Finite Element and Modal Analyses of Rotor-Bearing Systems Under Stochastic Loading Conditions

Hashish, E.; Sankar, T. S.

doi:10.1115/1.3269159

Cited by 34 publications

(23 citation statements)

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“…Using the Newton-Raphson approach, (22) can be solved by iteration and {q 2 } t+ t can be obtained. Then, all that is needed is to solve the linear algebraic equations, (20), and determine {q 1 } t+ t .…”

Section: Partitioned Direct Integration Methods For Nonlinear Rotordynmentioning

confidence: 99%

“…[D e h ] is the hysteretic damping matrix of an element. The individual matrices appearing in the above equations are presented in detail in Nelson [20] and Hashish et al [22]. The flexible support model is described as eight spring and damping coefficients.…”

Section: Rotordynamics Modelmentioning

confidence: 99%

“…Internal viscous damping and hysteretic damping can be properly incorporated into the finite element model employing the virtual work principle in [22]. The viscous damping forces and moments due to hysteretic damping, expressed in (4) and (5), can be introduced into the element equations through the virtual work expression…”

Section: Rotordynamics Modelmentioning

confidence: 99%

See 2 more Smart Citations

Effects of flexible support stiffness on the nonlinear dynamic characteristics and stability of a turbopump rotor system

Chen

Wang

2010

Nonlinear Dyn

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Using a flexible support is an efficient approach to solving the subsynchronous problems in a turbopump. In this paper, nonlinear rotordynamic analysis of a liquid fuel turbopump with a flexible support is presented using a dynamic modeling including two key destabilizing factors, nonlinear hydrodynamic forces induced by seals and internal rotor damping. The methodology of the partitioned direct integration method (PDIM) is described for reducing the computational efforts efficiently. Combining the PDIM and the shooting method, a nonlinear stability analysis of the rotor system is performed effectively. The numerical results, which are in good agreement with test data, indicate that the effects of flexible support stiffness k on the dynamic characteristics and stability of the rotor system are significant. The first critical speed of the rotor system rises as a nonlinear function of k markedly. The second critical speed varies slightly and approximates a linear variation as k increases. The onset speed of instability of the rotor system rises initially and then reduces as k increases. The effect of seal nonlinearities at low k is contrary to that at high k and the effect of C. Bai ( ) · Q. Xu seal length on the system stability is more significant than that of seal radius. The results explain the nature of the subsynchronous motion of a turbopump rotor system with flexible support and can be used in the design and operation of a liquid fuel turbopump rotor system to eliminate its rotordynamic problem.

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Section: Partitioned Direct Integration Methods For Nonlinear Rotordynmentioning

confidence: 99%

Section: Rotordynamics Modelmentioning

confidence: 99%

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Effects of flexible support stiffness on the nonlinear dynamic characteristics and stability of a turbopump rotor system

Chen

Wang

2010

Nonlinear Dyn

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“…Several previous studies had focused on the dynamic characteristics of rotor systems subjected to random loads. Hashish and Sankar [1] demonstrated a simple procedure to calculate the stochastic response of a flexible rotor system. Namachchivaya [2] studied the mean-square stability of a rotating shaft under combined harmonic terms and stationary stochastic processes.…”

Section: Introductionmentioning

confidence: 99%

Stochastic finite element modeling and response analysis of rotor systems with random properties under random loads

2015

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Random properties and random loads are highly important in rotor dynamic analysis because they cause system dynamic responses to behave randomly. In this paper, a stochastical finite element of rotating shaft based on Timosheko beam theory is proposed for rotor system modeling, in which material and geometric random properties are considered one-dimensional stochastic field functions. A random response analytical method is developed to determine the statistics of the dynamic responses of stochastical rotor systems under random loads. The numerically obtained whirl speed of a turbopump rotor system is compared with the test data to validate the proposed model, and good agreement is observed. Linear and nonlinear turbopump rotor systems are employed to compare the results obtained from the proposed model and the Monte Carlo simulation. The numerically predicted results, which coincide well with Monte Carlo simulation data, demonstrate the feasibility and efficiency of the proposed stochastic model and method for actual rotor system analysis and design.

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“…However, the method worked for unbalance response but was not suitable for stability analyses. Hashish and Sankar (1984) . This provided an improvement in the modeling of the supports but this new technique could not be used for stability analyses.…”

Section: Introductionmentioning

confidence: 99%

Including the Effects of Flexible Bearing Supportsin Rotating Machinery

Vázquez

Barrett

Flack

2000

International Journal of Rotating Machinery

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Unbalance response and stability analyses of a flexible rotor on three lobe journal bearings on flexible supports are presented. The influence of the support structure was included in the analyses using polynomial transfer functions. These transfer functions were extracted from measured dynamic compliance data of the support structure, measured at the bearing locations. Numerical predictions using polynomial transfer functions and single mass supports are compared to the experimental data. Predictions using the transfer function representation of the support structure show a clear improvement over the predictions using single mass supports without over-complicating the problem. The predicted critical speeds are within 2.9% of the measured critical speeds. The predicted stability threshold agrees with the measured stability threshold within 1%. The effects of cross talk between supports and cross coupling between horizontal and vertical directions are investigated. The cross talk between supports was found to have a strong influence in the results while the influence of cross coupling between the vertical and horizontal directions is negligible.

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Finite Element and Modal Analyses of Rotor-Bearing Systems Under Stochastic Loading Conditions

Cited by 34 publications

References 0 publications

Effects of flexible support stiffness on the nonlinear dynamic characteristics and stability of a turbopump rotor system

Effects of flexible support stiffness on the nonlinear dynamic characteristics and stability of a turbopump rotor system

Stochastic finite element modeling and response analysis of rotor systems with random properties under random loads

Including the Effects of Flexible Bearing Supportsin Rotating Machinery

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