Assessment of longitudinal load spectrum characteristics and structural fatigue damage of metro vehicle body in service

Abstract

Aiming at the structural integrity requirements of service vehicles, there is an urgent need to construct a set of analytical methods based on service load characterization to realize the life assessment of the critical weak regions of the vehicle body. This study measured the longitudinal load spectrum of a metro vehicle body under a typical service line using a calibrated coupler and traction bar. Based on the signal characteristics of the longitudinal loads, a dynamic load feature decomposition method is proposed to decompose the longitudinal load features into trend and fluctuation signals to reflect the overall and local laws. The longitudinal load transfer characteristics of the vehicle body under traction, braking, linear, and curved conditions are innovatively analyzed, and a longitudinal load distribution ratio coefficient with generality is proposed as the input of effective service load. The service stress spectrum of the vital points of the vehicle body is constructed, which can more comprehensively and realistically respond to the service stress state of the vehicle body compared with the standard design loads, which further improves the accuracy of the structural integrity assessment.