Abstract
Last years, requirements to improve the behaviour in terms of noise perception inside vehicles are rising to get a better comfort. Exterior noises perceived inside the vehicle (engine, aerodynamics, rolling, etc) have been reduced so that perception of the interior noise sources has increased at the same time. In this category, annoying noises like squeak and rattle noises coming from poor fitting between parts or even wearing out are creating an increasing feeling of lack of comfort and poor perceived quality for the final customer.
This is the reason why no NVH (Noise, Vibration & Harshness) study might be successful without including squeak and rattle noises considerations in order to prevent them from happening even since the first stages of design and development cycle for the vehicle. Extensive investigations have been made at CIDAUT about this subject, mainly through the feature known as stick-slip, phenomenon closely related to the appearance of squeak noises between different parts of the vehicle.
The scope of this work is not only to identify the triggers of this type of annoying noise but also to set up the material properties related with these phenomena so that all of this information could be taken into account during the design and development phases of the vehicle.
Experimental phase of this study has been based on the design and construction of a test and trial equipment that allows the comparison with the empiric models. As an example, many studies have been conduced analyzing friction between parts with different geometries and materials, controlling and tracking outputs as displacement, speed and acceleration, loads and sound pressure,... building up tables and graphics that allow us to set up conclusions on the appearance of these phenomena. These conclusions will let us avoid and minimize the effect of stick-slip in squeak events.
This paper summarizes trials made on the test equipment that allows us to analyze problems related with the stick-slip in a controlled environment and draw conclusions based on the characterization of different material properties that have influence on this squeak phenomenon.
Keywords: Squeak, stick-slip, friction, contact, NVH