About improving the stand testing of the suspension

Abstract

Various methods are used to determine the technical condition of the vehicle suspension. In Europe, stands based on the EuSAMA method are most widely used. In the classic version, this method, the output parameter of which is the "adhesion coefficient", characterizes traffic safety to a greater extent. But for technical workers of the car service, the damper device is more interesting in the suspension as the most complex component in the suspension, the condition of which cannot be assessed visually. In addition, the classic EuSAMA has a number of disadvantages - method errors that affect the accuracy of the diagnostic result. Efforts are being made to improve the method in order to increase the possibility of diagnosing shock absorbers and reduce the influence of extraneous factors. A promising method in this context can be called the method based on the use of phase relationships, namely, on measuring the phase difference (phase angle) between the phase of the platform oscillation and the phase of the dynamic force oscillation in contact with the tire platform. This paper presents the results of modeling the suspension of the unsprung part (suspension quarter) with different damping of the shock absorber. Modeling was performed in the time domain. For one set of suspension parameters, the phase frequency response was obtained, the phase angle dependencies and EuSAMA coefficients were obtained for different damping of the shock absorber, as well as estimates of the influence of stiffness, tire damping, stiffness of the elastic element of the suspension, the value of the unsprung mass on the value of the phase angle.

Keywords: suspension diagnostics, EuSAMA, shock absorber, modeling, phase angle.