Optimization of 5-rod Car Suspension for Elastokinematic and Dynamic Characteristics

Abstract

The paper presents optimization of 5-rod (5-link) suspension mechanism used in passenger cars for independent guiding of the wheels. Selected stiffness coefficients defined for five elastomeric bushings installed in joints of the suspension rods are considered as design variables. Two models with lumped parameters (i.e. elastokinematic and dynamic) of wheel-suspension-car body system are formulated to describe relationships between the design variables and the performance indexes including car active safety and ride comfort, respectively. The multi-criteria goal function is minimized using a deterministic algorithm. The suspension with optimized bushings rates fulfils desired elastokinematic criteria together with a defined dynamic criterion, describing the so-called rolling comfort. An event of car passing over short road bump is considered as dynamic conditions. The numerical example deals with an actual middle-class passenger car with 5-rod suspension at the front driven axle. Estimation of the models parameters and their verification were carried out on the basis of indoor and outdoor experiments. The proposed optimization procedure can be used to improve the suspension design or development cycle.

Archive of Mechanical Engineering

“…A few conventions of this approach are known [9]. Roll-pitch-yaw convention is used usually in vehicle dynamics for vehicle body orientation [3], [4], [7].…”

A Method for Finding the Static Equilibrium of the Non-Steered Wheel Suspension Systems Used in Passenger Cars

“…Establishing this position is necessary to assess the behavior of the vehicle in various operating/loading regimes, and to determine the reactions in joints in order to properly size them. Such a problem is approached in the literature mainly using energetic methods, based on the minimum energy potential in the equilibrium position, or by kinetostatic analysis methods, decomposing the suspension mechanism into components and expressing their equilibrium equations [9][10][11][12][13][14][15][16]. The equilibrium position can also be determined by using automatic analysis algorithms, which are integrated in the commercial MBS (Multi-Body Systems) software environments, such as ADAMS, DYMES, or SIMPACK.…”

“…Determining the equilibrium position is further reduced to a mono-objective optimal design problem (without design constraints), which consists of determining the values of the independent design variables Z Gs and Z Gd , for which the function: (14) has a minimum value. The solution can be determined through an iterative process by considering discrete values for the two design variables in the compression (up)-extension (down) operating range of the suspension mechanism, and by identifying the values that ensure the minimum of the function (14).…”

Method for the quasi-static analysis of beam axle suspension systems used for road vehicles

“…A complex elastokinematic model was developed for the optimal design of a five-rod car suspension in terms of car active safety and ride comfort. 22 The elastokinematic analysis of a rectilinear rear independent suspension model was approached in Liu et al 23 by using the transfer matrix method. In this case, the statics equation was obtained by introducing external loads and expanding the overall system transfer equation, and different configurations of bushings were discussed with respect to the natural frequency and static deflections.…”