Análise de desempenho de suspensão convencional e hidropneumática considerando a variabilidade dos parâmetros

Abstract

Deterministic values are largely used in mechanical design to define the parameters which describe the system. Large coefficients of safety are used because of the uncertainties related to these parameters. There are uncertainties related to the external loadings, to the variability of the material properties and to the environmental conditions, among other important parameters which affect the performance of the system. In the last decade, stochastic models have been used to consider these uncertainties and variations. The present work analyzes the effect of the simultaneous variability of certain parameters on the performance of the conventional and the hydropneumatic suspension of automotive vehicles. A mathematical model of a full vehicle with seven degrees of freedom has been used. This model was implemented in the software Matlab ® . In the present formulation of the hydropneumatic suspension, it is considered that the gas contained in the accumulator undergoes a polytrophic process. First, the deterministic model of the vehicle is subjected to two transient excitations, namely a function describing a bump and a function describing a step with different dimensions. Then, an analysis of sensibility of the stiffness of the hydropneumatic suspension is performed, which aims to identify which parameters are the most influential on that system. Monte Carlo method is used as the stochastic solver throughout the simulations which study the influence of the parameter variability on the vertical dynamics of the vehicle. The Gamma function is used as the probability density function for each parameter. Finally, the response of the probabilistic models is studied. This work investigates the acceleration of the center of gravity, damping factor, pitch angle of the suspended mass and contact force between the tires and the road.

Aplicação da Simulação Hardware in the Loop para testes e desenvolvimento de suspensões veiculares

“…elas estão: barra de torção, feixe de molas, molas helicoidais, molas pneumática e molas hidropneumática (REIMPELL et al, 2001)(BALDI, 2004);(PIVETA, 2012).…”