Research on the dynamic characteristics of the dynamic track stabilizer side searing
The dynamic characteristics of side bearing are one of the key factors for further study on the overall behaviour of the dynamic track stabilizer. The constitutive parameters of rubber spring were determined by the static experiment. Based on the parameters, the finite element model of side bearing was built and the reliability of side bearing model was verified by experiment. The vertical dynamic characteristics of side bearing were studied on the base of LS-DYNA. According to the analytical results, the dynamic characteristics of the side bearing spring constants and its internal damping are nonlinear under different compound of loads and frequencies. The conclusion can provide a theoretical basis to the optimal design of the side searing.
Modeling and experimental research of ring-like metal rubber isolator system
The modeling and experimental research of Ring-like MR isolator is investigated to satisfy the need of vibration system of aircraft engine's plug.The modeling of the isolation system is explored,and the parameters are discussed based on the principles of dynamics and Hysteresis theory,and the dynamic frequency response characteristics of isolation system are obtained.The local stiffness of the Ring-like MR isolator is analyzed by static experiment based on different beginning deformation, and it is testified by the dynamic experiment.The results show that this kind of isolator has special stiffness and damping characteristics, and its initial deformation has a great influence on the nature frequency and transmissibility.7figs.,1tab.,11refs.
Turbulent boundary layer wall‐pressure fluctuations downstream from an abrupt change in surface roughness
Spectra of wall‐pressure fluctuations beneath a turbulent boundary layer have been investigated immediately downstream from an abrupt change in surface roughness, from slightly rough to very rough. Over the measurable frequency band (400 Hz to 7 kHz), the spectra in the first 150 mm scale on wall variables. This indicates that the motions responsible for the pressure fluctuations measured in this region are very close to the wall. Farther downstream this scaling procedure breaks down. It is suggested that the initially thin internal layer behaves independently of the flow external to it until it has grown appreciably and only then interacts with the outer boundary layer. It was found that, for all frequencies measured, the dimensional spectral level decreases initially then rises to a maximum at 250 mm from the roughness change before decreasing once more. The position of the maximum is close to where the internal layer ceases to have a distinct edge.