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This paper presents a new FEA approach for brake squeal simulation, the energy flow analysis. It demonstrates that under certain conditions, two system normal modes with equal or close frequencies may start injecting vibration energy into each other, from dynamic friction mechanism. The vibrations, therefore, can “self-grow” (limited cycle), resulting in system instability, such as brake squeal and brake moan. The theoretical conditions for such positive energy flows to occur are discussed. Test examples and application case studies are presented, along with comparison with, and linkage to, complex eigenvalue analysis.

This paper expands the oral presentation the authors made at 2000 Brake Colloquium [1], and publishes, for the first time, the key concept and procedures of applying an advanced component mode synthesis method, the MacNeal method, in brake squeal simulations. The effectiveness and the efficiency of the overall approach are demonstrated and verified by direct FEA. In addition to squeal propensities and the unstable complex mode shapes, this paper also investigates different mode participation factors (MPF) - Component MPF and System MPF, and component participation factors (CPF). The paper also introduces Acoustic Component Participation Factors (ACPF). Application case studies are presented to demonstrate the commonalities and differences of those factors.