Simulation assessment of the impact of inertia of the vibration plate of a diagnostic suspension tester on results of the EUSAMA test of shock absorbers mounted in a vehicle

摘要

As mentioned in the title, the paper presents an assessment of the impact of inertia of the vibration plate of a diagnostic suspension tester on results of the EUSAMA test of the condition of shock absorbers mounted in a vehicle. In the method adopted by EUSAMA, the normal force between the vehicle tyre and the vibration plate is measured during the tests. The percentage ratio of the minimum value of this force to its static value, within the excitation frequency range of 0-25 Hz, is the "EUSAMA indicator". It is taken as a basis for diagnostic assessment of the condition of the shock absorbers mounted in a vehicle. In the measuring systems of the testers, the force between the tyre and the vibration plate is measured indirectly at the point where the excitation is applied to the plate on which the wheel of the suspension system under test is placed. This means that the force measured includes not only the normal tyre-plate contact force but also the force of inertia of the plate. The authors made a simulation analysis of the impact of the inertia of suspension tester's vibration plate on the EUSAMA test results. The simulations were carried out both in the frequency and time domain. In the latter case, the EUSAMA test conditions, i.e. the excitation frequency varying in time, were replicated. The results reveal that the vibration plate inertia may considerably distort results of the EUSAMA test. For this inertia to be taken into account, the tester must be enabled to measure the vertical acceleration of the vibration plate.