Transient non-linear dynamic analysis of automotive disc brake squeal – On the need to consider both stability and non-linear analysis

Chaos in brake squeal noise

An approximate analysis method for brake squeal is presented. Using MSC/NASTRAN, a geometric nonlinear solution is run using a friction stiffness matrix to model the contact between the pad and rotor. The friction coefficient can be pressure dependent. Next, linearised complex modes are found where the interface is set in a slip condition. Since the entire interface is set sliding, it produces the maximum friction work possible during the vibration. It is a conservative measure for stability evaluation. An averaged friction coefficient is measured and used during squeal. Dynamically unstable modes are found during squeal. They are due to friction coupling of neighbouring modes. When these modes are decoupled, they are stabilised and squeal is eliminated. Good correlation with experimental results is shown. It will be shown that the complex modes base-line solution is insensitive to the type of variations in pressure and velocity that occur in a test schedule. This is due to the conservative nature of the approximation. Convective mass effects have not been included.

Brake saueal analysis by finite elements

Wear prediction of friction material and brake squeal using the finite element method

A new treatment for predicting the self-excited vibrations of nonlinear systems with frictional interfaces: The Constrained Harmonic Balance Method, with application to disc brake squeal

There are typically two different methodologies that can be used to predict squeal in a disc brake, i.e., complex eigenvalue analysis and dynamic transient analysis. The positive real parts of complex eigenvalues indicate the degree of instability of the disc brake and are thought to associate with squeal occurrence or noise intensity. On the other hand, instability in the disc brake can be identified as an initially divergent vibration response using transient analysis. From the literature it appears that the two approaches were performed separately, and their correlation was not much investigated. In addition, there is more than one way of dealing the frictional contact in a disc brake. This paper explores a proper way of conducting both types of analyses and investigates the correlation between them for a large degree-of-freedom disc brake model. A detailed three-dimensional finite element model of a real disc brake is developed. Three different contact regimes are examined in order to assess the best correlation between the two methodologies.

Complex eigenvalue analysis and dynamic transient analysis in predicting disc brake squeal

This paper studies car disc brake squeal by transient analysis and details the first attempt to combine heat conduction analysis, contact analysis and transient analysis of disc brake squeal. The contact pressure at the disc/pads interface is first computed, and the information is used to define friction-induced heat flux. Its resultant heat conduction is then analysed. Finally, transient analysis is performed, considering the influence on squeal generation of contact pressure distribution affected by brake pad surface roughness and thermal deformation. A noticeable difference is found between the dynamic responses obtained with the thermal effect from those without the thermal effect.

A combined analysis of heat conduction, contact pressure and transient vibration of a disk brake

This paper presents a methodology for predicting disk brake squeal using the Finite Element (FE) method whereby a three-dimensional FE model of a real disk brake is validated at the component and assembly levels, and more importantly through contact analysis. Consideration of real surface topography of the friction material in the contact interface model represents a major advancement. Kinetic friction coefficients are determined from squeal tests. Two different friction characteristics with friction damping are simulated. The predicted results show that the refined contact interface model can improve accuracy of prediction and also reduce the number of redundant unstable frequencies.

A prediction methodology of disk brake squeal using complex eigenvalue analysis

This paper presents an approach to predict automotive windscreen wiper chatter noise using the finite element method. In this study, a 3-dimensional finite element model of a real wiper blade is developed and then validated using experimental modal analysis. In order to assess stability of the wiper blade assembly, complex eigenvalue analysis is performed using ABAQUS. The positive real parts of a complex eigenvalue indicate an unstable system. The baseline model is first simulated and stability of the system is examined. Having found a predicted unstable frequency that generates chatter noise, various structural modifications are proposed in order to reduce the vibration.

Abd Rahim AbuBakar

Papers

Complex eigenvalue analysis and dynamic transient analysis in predicting disc brake squeal

Wear prediction of friction material and brake squeal using the finite element method

A combined analysis of heat conduction, contact pressure and transient vibration of a disk brake

A prediction methodology of disk brake squeal using complex eigenvalue analysis

Complex Eigenvalue Analysis of Windscreen Wiper Chatter Noise and its Suppression by Structural Modifications