Abstract: Harmonic excitations used in model studies of car suspensions should be treated as far-reaching mathematical simplifications. In actual operating conditions, suspensions are affected by kinematic excitations originating from surface irregularities, known as the transverse micro-profile of the surface. These have the character of random excitations.The article presents the mathematical foundations for describing the aforementioned stochastic excitation and presents a method of data acquisition using a measuring trolley designed and manufactured in the Laboratory of Fundamentals of Measurement Techniques of the Faculty of Transport at the Silesian University of Technology.
A measuring head manufactured in the aforementioned laboratory was mounted on the measuring trolley, enabling the following measurements to be taken: vibration acceleration in the longitudinal, transverse, and vertical directions, rotation angles of the measuring trolley wheel, vehicle speed (measured with high accuracy), and the road surface micro-profile.
Portable computers (laptops) with software, powered by the vehicle’s electrical system, were used for the acquisition of measurement data from road tests.
The suitability of the designed and manufactured measuring heads was verified under road conditions while driving sets consisting of the test car and the towed measuring trolley, which demonstrated the correct operation of the measurement paths and the repeatability of the results.
Verification tests were conducted at various driving speeds up to 50 km/h.
Currently, the measurement system is in the testing phase.
1. INTRODUCTION
In model studies of car suspensions, due to the simplicity of mathematical notation, harmonic kinematic excitations are most often assumed in the equations. This type of excitation does not occur in the actual operating conditions of vehicles. As a result, suspension simulation studies are approximate and do not correspond to actual road conditions.
Transverse road irregularities (profile) are random in nature. A vehicle moving along such a road is excited to vibrate by stochastic excitation. A full description of such processes is difficult. In its description, it is assumed that they are stationary in the wider sense and ergodic. The correctness of such assumptions is confirmed by studies conducted by many research centers. (…)
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Source: Logistyka Magazine