Identification of Pressure-Dependent Modal Properties of Non-Linear Brake Pads by Using Scalable Dirac Impulse
Brake noise or squeal is a major problem experienced by brake system manufacturers, which leads to customer dissatisfaction and the questioning of quality. Research on the NVH performance of brake systems is performed to study and eliminate this problem using advanced testing tools, design modification, dynamometer testing etc. But still it continues to exist. One of the most important reasons is the complexity of the brake pad which leads to non-linear properties. Therefore, it is very important to understand the behavior of the brake pad, in terms of its dynamic characteristics (eigenfrequencies, damping and mode shapes), under varying conditions. Experimental modal analysis is currently used to analyze brake pads for studying these characteristics and is generally performed under free-free boundary conditions. A testing approach under pressure conditions is a step towards reality, as brake pads squeal only during a braking event. Furthermore, the dynamic characteristics of the brake pads are dependent on the pressure and the boundary conditions (location of piston and caliper). Therefore, studying the behavior of brake pads under pressure is a decisive process for solving the squeal issue.
This research includes the development of a test rig to study brake pads under different pressures, analyzing their results and an approach to standardize the testing procedure. The brake pads are excited by a Scalable Automatic Modal Hammer (SAM), with a precise controllable force level. The vibration response is measured by a contactless method using a 3D SLDV.
This research, under these conditions and advanced techniques, results in validated dynamic characteristics of brake pads. This can be used for sensitivity analysis and NVH characterization of brake pads and other automotive components. The conclusions will lead to effective brake pad parameters for a robust brake against squeal research.
KeywordsModal analysis Brake pad Automatic modal hammer 3D SLDV Optical 3D scanning
- 3D SLDV
3 dimensional scanning laser doppler vibrometer
Experimental modal analysis
Frequency response function
Modal assurance criterion
Noise, vibration, harshness
Scalable automatic modal hammer
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