This study experimentally investigated the influence of angular distribution of a grooved surface on wear properties as well as friction-induced vibration and noise characteristics. The surfaces of brake disc material were modified by cutting grooved surfaces with different angular distributions. The differences between the grooved and smooth surfaces in friction and wear and friction-induced vibration and noise were evaluated. This was performed via a pad-on-disc test configuration where the brake pad material was used as a counterface. The test results indicated that all the grooved surfaces with different angular distributions had significant potential in improving friction and wear behaviors of the contact surfaces and also in reducing the amplitudes of high-frequency vibration accelerations and noise pressure levels. Additionally, the results indicated that the ability of the grooved surfaces to suppress the generation of noise is closely related to the angular distribution of the grooves and the interference length of the grooved surfaces on the contact interface. The grooved surface allowed for entrapping and exhausting wear debris from the contact interface, which improved the wear status, and this was one of the reasons for the noise reduction of the grooved surface to a certain extent. Meanwhile, another reason was that the grooved surface interrupted the concentrated contact pressure and changed the contact pressure distribution on the leading edge of the contact surface.

This practice provides information for combining standard uncertainties of Fe in metallic silicon determined by the ICP-AES method of the China Inspection and Quarantine (CIQ). The measurand Fe% is determined from other quantities p.q.r. . . through a functional relationship of the model f: Fe% = f(p.q.r . . .). The estimated standard deviation associated with the output estimate Fe%, called combined standard uncertainty and denoted by uc (Fe%), is determined from the estimated standard deviation associated with each larger input estimate (p.q.r . . .). The combined variance u2c (Fe%) can be viewed, by the sensitivity coefficients, as a sum of terms with the minor errors omitted.