To investigate how the conventional speeds to affect passenger cars ride comfort under a kind of road surface profiles, in multibody dynamics software (ADAMS/Car), a vehicle model was built based on the characteristic parameters of a passenger car. According to the relevant test regulations of ride comfort, the building methods of road surface profiles were discussed. Furthermore, a dynamics simulation analysis of the car was realized by ADAMS/Car and the acceleration-time histories of the seat surfaces X/Y/Z-axis under three conventional driving-speeds were acquired. A special MATLAB program was compiled to calculate the total weighted Root Mean Square (RMS) value by calling the above histories. According to the GB/T 4970-1996, a road test of a passenger car was carried out in the random road surface which equivalent to B level. The car was driven to get the values of total weighted acceleration RMS under three conventional driving-speeds. By comparing the road test result with simulation, the result indicated that the changing trend of total weighted RMS value is consistent as the driving-speed changes, and the ride comfort will decrease when the driving-speed increase. At the same time, it shows that the consistency of the simulation and road test is better.

The multi-body dynamics analysis is an important method to analyze the movement and dynamics characteristics of a car in modern vehicle design process . The twist beam rear suspension which is for rear wheel steering was widely equipped on front engine rear wheel drive vehicles . The modeling of twist beam rear suspensions is always difficult to describe accurately for its unique structural behaviour . First of all , a non-linear method based on multi-body dynamics was used to establish the dynamics model of the twist beam rear suspension system by using the ADAMS/Car . Secondly, the kinematics analysis of the rear suspension was realized and the main suspension parameters (toe angle, camber angle and wheel base) were calculated by changing wheel travel by means of ADAMS/Car . Finally , the suspension was optimized . The result shows that integrative use of ADAMS/Car and ADAMS/Insight in the kinematics analysis and optimized design of the suspensions is rapidly and effectively to design vehicle suspensions .

The arising health problems of ride comfort of passenger cars point out that a lot of effort still has to be put into the design of passive suspension systems.The comfort problem originates from the vibrations transmitted to the driver and passengers caused by the unevenness of the road. This paper reports on an investigation to determine the spring and damper settings that will ensure optimal ride comfort of a passenger car at different speeds. D-optimal designs are developed via multibody dynamics software (ADAMS/Insight) with a model. Evaluation of the comfort improvement was done using an objective function according to the international organisation for standardisation (ISO)2631(1997). The optimised passive suspensions equipped in a passenger car were tested on a test rig in ADAMS/Car. The results show that the vibration levels can be reduced by 47%, generating a drastic comfort improvement.

The engine model with 4 cylinders is built by SolidWorks, the kinematics and dynamics simulations of the engine virtual prototype are done by COSMOSMotion, the results of kinematics simulation are checked, there are very small errors between the simulation results and the calculation results according to formulas. The mainly results of dynamics simulation are given. The simulation result consists with the parameters of the engine.

With the advent of multibody dynamics software (ADAMS) , it has become one of the main simulation techniques to build a multibody system (MBS) in order to evaluate the dynamics performance. The modeling of some component parts such as anti-roll bars and torsion beam rear suspensions is always difficult for the unique structural and non-linear characteristics.A joint force actuator based on multibody dynamics was introduced to represent the component within suspension systems. The kinematics analysis of the torsion beam rear suspension was carried out to validate accuracy and rationality by means of joint force actuators in ADAMS/Car. The result shows that the joint force actuator can be used in the MBS modeling and simulation analysis of non-linear characteristics conveniently.