Тhe influence of the trailer center of mass displacement on the motion stability of an articulated bus
DOI:
https://doi.org/10.36910/0bt3nb30Keywords:
Keywords: articulated bus, trailer, eccentricity, center of mass, mathematical model, stability, critical speed.Abstract
Given the rapid increase in the number of vehicles in large cities, which complicates the functioning of passenger transport systems, the issue of their improvement has become particularly relevant. A key direction in this context is reducing the load on the urban road network.
The present study focuses on the possible displacement of the center of mass of the trailer unit under conditions of high passenger occupancy in both the bus and trailer bodies during peak hours, which may lead to a deterioration in the motion stability of an articulated bus. It has been established that the eccentricity of the trailer’s center of mass results in an ambiguous effect on the slip and articulation angles of the vehicle combination. When the trailer center of mass shifts outward relative to its instantaneous center of rotation, both the slip and articulation angles increase compared to the case of symmetric loading (ε = 0). Conversely, when the center of mass shifts inward, these angles decrease.
Such changes in the slip and articulation angles lead to almost corresponding variations in angular velocity, lateral velocity, and lateral acceleration of the trailer’s center of mass. However, regardless of the displacement of the trailer’s center of mass, at a speed of 10 m/s the articulated bus remains stable. An increase in vehicle speed results in a deterioration of motion stability, and at an eccentricity of ε = 0.2 the vehicle operates at the stability limit (the allowable acceleration of the center of mass should not exceed 0.45g).
Unlike transient motion modes (cornering, lane change), in steady-state conditions (straight-line motion), the presence of eccentricity leads to a decrease in critical speed regardless of the direction of displacement. In particular, in the absence of eccentricity the critical speed is Ve=0=0 = 28.12 m/s; with outward displacement Ve=0 = −0.2 = 23.95 m/s; and with inward displacement Ve=0 = 0.2 = 24.89 m/s. These factors must be considered when loading the trailer.
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