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Motivated by a combination of increasing consumer demand for fuel efficient vehicles, more stringent greenhouse gas, and anticipated future Corporate Average Fuel Economy (CAFE) standards, automotive manufacturers are working to innovate in all areas of vehicle design to improve fuel efficiency. In addition to improving aerodynamics, enhancing internal combustion engines and transmission technologies, and developing alternative fuel vehicles, reducing vehicle weight by using lighter materials and/or higher strength materials has been identified as one of the strategies in future vehicle development. Weight reduction in vehicle components, subsystems and systems not only reduces the energy needed to overcome inertia forces but also triggers additional mass reduction elsewhere and enables mass reduction in full vehicle levels.

Brake related warranty costs are a major concern to the automotive industry. Large part of these costs are due to noise, more particularly due to the brake squeal complaints. Computer-aided engineering solutions have attracted a lot of attention from the engineering and development community for more effective brake product development. Recently, three brake squeal analysis methods were implemented on disc type brakes in a vehicle program at Ford. This paper summarizes the results and documents the experience obtained during implementation in the vehicle CAE process.

To reduce warranty cost due to brake squeal and provide guidance for brake design, it is important to understand the contributions of key brake design parameters to brake noise. In this paper, a new technique, which employs the nonlinear transient finite element method as well as Taguchi method, is proposed as a design tool for improving the quality of brake systems. This DOE technique has been implemented to a car program. The final results identified the major parameters associated with the brake noise and also led to an optimal design by selecting appropriate levels of those parameters.

A nonlinear transient finite element method was developed to analyze brake squeal occurrence. It overcomes the drawbacks associated with the conventional methods such as modal analysis and complex eigenvalue analysis. It includes the prediction of contact surface variation during the braking process and the complex friction phenomena at rotor-pad interfaces. A new solid element was also developed to suit the brake squeal analysis. A fast Fourier transformation (FFT) was employed to convert the results in the time domain generated from nonlinear transient analysis into the frequency domain to identify the frequencies associated with noise. Good correlation, between the squeal frequencies predicted by the proposed method and those obtained from tests, has been established.

An eight-noded hexahedral element is developed for linear and nonlinear analyses, which can be also used to analyze bending and sheet metal forming problems. The development is based on the formulation of multiple-point quadrature elements proposed by Liu, Hu and Belytschko [1]. In this new element, one-point quadrature, instead of four-point or eight-point quadrature, is used so that computational time is substantially reduced without adversely effecting the accuracy. Hourglass control is included in the element formulation to suppress spurious modes. The volumetric locking for nearly-incompressible material, as well as the shear locking in bending problems are also eliminated. Several examples are presented to demonstrate the performance of this element.

A new method to predict brake squeal occurrence was developed by MSC under contract to Ford Motor Company. The results indicate that the stability characteristics of this disc brake assembly are governed mainly by the frictional properties between the pads and rotor. The stability is achieved when the friction coefficient of the pads is decreasing as the contact force increases. Based on the results, a stable brake system can be obtained without changing the brake structure by incorporating the appropriate frictional coefficient in the brake system. The method developed here can be also used as a tool to test the quality of any brake design in the early design stage.