Stiffness Synthesis of a Five-Rod Suspension for Given Load-Displacement Characteristics

Abstract

The paper describes a novel algorithm for solving the synthesis problem of a multi-link wheel-guiding mechanism with a known topology and dimension. The synthesis objectives contain the elastokinematical specifications, described by a set of spatial displacements that the wheel carrier should undergo from a design position under specified loads corresponding to typical car manoeuvres. Radial spring rates of cylindrical elastomeric bushings, embodied in the suspension rods, are considered as design variables. Relations between the design variables and the objectives are established using the first-order kinematics and screw calculus, under assumptions about small displacements and linear force-deflection characteristics of the flexible elements. The problem is solved by using a constrained linear least-squares algorithm. Depending whether the input data is provided by a designer or acquired during suitable experiments, the algorithm can be used for synthesis or estimation of the stiffness parameters. Numerical examples are solved for two five-rod suspensions, with the same topology but different configuration and dimension, installed at rear-driven axles of actual cars. Static spring rates of the five rod-bushings are determined, for which both suspensions satisfy the formulated ride/handling criteria in the best way. Fundamental characteristics and limitations of the suspensions are described.

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

“…Recommended ranges [8,11] of selected components of the wheel carrier displacement (d), produced by an external load change (w) at the wheel centre corresponding to some typical car maneuvers are contained in Tab. 1.…”

“…More links means more design freedom, but at the expense of need to use of more complicated computational approaches. Five-rod (also known as five-link or five-point) suspension mechanism of the car wheels can be considered as an example of an in-parallel mechanism, like Stewart platform [7,8]. Other structures of the independent wheel suspensions (e.g.…”

“…Fewer known papers are devoted to dynamic analysis [3,10]. Problem of multi-link suspension synthesis is very rare in available literature [6,8].…”

“…Five stiffness coefficients of elastomeric bushings installed in joints of the suspension rods are considered as design variables. The design objectives contain the so-called elastokinematical specifications, what was considered by the authors already [8], but a defined dynamic criterion, concerning the so-called rolling comfort, is now taken into account additionally. Two models, i.e.…”

Optimization of kinematic parameters of JCK manipulator

“…Do tego celu sformułowano w środowisku Matlab [6] model kinetostatyczny manipulatora JCK, opisujący właściwości kinematyczne i statyczne mechanizmu. Zadanie optymalizacji wielokryterialnej z ograniczeniami rozwiązano wykorzystując algorytmy genetyczne [2,3,4].…”