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The propensity of brake squeal depends significantly on the vibrational characteristics of disc rotors. In this study, we focused on the differential effects of disc dimensions on the natural frequencies of various vibration modes. We analyzed the results of the CAE factorial experiments presented in our previous paper, which were conducted on four disc rotors with different designs such as front-and back-vented and solid discs. As a result, the effects of disc dimensions on natural frequencies were confirmed to depend on vibration modes, their orders (or the number of nodal diameters), and the basic design of disc rotors. The dimensions that change the stiffness of the friction ring such as ventilation-path width and fin thickness had larger effects on the out-of-plane circumferential modes of high orders than those of low orders. The dimensions around the necking, on the other hand, had a large effect on the low-order modes.

We describe our practical procedure of designing thermally robust brake discs using conventional CAE. First, we review the literature describing brake judder, measurement technologies, and CAE focusing on brake discs. Second, we present some experimental results confirming what effect the basic configurations of brake discs have on thermal behaviors and the correlation between CAE simulation and physical test results. Finally, we propose a design strategy for developing thermally stable brake discs with an outer-hat configuration. We carried out a series of CAE experiments based on the Taguchi Method and determined the critical parameters for reducing the amount of coning. We also present some simplified models using classical theory regarding the strength of materials to discuss what effect the dimensional parameters have on the discs' thermal deformation.

Brake squeal is a critical issue for automotive brake systems and its propensity significantly depends on the natural frequencies of brake discs. The variation in natural frequencies is caused by various factors in the disc manufacturing process, from foundry through machining. To reduce this variation, we analyzed the factorial effects of material and dimensional properties on natural frequencies of brake discs with various configurations by conducting intensive computer-aided engineering experiments. These experiments were performed accurately and quickly with the help of our original brake disc design system. As a result, we determined the critical factors affecting the natural frequencies of brake discs and their contribution.

We have constructed an original brake disc design system by standardizing, automating, and speeding up each design process. This system consists of two steps. In the first step, a designer, without professional knowledge or skills regarding CAE, can easily carry out FEA by manipulating pull-down menus, parametric design, and automated modeling and meshing. Further, our new computer program automatically identifies each eigenmode. It takes less than two hours for a complete FEA of a new design. In the second step, the developed postprocessor makes it easier and faster to compare the simulated results of many design alternatives and determine the optimum solution. Through the accumulation of vast numbers of FEA cases and tests for validation, we have obtained the knowledge of the effects of disc configurations, dimensions, and material properties on resonant frequencies and thermal deflections.