Abstract:

In this paper， a nonlinear dynamic stiffness model of rolling-lobe air spring with consideration of the Payne effect of the rubber and the hysteresis characteristics of the thermodynamic equivalent stiffness and damping is proposed to overcome the difficulty in modeling the nonlinear dynamic stiffness of air spring and provide a theoretical basis for the structural design and material selection of rolling-lobe. Firstly， parameter identification is conducted for the real and imaginary parts of dynamic stiffness by indicator diagram test， showing that the Payne effect of rubber causes the increase of dynamic stiffness under small amplitude with the correctness of the model under the excitations with different amplitudes and frequencies verified. Then， the physical explanation of the changing trend of the contribution of each decoupled variables is given from the two dimensions of amplitude and frequency. The results indicate that due to the Payne effect of the rubber， the real part of dynamic stiffness reduces and its imaginary part increases first and then gradually reduces with the increase of amplitude. And due to the stiffness of air and the equivalent damping generated by heat exchange， the real part of dynamic stiffness gradually increases and its imaginary part increases first and then reduces with the increase of frequency. Finally， a new evaluation indicator reflecting the contribution ratio of the dynamic stiffness of the rubber lobe is given， which can directly characterize the low-amplitude dynamic performance and the rationality of structural design and material selection of air spring. The test results indicate that this indicator obviously reduces with the increase of amplitude， so the dynamic stiffness at low amplitude generated by rubber lobe should not be ignored.

Key words: Payne effect, thermodynamics, hysteretic characteristics, nonlinearity