Frequency Reliability Sensitivity Research Articles

Reliability sensitivity estimation of rotor system with oil whip and resonance

Oil whip and resonance are the common faults of a rotor system. The faults directly affect its normal operation and can cause serious accidents. Based on the regularity of oil whip and resonance of the rotor system, a sensitivity study of the frequency reliability of the system is conducted. The technique developed utilizes random perturbation technology, reliability theory, and sensitivity technology. The reliability mode and the failure probability of the rotor systems are defined. The second-order joint failure probability is obtained using numerical integration methods. The variation regularities of the reliability are obtained and the influences of random parameters on the reliability of the rotor system are studied. The method presented provides a theoretical basis for the frequency reliability sensitivity design of the rotor system. A numerical example is analyzed to show the effectiveness of the proposed method.

RESEARCH ON THE FREQUENCY RELIABILITY SENSITIVITY AND RELIABILITY-BASED ROBUST DESIGN OF THE RANDOM VIBRATION SYSTEM OF CONTINUOUS ROD

The frequency reliability sensitivity in the stochastic dynamic structure system and reliability-based robust design were studied deeply in this paper. With the criterion that the absolute value of the difference between natural frequency and forcing frequency, the frequency reliability method of avoiding resonance was proposed. Then frequency reliability sensitivity theory was presented, which provided a preliminary efficient way to analyze how each random parameter contributed to the system reliability. Moreover, the frequency reliability-based robust design method was obtained by robust and optimization technology on the basis of the frequency reliability and sensitivity research in the paper, which helped designers to establish acceptable parameter values and to determine the fluctuations of the parameters for the safe operations. Meanwhile, a numerical example of the random vibration system of continuous rod was provided and studied. The effectiveness and accuracy of the proposed methods were well demonstrated.

Frequency Reliability-Based Robust Design of the Suspension Device of a Jarring Machine with Arbitrary Distribution Parameters

The frequency reliability with arbitrary distribution parameters in the stochastic dynamic structure system of practical engineering and its related theories were studied deeply in the paper. The frequency reliability method of avoiding resonance was proposed by mechanical dynamics, stochastic finite element method, and reliability theory. Then the frequency reliability formula with arbitrary distribution parameters was deduced through Edgeworth series method. Furthermore, the frequency reliability sensitivity method was presented based on the frequency reliability research, which provided a preliminary efficient way to analyze how each random parameter contributed to the system reliability. Moreover, the frequency reliability-based robust design method of the stochastic dynamic structure system was obtained by robust and optimization technology on the basis of frequency reliability and sensitivity method, which helped designers to establish acceptable parameter values and to determine the fluctuations of the parameters for the safe operations. Meanwhile, a numerical example of the suspension device of a jarring machine with arbitrary distribution parameters was provided and studied, the numerical results were in agreement with practice, which demonstrated the efficiency and accuracy of the proposed methods.

Frequency Reliability Sensitivity and Robust Analysis for the Random Axial Vibration of Rod Systems

The paper is concerned with the frequency reliability sensitivity and related robust analysis problem for the random continuous vibration structure systems. Reliability analysis based on frequency is necessary for reliability problems of uncertain vibration structure systems. With the criterion that the absolute value of the difference between the natural frequency and forcing frequency, the reliability mode and the safety probability of the random systems are defined, and then The frequency sensitivity analysis method is quested by using the random perturbation technique, the reliability theory and sensitivity approach. Furthermore, the frequency reliability-based robust method of the random dynamic structural system was obtained by the robust and the optimization technology on the basis of frequency reliability and sensitivity design, which helped designers to establish acceptable parameter values and to determine the fluctuations of the parameters for the safe operations. Moreover, a numerical example is provided to demonstrate the effectiveness and accuracy of the proposed method. This study established theory basis for sensitivity and robust evaluation.

Frequency Reliability Sensitivity Analysis for Rotor System with Random Parameters

The random factor method (RFM), an effective numerical simulation method, is employed to analyze the probabilistic characteristics and reliability sensitivity of uncertain structure system. The natural frequencies of the system can be expressed as the function of the random factors. By using the random variable’s algebra synthesis method, the expressions for the mean value and standard deviation of natural frequencies are derived from Rayleigh quotient. The reliability mode and the safety probability of random systems are defined, and then the frequency reliability sensitivity analysis method is presented. The formulas of failure probability sensitivity are derived when random variables are normally distributed. The reliability index is evaluated, and its sensitivity to mean values and variances are mathematically expressed, then the efficiency and accuracy of the proposed method are demonstrated by a numerical example.

Frequency Reliability-Based Robust Design of the Random Dynamic Structural Systems

The frequency reliability.method of avoiding resonance is proposed by the mechanical dynamics, stochastic finite element method, the reliability theory in the paper. Furthermore, the frequency reliability sensitivity method is presented based on the frequency reliability research, and the frequency reliability-based robust method is obtained by the robust and the optimization technology on the basis of frequency reliability and sensitivity design, which help designers to establish acceptable parameter values and to determine the fluctuations of the parameters for the safe operations. Moreover a numerical example is provided, the frequency reliability robust numerical results are obtained, which are in agreement with practice and demonstrate the effectiveness and accuracy of the proposed method.

Frequency Reliability and Sensitivity Analysis on the Rotor System

Multispan rotor system(H858 compressor) is studied in this paper. Based on the rotor dynamic theory, complex rotor system is simplified reasonably, and finite element model is established using finite element software(MSC.Patran&Nastran). The natural frequencies are obtained in the condition of bending vibration, and the functions of frequencies and variables are matched on the basis of the artificial neural network (ANN) technique. With the criterion that the absolute value of the difference between the natural frequency and forcing frequency, the reliability mode and the systems safety probability are defined, then the frequency reliability sensitivity analysis method is presented. And the equations of the related sensitivity with respect to mean values and variances are mathematically expressed. The reliability and sensitivity of rotor system are analyzed, which demonstrate the effectiveness and accuracy of the proposed method.

Frequency Reliability Robust Optimization for Rotor System

The material properties and geometry of rotor system are random parameters because of the manufacturing environment, manufacturing and installation errors and other factors. Based on the reliability design theory, the reliability sensitivity technique and the robust design method, the frequency reliability robust optimization method of rotor system is extensively discussed. The frequency reliability sensitivity is added to the reliability-based optimization design model of rotor system. The frequency reliability robust design is described as a multi-objection optimization. The method presented provided the theoretic basis for the reliability robust design of the rotor system. A numerical example demonstrated that the proposed method is effective.

Frequency Reliability Sensitivity and Robust Design of the Multispan Rotor System

The multispan rotor system(H858 compressor) is studied.The natural frequencies are obtained in the condition of bending vibration using finite element software(MSC.PatranNastran).With the criterion that the absolute value of the difference between the natural frequency and forcing frequency,the failure mode are defined,then the equations of the frequency reliability and the related frequency reliability sensitivity with respect to mean values and variances are mathematically expressed.And then the reliability-based robust design of structure is studied based on the reliability-based optimization model,and the numerical method of frequency reliability-based robust design is proposed.The frequency reliability sensitivity and reliability-based robust design for the multispan rotor system are extensively discussed by the above mentioned theory,which provide more theoretic evidence for the rotor system design in practical operation.

Frequency Reliability Sensitivity for Dynamic Structural Systems#

Parameter uncertainty of structural systems is inherent in most engineering problems. Therefore, reliability analysis of uncertain structural systems is of great significance, and frequency reliability analysis is important to uncertain vibration structure systems. Based on the frequency reliability theory, this article introduces an approach to calculate the reliability of a mechanical structure under dynamic excitation. With the criterion that the absolute value of the difference between the natural frequency and forcing frequency, the reliability mode and the safety probability of random systems are defined, and then the frequency reliability sensitivity analysis method is presented. The structure is supposed to fail if the frequency of the external force is within a predefined distance of structural resonant frequencies. The frequency reliability sensitivity analysis method for resonant problem of dynamic structural systems reliability is proposed by using the random perturbation technique, the reliability theory, and sensitivity approach. The formulas of quasi-failure probability sensitivity are derived when random variables are normally distributed. The reliability is evaluated, and its sensitivity to mean values, variances, and covariances is mathematically expressed, then the efficiency and accuracy of the proposed method are demonstrated by a numerical example.