Papers by Keyword: Pedestal Looseness

Abstract: The dynamic model of nonlinear stiffness rotor-bearing system with pedestal looseness fault was set up, taking the linearity and cube item as the physics nonlinear factors. The periodic solution of system was analyzed by continuation-shooting algorithm for periodic solution of nonlinear non-autonomous system, and the stability of system periodic motion and unsteady law are discussed by Floquet theory. The unstable form of it is Hopf bifurcation. In the region of critical rotate speed, the main motion of the system is periodic-4; and it of ultra critical rotate speed, the main motion of the system is periodic-3 and chaotic motion. The conclusions provide theoretic basis reference for the fault diagnosis of the rotor-bearing system.

Abstract: On the basis of the dynamic equations of rotor system with pedestal looseness, the random response method of rotor system with pedestal looseness is researched. The method is based on stochastic perturbation theory and the Kronecker algebra, matrix calculus and random perturbation are used. The reliability model of rotor system with pedestal looseness is proposed. The reliability of rotor system with pedestal looseness is obtained by way of statistical fourth moment method, random perturbation technique. Numerical results are also presented and discussed.

Abstract: The dynamic model of two-span rotor-bearing system with three-coupling faults of rub-impact, crack and pedestal looseness faults was set up, and the influences of faults to nonlinear dynamic characteristics of the system were studied by mapping and continuation comprehensive method. There are many harmonic elements of 1/3, 1/2, 2/3, 1, 3/2 and 2 et al within the sub-critical rotate speed range. But the 3/2 and 2-harmonic elements decrease within the super-critical rotate speed range. It may the main characteristics of the system with three-coupling faults of rub-impact, crack and pedestal looseness. It should notice to diagnosis the three-coupling faults of the system when running within the super-critical rotate speed range.

Abstract: The dynamic model of the pedestal looseness fault rotor-bearing system with slowly varying mass was set up. The complex characteristics of the rotor-bearing system were numerically studied. Along with the increase of the looseness mass, the chaotic motion area and amplitude range increase in the region of critical rotating speed; and P-3 motion area disappears in the region of twice-critical rotating speed, chaos is the main motion form. Along with the increase of the coefficient of mass slowly varying amplitude, the instable rotating speed increase, and the chaotic motion area decreases, P-n motion area increases in the region of critical rotating speed and twice-critical rotating speed. The conclusions may provide basis reference for fault diagnosis.

Abstract: Looseness fault can occur in rotor part, bearing and pedestal for the vibration caused by alteration of operating craft and inappropriate installation. In the paper, a new pedestal looseness model is proposed by comprehensively considering the advantages and disadvantages of current models of pedestal looseness. By using nonlinear finite element method, the nonlinear characters of overhanging dual-disc rotor bearing for pedestal looseness fault are studied. The work has important significance on safe running and prolonging the life span of machines.