Road Tests Adopted to Analyse Cars’ Vibrational Behaviour 2001-01-1098
Optimization of ride comfort is becoming increasingly important in chassis development. Constantly rising traffic density and comfort-orientated customer preferences are mainly responsible for this. Comfort and its improvement are important, not only on bad road surfaces, but also on even surfaces.
The complexity of analysis leads to a strong link between car testing and simulation. The testing itself is divided in to roadtests and test stands.
It is of outstanding importance to analyze the vehicles vibrational behavior from road tests as it is a real life situation. In order to get meaningful results from the roadtest the vehicle has to be seen as a complete vibrational system. The vibrational behavior of a system is clearly defined by input and output of the system. Road tests are chosen in relation to the predicted car. The roads surface is the input of the system exciting the vibrational subsystems of a car.
The ride tests are used for the evaluation of drive response behavior. They are complemented by subjective assessment. Open loop tests were carried out for the evaluation of ride comfort. For a comprehensive evaluation of ride comfort, the most widely different forms of excitation are necessary. The vehicle is stimulated fundamentally by deterministic and non-deterministic, road-generated signals. In addition to system-theoretical considerations, practical experiences from the ride test are also considered. This is necessary to discover which excitation form will provide the most comprehensive description of the vibrational behavior of the system.
The analysis procedures used are: Time and frequency range representation, running mode analysis in time and frequency domain and modal analysis. Its the combination of those methods together with the engineers experience, which leads to the results of the measurement to a meaningful analysis.
How to use mentioned tools will be shown with a focus on practical work and some animations.