Multi-link Suspension System K&C Characteristics Analysis And Vehicle Handling Evaluation Study Of Zhongqi Sedan

Along with the increasing demands for the improvement of automotive performance, how to elevate vehicle handling under high-speed effectively becomes a hot issue in automotive industry nowadays. Suspension system, which affects vehicle's behavior directly, is one of the key points in the R&D process of automobiles.This thesis is one of the sub-projects in the national major project "Independent Creative Capability-construction of High-level Automobile China", focusing on the performance analysis of the front four-link and rear trailing-arm four-link suspension system equipped on Zhongqi sedan, and determine proper objective evaluation indexes of handling for the discussion of the chassis parameters affecting vehicle's dynamical behavior. The study will provide theoretical basis as well as engineering guidance for the later design improvement and vehicle tuning.In the initial pahse, front four-link, rear trailing-arm four-link suspension system model were estabilished in ADAMS/Car. The model, which thoroughly considered the components mechanical characteristics such as bushing, has relatively high precision and completeness. Then the K&C (Kinematics & Compliance) analysis of front and rear suspension system was conducted in detail. The results showed excellent performance of the system.Next, a complete dynamical model of Zhongqi sedan was built in CarSim software for the convenient discuss of the chassis parameters. Meanwhile, the tire experiment data was fit using Magic Formula tire model, which improves the accuracy of the model effectively.Afterwards, the comparison and analysis of several relatively complete objective assessment system of handling in China and aboard were performed, and a new objective evaluation system of handling and stability which can be applied to Zhongqi sedan was brought out after combining the research results recent years. The system, which covers vehicle's characteristics in steady-state, transient time domain as well as frequency domain, has relatively high completeness.The thesis then discussed multi chassis parameters affecting vehicle handling thorougly. These parameters, which involved ten aspects, were divided into two categories:1. Parameters affecting wheel loads, including 4 aspects which are weight distribution, roll stiffness distribution, shock absorber damping ratio, shock absorber C/R ratio (compression/rebound damping ratio).2. Parameters affecting wheel alignments, including 6 aspects which are steering compliance, static toe, roll steer, lateral force steer, static camber, roll camber.Finally, synthetically comparison of the parameters in the two categories above was carried out, and a sensitivity table of each handling index to each chassis parameter was determined as a reslut. Then the chassis parameters of Zhongqi sedan were re-set partly, according to the sensitivity table. Comparison showed distinct elevation of the handling and stability of Zhongqi sedan.