| The antenna beam is important equipment because it carries the ATP antenna. Theoretically, the ATP system can automatically protect the vehicle, making the antenna beam critical for safe driving. However, in practice, cracks were found in the antenna beam welding seam. These cracks would have negatively influenced the safety of the vehicle.This paper, based on the antenna beam cracks situation, analyzes the dynamic properties of the antenna beam to find out the reason for the cracks and the way to optimize the antenna beam by using the method of finite element simulation. The specific steps are as shown below:Firstly, finite element simulation analysis was applied to the antenna beam to understand the dynamic characteristics and obtain modal vibration mode. Response of measuring point in different direction harmonic load was obtained through harmonic response analyses.Secondly, the author calculated the antenna beam fatigue damage and life time for test points on antenna beam based on rush hour test data in Subway Line4. According to stress distribution law of measuring point, the weak point was found by inferring the maximum stress. The weak point was found to be the weld line between strengthening tendon-plate and steel tube.Thirdly, using FFT transforms focusing on operating condition and velocity condition, frequency domain analysis for the dynamic stress signal of key points and acceleration signal of key points was performed. The results showed that down line operation conditions are severe. Even though the vehicle was driven at a constant speed, the antenna beam was rigorously vibrating. The vibration table tests indicated that single direction load cannot cause fatigue failure. Finally, the size and shape of the antenna beam is optimized by using simulation software. The first-order mode of antenna beam is improved which played an active role in avoiding resonance. |
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