Case study: An improvement study of damping ring applied to wheel noise and vibration control

The friction damping (FD) ring is a kind of low-cost and efficient damping device that has been used for decades in noise and vibration control of railway wheels. Preload is one of the most important parameters that affect the noise reduction effect of an FD ring. An acoustic characteristic test of a railway wheel with a rectangular cross-section FD ring under different preloads was carried out in the laboratory. The noise results show that there is an optimum preload that makes the total sound pressure level (SPL) of the wheels the lowest. However, at the same time, a new phenomenon in which the noise attenuation time increased with the increase in preload was observed. The phenomenon is explained by acoustic and modal tests, as well as a single degree of freedom system. Modal results show that, with the increase of the preload on an FD ring, modal damping of several modes of the wheel was correspondingly reduced, and the duration of noise was lengthened accordingly. To solve this problem, a new type of constrained layer damping (CLD) ring was designed based on the modal strain energy (MSE) method. A comparative experiment was conducted between the CLD ring and FD ring, including an acoustic test and modal test. The modal test results show that the CLD ring can provide a greater damping ratio in most frequencies of the wheel, especially the low frequencies corresponding to the noise attenuation time. Acoustic results show that the CLD ring has superior performance both in the time domain and frequency domain to the FD ring.