Analysis of a new squeak test apparatus developed for objective rating of squeak propensity and building a database to minimize squeak problems in automotive engineering

摘要

A test apparatus to quantify squeak propensity of given materials pairs was designed. The device employed a sprag-slip mechanism to induce an unstable, self-exited sliding motion in a consistent and repeatable manner. An analytical model of the system was developed to study dynamics of the system and design the apparatus. Stability analysis of the mechanism and phase portraits were used to identify the conditions that make the system unstable in terms of the kinetic coefficient of friction and angle of attack. Natural frequencies of the system were obtained from analytical, FEM and experiment models to confirm the design. To demonstrate the capability of the test apparatus, several materials pairs were tested. Measured motions and noises were processed to obtain frequency spectrums and time-frequency patterns. The automatic detection and rating algorithm previously developed by the author was applied to rate squeak propensities of the material pairs. An overall procedure comprised of design, analysis, test and signal processing is proposed to enable effectively handling of squeak problems in the design stage.