Assessment of adjustable damping in the ride comfort of a baja SAE vehicle
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(2020) 42:583
TECHNICAL PAPER
Assessment of adjustable damping in the ride comfort of a baja SAE vehicle Leonardo Roso Colpo1 · Carlos Eduardo de Souza1 Received: 4 June 2019 / Accepted: 1 October 2020 © The Brazilian Society of Mechanical Sciences and Engineering 2020
Abstract The paper presents a case study of a small off-road vehicle and its response to ground excitations regarding the geometrical suspension properties and the variation of adjustable damping parameters, that can change restoring force in fast bump, slow bump and rebound zones. The shock absorber behaviour in force–velocity graphs is obtained from experimental data and introduced in the simulation by a lookup table strategy, without a mathematical model describing the damping behaviour. The analysis is done through a seven degrees-of-freedom model, describing the full vehicle, and assembled in a state space form. Ground excitations are inserted as wheel displacement from random road vibrations and a single road bump, with the use of a roller contact model. The acceleration transmitted to the driver is compared to comfort standards to verify possible discomfort or danger to health damages in long exposure. The outputs are validated with linear potentiometers, showing that the model can accurately predict the shock absorbers behaviour and, consequently, the accelerations transmitted to the driver. To the shock absorbers studied, low bump velocities do not affect significantly exposure risk to vibrations and present a small comfort improvement. Otherwise, through road bumps, a softer regulation ensures a better performance, reducing sprung mass displacement in 31% and accelerations transmitted in 33% at the shock absorber regulation range. Keywords Passive suspensions · Experimental damping · Noise/vibration · Comfort · Off-road vehicle
1 Introduction All road vehicles interact with the ground by the tires contact, that transmits to the chassis the excitation due to the track profile. The suspension system has the main function to attenuate those excitations to provide ride comfort [1], since the vibrations felt by the driver are very related to comfort, being this a main contributing factor to vehicle purchase decision and satisfaction [2, 3] in the case of commercial vehicles. The study of suspension performances is usually approached by the construction of mathematical models representing the vehicle and its properties [4], considering very simple models with two degrees-of-freedom models in quarter-car models [5–7], or increasing the model size to
Technical Editor: Marcelo Areias Trindade. * Leonardo Roso Colpo [email protected] 1
Federal University of Santa Maria, Av. Roraima nº 1000, Santa Maria, RS 97105‑900, Brazil
represent the full vehicle [4, 8–11], aiming to explore the effect of excitation on other points on the ride model. Most recent works go further on suspension control by implementation of active and semi-active systems, often with the use of magneto rheological dampers [8, 12, 13] which can considerably reduce t
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