RESUMO
This paper studies pattern noise in original equipment fitment through four approaches, including pitch arrangement optimization, pipe resonance experiment, orthogonal experimental design of tread transverse groove, and block shift simulation. An in-cab noise test is conducted to verify the effectiveness. Results show an 8.7% reduction in total harmonic energy and 12% decrease in the highest harmonic peak through pitch optimization. This paper introduces the 3-Sum concept to measure the difficulty of exciting a certain pitch harmonic. Meanwhile, the optimal width combination is found for central and shoulder longitudinal grooves. Transverse groove width, angle, and direction are studied using analysis of range and analysis of variance with the best match producing an indoor drum noise value of 76.09 dB. The simulation by the tread noise prediction system shows that the optimal misalignment of the central rib should be -7 mm, and its noise prediction value has a 2.21 dB(A) decrease from the original plan while the optimal misalignment of the shoulder rib is at its initial position. In the in-cab noise test, the sound pressure level of the optimized plan is reduced by 0.46 dB(A). Notably, the root mean square value within the frequency band 700-1300 Hz is reduced by 3.26 dB(A), which is a figure that fulfills the expected tread noise reduction.
