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The development and validation of a brake pad insulator damping measurement procedure by the SAE Brake NVH Standards Committee was presented at the 2010 SAE Brake Colloquium (Paper 2010-01-1685). In Europe, in 2010, the EKB Working Group identified the need to develop a similar procedure, and started some activities which lead to the release of a standard similar but different than the SAE J3001. The SAE and EKB working groups agreed that having a global standard was of paramount importance, so the 2 groups decided to meet in November of 2010 to flush out the details of the J3001 global procedure. The details of the new test procedure, test setup and recommendation for proper test practices are described in this paper. This description provides an excellent foundation for evaluating the insulator damping properties over a range of temperatures and frequencies.

This paper explores the use of geometry of the insulators in attenuating brake squeal. The authors present both simulation and experimental data at component level as well as system level - comparison of brake dynamometer test results of a brake system with and without the geometric tuning of the insulators. Also the authors show the effective usage of the geometry changes to tackle squeal frequencies that are outside of brake pad modal spectrum.

This paper explores some tools used in the prediction of loss factors of a mounted insulator. Resonant test data across temperature and frequency are compared with both analytical and finite element prediction. Modeling and prediction for single-layer and multi-layer; low temperature, high temperature, and multi-temperature range type insulators is verified, and the limitations due to inherent variability of material properties are discussed. A beam representation is compared with an insulator-mounted brake pad in the identification of critical design factors that affect the composite loss factor. A significant issue in effectiveness of an insulator as a damper is its bonding with the backing plate, which is estimated using finite element analysis and testing. Finally the results of a DOE study exploring the benefits of selective de-bonding are presented.

Brake insulators often offer optimal solutions to squeal noise. In the process of engineering solutions to reduce the brake noise, a system-level finite element complex eigenvalue analysis is often used and has gained popularity in recent years. Models of insulators have also been proposed for system-level evaluation, however many challenges remain in efficiently implementing an insulator model, owing to complexities of the insulator component model. The complexities arise from the visco-elastic behavior (primarily the frequency and temperature dependence), and the thin polymer/steel multi-layer nature of the construction - typical in an insulator. As a first part of a joint investigation, this paper explores the nature of frequency and temperature dependence in insulator models and reduces the cumbersome multi-layer model into a simpler form that can be more easily implemented in a typical brake system stability analysis.