Sensing and Quantifying a New Mechanism for Vehicle Brake Creep Groan

Abstract

This paper investigates the creep groan of a vehicle’s brake experimentally, analytically, and numerically. Experimentally, the effects of acceleration on caliper and strut, noise, brake pressure, and tension are measured. The results show that the measured signals and their relevant spectra broadly capture the complex vibrations of creep groan. This includes the simple stick-slip, severe stick-slip vibrations/resonances, multiple harmonics, half-order harmonics; stick-slip-induced impulsive vibrations, steady/unstable vibrations, and their transitions. Analytically, a new mathematical model is presented to capture the unique features of half-order harmonics and the connections to fundamental stick-slip/resonant frequency and multiple harmonics. The analytical solution and the experimental results show that the vibro-impact of the brake pad-disc system can be triggered by severe stick-slip vibrations and is associated with instable, impulsive stick-slip vibration with wideband. The induced stick-slip vibro-impact can evolve into a steady and strong state with half-order, stick-slip fundamental, and multiple-order components. This new mechanism is different from all previously proposed mechanisms of creep groan in that we also view some type of creep groan as a stick-slip vibration-induced vibro-impact phenomenon in addition to conventional stick-slip phenomena. The new mechanism comprehensively explains the complex experimental phenomena reported in the literature. Numerically, the salient features of phase diagrams of instable stick-slip and vibro-impact are examined by using a seven-degree-of-freedom brake system model, which shows that the phase diagrams of the dynamics of creep groan with and without vibro-impact are substantially different. The phase diagram of the dynamics with vibro-impact is closer to the experimental results. In contrast to existing mechanisms, the proposed new mechanism encompasses the instable stick-slip nature of creep groan and elaborates the inherent connections and transition of the spectrogram. The new knowledge can be used to attain critical improvements to brake noise and vibration analysis and design. By applying the proposed new model in addition to existing models, all experimental phenomena in creep groan are elaborated and quantified.

Stick–Slip Characteristic Analysis of High-Speed Train Brake Systems: A Disc–Block Friction System with Different Friction Radii

“…The results showed that increasing the circular frequency would stimulate a higher response frequency from the system energy, which was close to a certain natural frequency of the friction system. Meng et al [35] proposed a new model to quantify the stick-slip groaning of an automotive brake system. The results showed that the vibration shock of the pad-disc system was triggered by stick-slip vibration and was closely related to the wide-band instability and pulsed stick-slip vibration.…”

A Method for Quantifying Automobile Brake Creep Groan Intensity Based on Friction‐Induced Vibration and Noise

“…Analytically, previous studies [17,18] focusing on exploring the mechanism of creep groan have revealed that the sources of creep groan caused by brake self-excited vibration include unstable sliding in addition to transient or steadystate stick-slip motion between pads and discs of impulsive and discontinuous nature. After in-depth analysis of the mechanism of creep groan, the establishment of the models that can quantify and predict brake friction-induced vibration and noise has become a research field.…”