Experimental Study On Mechanical Properties Of Air Springs For Railway Vehicles

Based on the theoretical researches made by scholars at home and abroad, and according to the requirement needed for the studies of air spring mechanical properties, by using three kinds of test benches and the established related test methods, the experimental researches are conducted for the vertical and lateral mechanical properties of the single-air-spring system, and also the double-air-spring system with two-point and four-point controls.In the experimental research of air spring vertical mechanical properties, the relationship of air spring deformation with respect to the static stiffness, the effective area and the change rate was found. The impacts of the structure parameters such as different orifice diameters, auxiliary tank volume, connecting pipe diameter, etc., along with the amplitude and frequency of excitations on the dynamic characteristics of the air spring were compared. The test results showed that the vertical mechanical frequency behavior of the air spring was related to the physical parameters:the dynamic stiffness of the air spring with bellows-orifices-auxiliary tanks firstly increased and then became stable when the excitation frequency went up, while the damping ratio firstly went up and then down to the bottom. However, along with the increasing of the excitation frequency, the dynamic stiffness of the air spring equipped with connecting pipe firstly decreased then increased to the top and then decreased and finally became stable and closed to the stiffness when the bellow worked alone, while the damping ratio increased at first and then decreased as previous.Except the influence of frequencies and amplitudes of the excitations, the lateral and torsional mechanical properties of air springs were affected by rubber cord angle and material of the bellows, while the structural parameters of air spring system such as auxiliary tanks volume showed little effect on the mechanical properties.Results of the comparison between two-point and four-point controls for the air springs showed that the excitation phase angles had vital importance on the dynamic stiffness in the low-frequency region by using two-point control method rather than the four-point control method, especially when the excitation is in opposite direction, stiffness of the air spring went down to zero. Besides, the orifice diameter and auxiliary tanks also affect dynamic frequency behavior of the air spring system.