Browsing Engineering and Informatics by Subject "Brakes"
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Brake system simulation to predict brake pedal feel in a passenger car.Braking system characteristics, brake system performance and brake system component design parameters that influence brake pedal `feel¿ in a passenger car have been studied using the simulation modelling package AMESim, in particular to model the linear and nonlinear characteristics of internal components. A passenger car hydraulic brake system simulation model incorporating the brake pedal, booster, master cylinder, brake lines and calipers has been developed to predict brake system response to assist in the design of braking systems with the desired brake pedal force / travel characteristic characteristics to create good brake pedal `feel¿. This has highlighted the importance of system components, in particular the master cylinder and caliper seal deformation, and the operating characteristics of the booster in determining the brake pedal force / travel characteristic. The potential contribution of these 3 components to brake pedal `feel¿ improvement has been investigated, and the results of the AMESim model have been verified using experimental measurement data. The model can be used in the future to provide an accurate prediction of brake system response at the design stage thereby saving time and cost.
Investigation of stick-slip vibration in a commercial vehicle brake assemblyThere are several types of disc brake instabilities associated with the brake systems; however, they are usually classified into two main categories depending on the frequency range: brake groan 0–300 Hz and brake squeal 1– 16 kHz. The groan is associated with the stick-slip motion while the squeal is associated with the modal coupling. This paper presents a detailed analysis of low frequency noise (0–300 Hz) in a commercial vehicle trailer disc brake as a result of stick-slip vibration. A range of experimental techniques are used to understand the characteristic behaviour of the caliper and the brake pads during braking events on a laboratory test rig. The analysed brake system comprised a full disc brake assembly and the trailer suspension system with a beam axle. Laser-based optical displacement sensors were used to investigate the deformation of the caliper body and the brake pads during a braking application. The contact pressure distribution at the disc/pad interfaces were also measured to gain more insight into the contact profile of the pad surfaces. Results revealed that the stick-slip phenomenon, in this study, was a result of the combination of the deformation of the caliper and the friction material formulation of the brake pads. In addition, it was observed through the testing of two different sets of pads that a low compression modulus would help to reduce the stick-slip phenomenon.