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The direct finite element analysis (FEA) approach for disc brake squeal prediction is presented in this paper. A linear model is developed to include the impact of negative μ-v slope on brake systems noise performance. The recently-developed iterative algorithm - ABLE, is used to solve the resulting large-scale complex eigenvalue problems on a PC. Efficiency and effectiveness of the algorithm are discussed. Good correlations are achieved between simulation and measurement, both in squeal frequencies and corresponding unstable modal shapes. Initial study has also validated the conventional wisdom that negative μ-v slope can cause more system instabilities.

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.

Brake noise has been a problem since the early days of motoring, and a lot of studies have been made, - from the energy source of brake squeal [ 1… 3] to the vibration modes in squealing [ 4…5] to the geometric coupling characteristic [ 6… 10]. These were discussed mostly based on bending vibration of brake components. However, a new cause of the noise was found in the longitudinal vibration of the disc rotor. According to our investigation, the occurrence of the noise has been increasing in the market. Fundamental studies and experiments were conducted. The existence of the longitudinal vibration noise was confirmed, and effective preventive measures were demonstrated.