关键词: 地铁构架, 载荷识别, 阻尼比, 谐振范围, 疲劳评估

Abstract: The inversion of transfer matrix in dynamic load identification of engineering structures would produce errors. The load decoupling calibration method was used to diagonalize the transfer matrix to avoid errors caused by the inversion of transfer matrix. Thus, a high-precision force measurement frame with a measurement error of less than 5% was developed based on strain measurement principle, and a multi-source load decoupling identification method for metro bogie frames was established. Aiming at the problems that the frames were affected by wheel-rail excitation, resulting in a wide load band, causing resonance when the excitation frequency was close to elastic modal frequency of the frames, the load amplitude amplification effect near the resonance frequency was directly quantified in frequency domain through a second-order damping system, and the damping ratio was identified by least squares complex frequency domain method. The resonance range was determined by half-power bandwidth method and the calibration critical frequency was obtained. The load amplitude amplification effect was quantified and the load optimization factor was obtained. The effectiveness of the processed load was reflected to a certain extent based on vibration acceleration responses in resonance areas. In terms of time domain, frequency domain and damage, the load prediction stresses are close to the measured ones, and the ratio of predicted damage to actual damage is generally between 1.0 and 1.6, which meets the requirements of frame fatigue assessment. The results have important engineering significance for understanding the real load characteristics of metro bogie frames and exploring resonance fatigue problems.

Key words: metro bogie frame, load identification, damping ratio, resonance range, fatigue assessment