Research On Dynamic Characteristic Of Rotor Systems With Rub-impact Fault

Rotating machinery usually refers to machinery and equipment with rotary motion parts, which is one of class of mechanical equipment most widely used in the industrial sector. Rotor-bearing system as core components of rotating machinery, are widely used and play an irreplaceable role in defense, energy, electricity, transportation and chemical sectors. Excessive vibration of rotor system is the main cause of failure. The vibration include shaft torsional vibration, bending vibration, the disk vibration, bearing vibration, and pipe vibration. Since rotating machinery applications in different fields, in which the work environment is also different, there are a variety of reasons induced the rotor failure. The most common faults are rub-impact, misalignment, cracks, oil shocks, loose, etc. In addition to the single failure, but also various types of coupling faults occur, which vibration feature is more complex.This paper mainly researches vibration characteristics of rubbing of rotor system. Using rotor dynamics theory, build lumped mass model of system. With numerical and experimental methods studies the dynamic properties of simple rotor system in different rubbing models and misalignment-rubbing coupling faults. This work includes the following aspects:(1). Introduce the basic theory of rotor-stator rubbing and numerical algorithm, and build the single-point rubbing model. Based on nonlinear theory and numerical solution, researches dynamics properties of rotor system in the case of single-point rubbing, investigate the effects of rubbing parameters on the single-point rubbing, discuss the system movement regularity from P1to P2, P2to P3, P3to P4. At last compare with experimental data for proving.(2). Building the system dynamics model of local rub-impact, analyse the effects of rubbing parameters on dynamics properties of local rubbing, and compare with single-point rubbing model, finding that local rubbing also has period movement regularity, but the mode of movement performs more complexly, and that non-linear characteristics are more prominent.(3). Based on Hertz contact theory, build dynamic model of Hertz contact rubbing. And on this basis, respectively, do the simulations to the single-point rubbing and the local rubbing, compared with the piecewise linear stiffness model and find that, Hertz contact rubbing force model express contact between stator and rotor with the material properties, closer to the actual situation, but the Hertz contact model has greater restriction in the use.(4). Building the misalignment dynamic model of single-span rotor system, do the simulation analysis to the vibration response of rotor system with misalignment faults under different impact parameters, finding that the vibration characteristics of the rotor system with misalignment faults are obtained as following:there is not only rotating frequency but also multiple frequencies appearing in the spectrum, and the ratio of the multiple frequencies increase with the rise of the degress of misalignment. Under the condition of misalignment, the shaft center orbit presents a "banana" shape or "water-drop" shape.(5). Build misalignment-rubbing coupled dynamic model of single-span rotor system, do the overall analysis to vibration characteristics when the system is at different speeds, different Rubbing stiffness and the different degree of misalignment, compared with dynamics properties of rubbing only and misalignment only, find that coupling fault is not only the simple superposition of a single fault, in addition to characteristics of rubbing and misalignment, there are also some unique characteristics of the coupling fault.(6). Build loose-rubbing coupled dynamic model of single-span rotor system, do the overall analysis to vibration characteristics when the system is at different speeds, different rubbing stiffness and the different loose stiffness, find that coupling fault is not only the simple superposition of a single fault, in addition to characteristics of rubbing and loose, there are also some unique characteristics of the coupling fault.