| As people increasingly high demand for the car ride comfort, vehicle’s NVH performance has been achieved more concern from customer. Disc brake NVH characteristics as part of the vehicle NVH performance, is of great significance to study it and optimize. The main evaluation index of disc brake NVH attribute is the brake noise, studying and optimizing disk brake NVH characteristic is the study of automotive brake noise generation mechanism and how to reduce automobile brake noise.This paper is firstly accessed to relevant literatures and describes the basic structure and operation principle of disc brake, the international classification and influencing factors of brake noise are discussed in the paper.Based on the research status of brake noise in domestic and overseas, main research contents and research methods are put forward. New type brake pad with three layers is proposed according to the research and summary on mechanism of brake noise generation, the friction material is composed by Mix layer and UL layer, which can guarantee the same braking strength and increase the damping characteristics by changing the material of UL layer. Ten DOF dynamic models is built according to the new design brake pad, with kinematics equation, detailed analysis of the causes of brake noise and structural features of the sub-parameters affecting the brake noise is generated.Product’s design and development in domestic OEM is reverse design, based on reverse engineering technology, 3D models of caliper and support of the brake are built in this paper, surface texture parameters’ point cloud data is acquired by 3D laser scanner and models are done by several operations in Catia such as noise reduction of point cloud data, surface reconstruction. For the other components like rotor and brake pad which are simple and can be measured easily are finished in Solidworks. Real modal analysis is applied on sub-components of brake system which can provide the frequency and mode shape that are close to each other, complex modal analysis is carried out on brake assembly in workbench to extract unstable modes which can forecast brake noise. Additionally, the influence of friction coefficient, brake pressure, simplified model, friction damping and damping material on unstable modes were studied.Experimental study is an essential part of the research on brake noise. The density and mechanical properties test were carried out in this paper to achieve accurate material properities, modal parameters of brake pad like modal frequency and modal shape were measured by Impacting test and laser vibration detector which were used to testify the accuracy of simulation result done by FEA. Noise bench test was carried out on LINK 3900 multi-channel noise dynamometer to obtain the brake noise result. The noise result was anastomotic with simulation result, however, brake NVH performance should be further optimized. Optimization methods were studied and summarized at the beginning, and then methods of changing the viscoelastic composition ratio of UL and the pad shape were chosen for the further optimization. According to the result of simulation and experiment, brake NVH performance was improved dramatically, brake noise was suppressed.Simulation analysis and experimental research conducted in this paper provide a strong, accurate theoretical and experimental basis for disc brake design theory and NVH optimization. |
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