Development of Noise Propensity Index (NPI) for Robust Brake Friction

Jae Seol Cho, Jong Yun Jeong, Hyoung Woo Kim, Hwa Sun Lee, Yang Woo Park, Junghwan Lim, Yoonjae Kim, Jinwoo Kim, Byung Soo Joo, Ho Jang

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


A semi-empirical index to evaluate the noise propensity of brake friction materials is introduced. The noise propensity index (NPI) is based on the ratio of surface and matrix stiffness of the friction material, fraction of high-pressure contact plateaus on the sliding surface, and standard deviation of the surface stiffness of the friction material that affect the amplitude and frequency of the stick-slip oscillation. The correlation between noise occurrence and NPI was examined using various brake linings for commercial vehicles. The results obtained from reduced-scale noise dynamometer and vehicle tests indicated that NPI is well correlated with noise propensity. The analysis of the stick-slip profiles also indicated that the surface property affects the amplitude of friction oscillation, while the mechanical property of the friction material influences the propagation of friction oscillation after the onset of vibration. An additional case study for noise reduction was carried out using commercial brake friction materials before and after the modification of NPI. The results of the case study based on in-vehicle noise tests indicate that a robust friction material can be designed by reducing the stiffness ratio and large contact plateaus on the sliding surface of brake friction materials.

Original languageEnglish
Pages (from-to)589-595
Number of pages7
JournalSAE International Journal of Commercial Vehicles
Issue number2
Publication statusPublished - 2017 Sept 17

Bibliographical note

Publisher Copyright:
Copyright © 2017 SAE International.

ASJC Scopus subject areas

  • Automotive Engineering


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