Abstract
In presence of squeal, Operational Deflection Shapes (ODS) are classically measured to gain understanding of brake behavior. A simple numeric example is used to justify the use of time-frequency analysis and expectation two real shapes should dominate the response. Using measurements on a real brake, this expectation is shown to hold even in the presence of variations with wheel position as well as reproducibility tests. For a proper relation with the model, it is desirable to also extract modes. The test campaign is used to illustrate how this can be quite difficult due to reproducibility problems. Finally, shapes characterizing the squeal event are fundamentally limited by measurable quantities. Minimum Dynamic Residual Expansion (MDRE), which estimates test motion at all FE degree of freedom, is shown to be applicable for industrial models and give insight test and model imperfections.
KEYWORDS Operational Deflection Shapes, limit cycle, shape expansion