Abd Rahim AbuBakar

Complex eigenvalue analysis and dynamic transient analysis in predicting 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.

A prediction methodology of disk brake squeal using complex eigenvalue analysis

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

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.

Stability Analysis of a Linear Friction-Induced Vibration Model and Its Prevention Using Active Force Control

This paper presents friction-induced vibration (FIV) caused by combined mode-coupling and negative damping effects in a simple FIV model. In doing so, a new four-degree-of-freedom linear model which consists of a slider and a block is proposed and then simulated using MATLAB/Simulink. Stability or instability of the FIV model is defined by the convergence or divergence of time domain responses of the slider and the block. Having found critical slope of friction-velocity characteristics that generate instabilities in the model, a conventional closed loop proportional-integral-derivative (PID) controller is first introduced into the main model in order to attenuate the vibration level and subsequently to suppress it. Later, the model is integrated with the active force control (AFC) element to effectively reject the disturbance and reduce the vibrations. It is found that the integrated PID-AFC scheme is effective in reducing vibration compared to the pure PID controller alone. Thus, the proposed control scheme can be one of the potential solutions to suppress vibration in a friction-induced vibration system.

Suppression of drum brake squeal through structural modifications using finite element method

Reducing squeal from brakes system has become a challenging task for brake engineers. To date, a large number of proposals have been implemented in tackling disk brake squeal but very few solutions have been forwarded in drum brake assembly. This paper attempts to propose a solution to reduce drum brake squeal through structural modifications by using the Finite Element (FE) method. A three-dimensional FE model of an actual drum brake system is developed and validated. First, the baseline FE model is simulated to predict squeal and then several structural modifications are proposed. Finally, dynamic transient analysis is performed for selected modified models in order to confirm predicted results obtained from complex eigenvalue analysis.

A robust active control method to reduce brake noise

In this paper, a novel approach to suppress vibration that causes brake noise is proposed employing a closed-loop feedback control method using an Active Force Control (AFC) based strategy. It is used in conjunction with the classic proportional-integral-derivative (PID) scheme that is typically incorporated in the outermost positional control loop. The idea is to introduce an active element that dynamically compensates the disturbances through a control mechanism that takes into account the direct measurements and estimation of parameters in the AFC section. A disc brake model is considered and simulated taking into account a number of operating and loading conditions. Results clearly show the superiority of the proposed AFC-based scheme compared to the pure PID counterpart in suppressing the vibration and hence the brake noise.

Numerical Analysis of Car Disc Brake Squeal Considering Thermal Effects

Friction-induced vibration and noise emanating from car disc brakes is a source of considerable discomfort and leads to customer dissatisfaction. The high frequency noise above 1 kHz, known as squeal, is most annoying and is very difficult to eliminate. It was recently estimated that noise, harshness and vibration (together known as the NVH problem), including disc brake squeal, generated warranty cost of about US

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

1 billion a year to the automotive industry in North America alone.