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Frequency Sweep Excitation Test Track

Published: 12 May 2011

The behaviour of a vehicle and its parts changes with temperature. The effect of temperature will alter the dynamic behaviour of the car and also affect the acoustic properties. For example, squeak and rattle noise are more pronounced in cold climate. In cooperation between Arctic Falls, Colmis, IceMakers, CASTT and Luleå University of Technology a Frequency Sweep Excitation Test Track has been developed. The track enables a systematic test procedure. The project aims to further develop the test track using vehicle dynamic modelling and simulation, and field measurements.

A vehicle travelling along the Frequency Sweep Excitation Test Track with a constant speed will be exposed to a constant force with a changing frequency. The force is created from obstacles mounted on the test track and the excitation frequency increases (or decreases) as the distance between the obstacles varies along the track. Because the frequency varies in a controlled manner, various noise sources inside the car can be investigated in a systematic way with better repeatability. As compared to using a wooden step track that only excites one frequency at a time or a cobblestone track that causes a randomly varying force. Using the Frequency Sweep Excitation Test Track one can quickly detect, locate and identify squeak and rattling noise, natural frequencies, and weaknesses, making it an important complement to wooden step tracks, cobblestone tracks and twist hills.

In the project different design parameters of the test track, such as obstacle shape, are studied using mathematical models of the tire and the suspension. The model is validated by a comparison with field measurements using different build prototypes. The research aims to increase the level of knowledge in the field of vehicle dynamics and noise, vibration and harshness (NVH) in cold climate.