No description available.

No description available.

Not available / text

No description available.

No description available.

In recent years automobile safety has become more and more important.The braking device contributes largely to the problem of safe driving.

Submitted in fulfillment of the requirements for the degree of Master in Engineering: Mechanical Engineering, Durban University of Technology, Durban, South Africa, 2017. / Despite the huge improvements made in the development of vehicle brake pad materials, problems such long stopping distances, noise pollution, and heat dissipation still continue to persist. In this regard, a novel polymer-based hybrid nanocomposite brake pad (HC) has been developed. Here, a combination of carbon-based materials, including those at a nanoscale, was used to produce the brake pad. The coefficient of friction, wear rate, noise level, and interfacial temperature was investigated and compared with that of a commercial brake pad material (CR). It was found that the brake pad performance varied with the formulation of each pad. Hybrid nanocomposite brake pads material exhibited superior performance in most tests when compared to the commercial brake pad. They exhibited a 65% lower wear rate, 55% lower noise level, 90% shorter stopping distance, and 71 % lower interfacial temperature than the commercial brake pad (CR). Furthermore, mechanical properties such as hardness, compressive strength, shear strength, and impact resistance were also evaluated. The material exhibited a 376% higher shear strength, 100% improved compressive strength, 77% greater modulus and 100% higher impact strength than the commercial brake pad. The hardness of both brake pads material was statistically comparable. Additionally, the thermal stability, degradation, water and oil absorption behaviour were measured. It was found that HC brake pad material exhibited a 100% lower water absorption and 80% oil absorption rate. The brake pads also exhibited a thermal stability within the brake pad standard maximum working temperature of 300 -400 0C. The superior performance of hybrid nanocomposite brake pad material observed was due to synergism between the carbon-carbon additives and uniform dispersion of carbon fiber as shown in Figure 4.16. Scanning electron microscopy study was subsequently performed on fracture and worn surfaces of the brake pads. The micrographs show changes in the structural formation after the incorporation of carbon based fillers. It also shows the smooth structure and uniform dispersion of the carbon fiber. The smooth surface of the worn brake pad is an indicative of a harder structure. No ploughing or score marks were evident. Hence, it was deduced that the reinforced had superior mechanical and tribological properties. These improved properties are suggestive of materials that may be successfully used for brake pad application. / M

The heat dissipation and thermal performance of ventilated brake discs strongly depends on the aerodynamic characteristics of the air flow through the rotor passages. In this thesis, the thermal convection is analyzed using an analytical method, and the velocity distribution, temperature contours and Nusselt number are determined. Then numerical models for different rotors, pillar post rotors and vane rotors are generated and numerical simulations are conducted to determine the desired parameters. To analyze more realistic vane and pillar post rotor models, commercial CFD software packages, Fluent and Gambit, are used to simulate the heat flux rate, air flow rate, velocity distributions, temperature contours, and pressure distributions inside the rotors. Furthermore, sensitivity studies have been performed, to determine the effects of a different number of vanes or pillar posts, inner and outer radii and various angles of vanes. To automate the tedious and repetitive design process of the disc rotor, a design synthesis framework, iSIGHT, is used to integrate the geometrical modeling using GAMBIT and numerical simulations based on FLUENT. Through this integrated design synthesis process, the disc rotor geometrical optimization is performed using design of experiment studies. / UOIT

The creative project is an educational film that will be used in vocational auto mechanics classes as an aid to the lecture and demonstration of brake repair.Eight millimeter Kodak color film was used and is supplemented with magnetic taped sound.The film deals with the steps and procedures that are necessary to complete a brake repair job. Each step explains the procedures and outlines the technical knowledge needed to complete the brake repair job.

Friction-induced oscillations occur in many engineering systems, often resulting in noise, vibration, and excessive or uneven wear. This research addresses the suppression of such oscillations, especially with application to braking systems, through the use of high-frequency dither signals. Brake squeal is an annoying and elusive problem too often present in braking systems of automobiles, trucks and aircraft. In previous work, the effectiveness of high-frequency dither to eliminate squeal in an automotive disc brake assembly was demonstrated experimentally. The main features of the dither-squeal cancellation system was the application of a high frequency variation in the brake pressure force accomplished by means of a piezoelectric stack placed behind one of the brake pads. This thesis contains a theoretical and numerical treatment of the application of dither to frictional systems. Two types of systems are investigated. The first is a classic, mass-on-a-moving belt problem, which experiences friction-induced oscillations similar to those encountered in brake applications. The system is first studied using an analytical technique based on the method of averaging. It is shown that, depending on the system, friction, dither-waveform, and belt-speed parameters, dither can stabilize an unstable system. However, in some cases, dither can destabilize an initially stable system. These results are verified numerically using time integration. The second type of system analyzed in this thesis is an annular plate with a rotating frictional device. The method of multiple scales is used to predict subcritical regions of instability; the results are validated using Floquet theory. The thesis treats both tangential and normal dither, the latter being closer to the brake application. It is found that normal dither, in addition to being harder to analyze, is much less effective than tangential dither.