Study of the dynamic response of a quarter car model coupled with a human passenger for different speed bumps profiles

Abstract

This work proposes a three-degrees-of-freedom Human-Vehicle-Road model to study the system’s dynamic as a response to road-induced excitations and evaluate the effect of vibrations on ride comfort. The study of the dynamic responses of the system is concerned only with the vertical motion of the passenger, sprung mass, and the tire when subjected to different excitation profiles. The model of the human is developed based on literature and then coupled to a quarter-car model using analytical methods. The mathematical model that describes the motion of the system is derived using Newton’s law of motion. The numerical simulations of the mathematical model using MATLAB provide the basis for the ride comfort analysis. The effects of the bump geometry are also studied in terms of the amplitude of each displacement, velocity, acceleration, and transmitted force. The ride comfort analysis is based on the ISO 2631 and BS6841 standards. The new concept of bump rotation is introduced and discussed in comparison with previous results. The investigation of the angle of rotation is presented as a totality of case studies where the bump is rotated with respect to the x-axis from 0 to 75° which is equivalent to a longer bump while maintaining the same height. The dynamic response for all rotation angles is collected to show that longer bumps have better performance because they reduce the forces transmitted to the system while maintaining the required level of discomfort to control the speeds of vehicles on roads. The ride comfort analysis concludes that the cycloidal bump has better performance as a speed control device.