• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2026, Vol. 62 ›› Issue (14): 347-354.doi: 10.3901/JME.260480

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Study on the Development of Three-dimensional Spectrum Incorporating Frequency-amplitude-count

MA Juefan, REN Zunsong, AN Rui   

  1. School of Mechanical, Electrical & Control Engineering, Beijing Jiaotong University, Beijing 100044
  • Received:2025-09-05 Revised:2026-01-15 Published:2026-08-29

Abstract: In current studies, stress spectrum constructed using the rainflow counting method are typically two-dimensional, consisting only of amplitude and count. However, such spectrum don’t capture the frequency information of the signal, limiting the ability to assess the contribution of stresses from different frequency domains to structural damage. Therefore, it is necessary to develop a method for constructing a three-dimensional spectrum that incorporates signal frequency. In this paper, we propose a method based on the rainflow counting technique to obtain the time intervals and frequencies of rainflow cycles. This enables us to determine the frequency and amplitude of each rainflow cycle, resulting in the establishment of a three-dimensional stress spectrum that includes frequency, amplitude, and count. Using dynamic stress test data from the bogie frame of a vehicle operating on a specific line of the Beijing Subway, we analyzed the frequency-domain characteristics of the dynamic stress signals. We identified the frequency levels that effectively represent the signal’s frequency-domain features and developed a three-dimensional stress spectrum for the motor hanger on the bogie frame. The validity and accuracy of the proposed three-dimensional spectrum were verified. Additionally, we explored the effect of different train speeds on the dynamic stress frequency domain of the structure and constructed three-dimensional stress spectrum at three distinct speed levels for the measurement point. This analysis allowed us to quantify the contribution of different speeds to the equivalent stress. The results demonstrate that the proposed method for constructing a three-dimensional spectrum incorporating signal frequency can effectively extract frequency information and reflect the contribution of dynamic stresses in different frequency domains to the structure’s equivalent stress. These findings provide a foundation for further research into the impact of elastic vibrations on structural damage.

Key words: 3D spectrum, development method, rainflow counting, frequency, amplitude

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