Research On Dynamic Characteristics Of Vehicle Suspension System Under The Action Of Non-linear Damping And Its Application

Suspension system is an important part of the vehicle. It is the key component for riding comfort and stability. Now with the requirement for vehicle performance increasing continuously, the linear suspension system already cannot satisfy the requirement of people. So, it seems especially important to research and analyse the nonlinear suspension system. In recent years, dynamic characteristic research of non-linear suspension system is already becoming a significant subject in the field of vehicle suspension research. Build automobile nonlinear suspension model, and carry out an in-depth study by using modern nonlinear dynamics theory, these mean the important significance to further reveal vibration law of vehicle suspension.This research is financially supported by the National Natural Science Foundation of China "The research of mechanical fault diagnosis based on nonlinear theory in the weak signal detection and treatment technology"(NO.50875070). The dissertation studies mostly the two-DOF suspension model with damping non-linear characteristics. The dynamical characteristic is studied by the means of modern nonlinear theory and chaos theory. The dynamical behaviors are described by using numerical methods such as time-course curve, phase plane plot and poincare section. Non-linear is the necessary condition of chaos. To judge system fault with studying the mechanism of chaos phenomena is a reverse thinking method of fault diagnosis. It is qualitatively analysed in this paper. The main work of this thesis have been studied as fallows:In the first chapter, based on the systematic and extensive reading of the literatures, we preliminarily review the research situations of automobile suspension nonlinear, nonlinear system theory and chaos theory. The dynamic characteristics research of vehicle suspension system with two-DOF under the action of non-linear damping is presented. In the chapter, the study object and content system of the paper were established. The second chapter introduces the nonlinear system and chaos theory. It provides theoretical basis of the paper’s work. In the third chapter, vehicle suspension model with non-linear damping characteristics is established. The dynamic differential equation is gained, which is piecewise linear ordinary differential equation. In order to facilitate research, the dimensionless equation is obtained. It provides equation foundation for following system dynamic characteristics study. The fourth chapter is the focus of this article. Theoretical analysis and detailed numerical calculation of the mathematical model established in chapter three have been gone in the paper. Using numerical methods such as time-course curve, phase plane plot and poincare section, dynamic characteristics of suspension system under different parameters are obtained by MATLAB software’s calculation. From the analysis, we know the system did not go into a chaotic state, but has been in a state or quasi-periodic state cycle. This goes to prove the reasonable of shock absorber’s damping piecewise linear curve in this paper, on the other hand, it is a very good interpretation of the question "Why oscillating damper which cohere with this curve is widely used in automobile suspension?". Chapter V focuses on the development of fault diagnosis technology at home and abroad and study conditions, through the fault diagnosis method based on chaos research, and chaos theory applied to fault diagnosis in mechanical systems, received a kind of vehicle suspension system fault diagnosis method of qualitative analysis, provides a research ideas for the future fault diagnosis system. Chapter VI is a summary of the paper, pointing out the shortcomings of the paper and future direction of development.