The aim of this paper is to gain insight into the nonlinear vibration feature of a dynamic model of a gas turbine. First, a rod fastening rotor-bearing coupling model with fixed-point rubbing is proposed, where the fractal theory and the finite element method are utilized. For contact analysis, a novel contact force model is introduced in this paper. Meanwhile, the Coulomb model is adopted to expound the friction characteristics. Second, the governing equations of motion of the rotor system are numerically solved, and the nonlinear dynamic characteristics are analyzed in terms of the bifurcation diagram, Poincaré map, and time history. Third, the potential effects provided by contact degree of joint interface, distribution position, and amount of contact layer are discussed in detail. Finally, the contrast analysis between the integral rotor and the rod fastening rotor is conducted under the condition of fixed-point rubbing.
We study the effect of pressure on Raman spectra as well on magnetic properties of molecule-based magnets KNiCr(CN)6 and KMnCr(CN)6. The effect of pressure on the ν[C≡N] vibration band which is located in the 2100–2200?cm?1 spectral range is relatively weak. Hydrostatic pressure has small almost a negligible effect on the Curie temperature of ferromagnetic KNiCr(CN)6 while leads to a pronounced reversible Curie temperature increase occurrence of new magnetic phase under pressure in the case of KMnCr(CN)6. Applied pressure affects magnetization curves only marginally. All pressure-induced changes are reversible. 相似文献
Results from theoretical and experimental investigations into the nonlinear deformation (geometrical nonlinearity, plastic
deformation, creep) and critical states (limit loads, buckling) of shell-frame systems with geometric imperfections are analyzed.
The presence of prestresses is allowed. Diverse effects of various geometrical imperfections and plastic deformation for different
load histories are studied. New qualitative effects of the mutual influence of these factors are established. Relevant experimental
results are outlined
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 12, pp. 3–47, December 2006. 相似文献