About the question of selection of the type of vibrostand for diagnostics of vehicle suspension
Abstract
Determining the technical condition of the suspension, diagnosing shock absorbers can be considered as a classic task of identifying the parameters of an oscillatory system. To solve this problem, a procedure using input test signals in the form of a pulse, a step signal or a harmonic signal of different frequencies is usually used. All these possibilities have been used in various periods of time, however, at present, for a number of reasons, car service equipment manufacturers prefer stands with a test harmonic signal. Two types of such stands are produced. The first of them, based on the principle of resonance excitation, is called resonant. The second type, which is based on the high-frequency resonance of the sprigless part of the wheel, is called the EuSAMA method. The principles of construction, features of work, diagnostic parameters of stands are widely covered in the literature. The use of resonance phenomena, the use of test harmonic signals, the identical appearance of the stands largely mislead the users of the stands and do not contribute to a competent and informed purchase. This work is devoted to a comparative analysis of some of the main characteristics of the stands and the conclusions of the work may be useful to car service technologists when choosing equipment. Based on considerations of the labor intensity of preparatory operations during full-scale tests, an analytical approach is adopted in this study. Of the two types of stands, the stand based on the resonant principle is more complex. Its block diagram contains three masses, three elastic devices and two damping devices. In this work, a system of three equations of force interaction and a computer model in the Matlab/Simulink environment is compiled. As a result of the simulation, comparative characteristics of sensitivity and error were obtained for different internal pressure of the wheel of the representatives of the "resonant" and EuSAMA stands.
Keywords: resonant vibration stands, eusama, modeling, comparative characteristics of sensitivity, errors.
