亚洲 欧美 图片 自拍 视频

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          Test and Simulation Analysis of Vehicle Rearview Mirror Jitter

          1 Overview

          The exterior mirror is one of the important devices for the active safety of the car. It is a tool for the driver to obtain external environmental information on both sides and the rear of the car. It is also an important tool for ensuring the safety of the car. During vehicle driving, road surface excitation, engine and transmission system vibrations will all cause body vibrations, which may cause rear-view mirrors to shake to varying degrees. Severe shaking will cause unclear vision in the rear, causing the driver to make a traffic accident due to misjudgment. According to literature statistics, China's traffic accidents caused by defects in the design and manufacture of rearview mirrors account for 30% of the total number of traffic accidents, while the United States accounts for 20%, especially on highways, this proportion is as high as 70%. Therefore, in addition to meeting the requirements of relevant regulations and standards, the rearview mirror must reasonably choose the radius of curvature, the size of the mirror surface, and the installation position, and it must pay attention to the dynamic characteristics of the rearview mirror.

          2 Questions raised

          During the road test of a domestic passenger car, it was found that the rearview mirror not only severely shakes under idle conditions, but also has obvious vibration when driving on high speeds and rough roads. Obscuring the driver's visual field of vision not only easily causes driver's eyesight fatigue, but also cannot timely and accurately judge the situation on both sides and the rear, which poses a large potential safety hazard. This article analyzes and improves this problem.

          3 Experimental modal analysis

          In order to obtain the real working condition of the rearview mirror, a test is carried out on the entire vehicle, and hammer excitation is used to test the dynamic characteristics of the rearview mirror. The data acquisition front end of the experiment adopts SCADIII of LMS company, the HEV200 of PCB company is used as the hammer, the three-way acceleration sensor of PCB company is used as the sensor, and the data analysis and processing software adopts Test.LAB 9 etc.

          See Figure 1 for sensor placement

          newmaker.com

          Figure 1 Rearview mirror sensor placement

          The data collection cut-off frequency is 512Hz and the frequency resolution is 0.5Hz. The following results can be obtained by analysis:

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          Figure 2 Modal calculation results of rearview mirror

          From the test results, it can be seen that the modal frequency of the rearview mirror is relatively low, and it is easily excited by the engine, the transmission system, and the road surface, which is an important reason for the jitter of the rearview mirror.

          4 Numerical simulation analysis of rearview mirror

          In view of the problem of rear-view mirror jitter in this car, it would be difficult and time-consuming to simply use the test method to find the cause of the problem. In order to quickly find out the design defects of the structure and put forward modification suggestions, this paper uses a simulation method to carry out structural modal analysis on the structure of the rearview mirror, check to find out the problems in the structure, and propose suggestions concerning changes.

          4.1 Establishment of finite element model

          In order to make the modal analysis of the rearview mirror close to the actual situation, the rearview mirror is installed on the front door for analysis. The finite element model of the rearview mirror and the front door is completed in HyperMesh. In the model, the tetrahedral element TETRA4 is used, and the element division of the sheet metal parts is mainly the quadrilateral element CQUAD4, the transition element is the triangular element CTRIA3, and is controlled within 3%, the hinge axis is simulated by the RBE2 element, and the welding point is performed by the CWELD element The simulation and glue are simulated by solid units. The finite element model is shown in Figure 3:

          newmaker.com

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          亚洲 欧美 图片 自拍 视频
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