any initial conditions for the states. The results illustrate that the high frequency inputs, from the engine, are appropriately damped by the current suspension. Hence, the associated vehicle body longitudinal acceleration meets the International Standard Organization (ISO) criteria. This is not the case for the low frequency disturbances, from the road surface irregularities, where the vehicle body vertical acceleration is above the ISO criteria.
The human body behavior under vehicle vibrations
The influence of vertical vibrations on the human body is analyzed on the basis of models, where the main components and their characteristic properties are made evident. As a function of position of the body, there are considered models, having concentrated masses, elastic constraints and dampers. For a few models that are presented, the matrix differential equations of motion are written and the mathematical input-stateoutput model (M-ISO-M) is specified. On the basis of the adopted mathematical models, computer block diagrams are defined. Thus, for the study of behavior of the mechanical systems, calculus diagrams are elaborated, in order to make evident the connections between the blocks and the developments with the help of Math Lab simulation of the system response to a harmonic input signal. Also with the help of the AnyBody Modeling System software, a driving simulation had been made, resulting intense muscle activities by subjecting the human body to the vehicle vibrations and external forces. The concrete cases that are studied refer to real situations for which the system parameters are deduced by a methodology, previously specified. In each case, fixed by the program running, for each mass, the amplitude-pulsation characteristics are determined, making evident the resonance possibilities.
Influence of Road Excitation and Steering Wheel Input on Vehicle System Dynamic Responses
Applied Sciences, 2017
Considering the importance of increasing driving safety, the study of safety is a popular and critical topic of research in the vehicle industry. Vehicle roll behavior with sudden steering input is a main source of untripped rollover. However, previous research has seldom considered road excitation and its coupled effect on vehicle lateral response when focusing on lateral and vertical dynamics. To address this issue, a novel method was used to evaluate effects of varying road level and steering wheel input on vehicle roll behavior. Then, a 9 degree of freedom (9-DOF) full-car roll nonlinear model including vertical and lateral dynamics was developed to study vehicle roll dynamics with or without of road excitation. Based on a 6-DOF half-car roll model and 9-DOF full-car nonlinear model, relationship between three-dimensional (3-D) road excitation and various steering wheel inputs on vehicle roll performance was studied. Finally, an E-Class (SUV) level car model in CARSIM ® was used, as a benchmark, with and without road input conditions. Both half-car and full-car models were analyzed under steering wheel inputs of 5 • , 10 • and 15 •. Simulation results showed that the half-car model considering road input was found to have a maximum accuracy of 65%. Whereas, the full-car model had a minimum accuracy of 85%, which was significantly higher compared to the half-car model under the same scenario.
Ride Test on Vehicles Travelling Over Speed Bumps: Simulation with CarSim Software
International Journal of Innovation in Mechanical Engineering and Advanced Materials, 2024
This study explores the effects of different speed bump geometries—flat-topped, sinusoidal, and parabolic—on vehicle dynamics and ride comfort using CarSim simulations. The analysis focuses on key parameters such as vertical forces on the suspension, vertical acceleration, and the wheel surface adhesion index. The results show that flat-topped bumps generate the highest vertical forces, reaching peaks of up to 6,000 N on the front suspension, leading to increased discomfort. Sinusoidal bumps, in contrast, generate smoother transitions, with vertical forces peaking at ap-proximately 3,500 N, improving ride comfort. At vehicle speeds of 30 km/h, the vertical forces on the suspension increase significantly, with flat-topped bumps reducing the wheel surface adhe-sion index to as low as 0.6, indicating a higher risk of wheel slip and compromised vehicle stabil-ity. In contrast, sinusoidal bumps maintain a more favorable adhesion index of 0.85 at similar speeds. These reductions in adhesion elevate the risk of loss of control, especially at higher speeds. The findings suggest that adaptive suspension systems, capable of adjusting damping and stiffness based on the bump geometry and vehicle speed, would enhance ride quality and stability. Additionally, smoother bump designs, such as sinusoidal profiles, are recommended to reduce the impact on vehicle dynamics, particularly in urban environments. These insights con-tribute to improving both vehicle design and road safety, ensuring safer and more comfortable driving experiences.