Controlling the Vehicle Disc Brake Squeal Using A 10 DOF Model

Ibrahim Ahmed¹ and Yasser Fatouh²

¹Department of Automotive Technology, Faculty of Industrial Education, Helwan University, Cairo, Egypt.

*Corresponding author Email: ilmahmed1968@yahoo.co.uk

Accepted 20 December 2012

Abstract

The disc brake squeal generated during the duty of the brake is considered as a highly main source of discomfort for passengers.  It is also considered to be a high frequency noise when it is bigger than 1 kHz audible vibration of braking components which is a significant problem that has not been solved satisfactorily until recently. Squeal noise is strongly correlated to the squeal index and degree of instability of the brake system assembly. Decreasing or controlling this squeal noise to some extent during braking is very important matter for the comfort of passengers.  So, a mathematical prediction model of 10-degree-of-freedom has been developed to study the effect of different brake components parameters on the degree of instability and squeal index of the brake system.  The model has considered such factors as the distance between clamping bolts of the caliper and width of the friction material, which were not fully covered previously besides some other factors.  In this paper, the system is considered to be completely state controllable and hence it will be “observable”, then poles of the closed-loop system will be placed at a desired location by means of state feedback through the state feedback gain matrix.    This term of observability is found to be important because, in practice, the difficulty encountered with state feedback control is that some of the state variables are not accessible for direct measurement, with the result that it becomes necessary to estimate the immeasurable state variable in order to construct the control signals.  Complex eigenvalue analysis and state-space representation of the model have been solved using a MATLAB program.  It is evident from the analysis that Young’s moduli of the rotor and friction material have a great effect on the occurrence of squeal.  The harder the friction material the bias of the brake to squeal.   It is shown also that the squeal noise of the brake decreases with increasing semi-distance between the clamping bolts of the caliper to be at optimum value between 50-70 mm.  The results have show that the predicted squeal tendency at varying all the studies parameters with feedback control signal is as less as possible to be 43 % compared to other single parameters without feedback signal.   

Keywords: Ventilated disc brake, brake, squeal, SI, degree of instability, eigen frequency, controllable and observable.