Reliability Model of Gear With Correlated Failure Modes Based on Joint Distribution

2014 ◽  
Author(s):  
Lai Yue-Hua ◽  
Dong Hai-Ping ◽  
Yi Xiao-Jian ◽  
Ding Juan ◽  
Lei Hua-Jin
Keyword(s):  
Joint Distribution ◽  
Failure Modes ◽  
Physical Models ◽  
Total Probability ◽  
Traditional Model ◽  
Reliability Model ◽  
Interference Theory ◽  
Calculation Results ◽  
Set Up ◽  
Total Probability Theorem

In this paper, a precise reliability model for gear with correlated failure modes is presented. Firstly, physical models of stress and strength are set up against two main failure modes of a gear respectively. Then, the corresponding performance functions to the two failure modes are obtained according to stress-strength interference theory regarding randomness of variables in physical models of stress and strength. Furthermore, joint distribution of the two performance functions is deduced by Total Probability Theorem considering the correlation of random variables. So, reliability of a gear with correlated failure modes can be computed based on the joint distribution. Finally, an example is given and in this example the precise reliability model based on joint distribution and the traditional reliability model without considering the correlation of failure modes, are respectively adopted to calculate reliability of a gear. The calculation results are compared with that by Monte Carlo simulation and the compared results show that the gear’s reliability obtained by considering correlation of failure modes based on joint distribution is more accurate than that by the traditional model without considering the correlation of failure modes.

Lightweight Analysis of Torsion Spring Based on Reliability Constraint in Multi-Failure Modes

2011 ◽  
Vol 308-310 ◽  
pp. 494-498
Author(s):  
Mei Wang ◽  
Guo Ding Chen ◽  
Yong Xiao
Keyword(s):  
Optimization Design ◽  
Failure Modes ◽  
Optimization Method ◽  
Strength Distribution ◽  
Operating Conditions ◽  
Reliability Model ◽  
Constraint Condition ◽  
Interference Theory ◽  
Torsion Spring ◽  
Reliability Constraint

The generalized stress and strength distribution interference theory is introduced to establish the reliability model of torsion spring in multi-failure modes. Using it as constraint condition, the lightweight optimization model of torsion spring based on reliability constraint in multi-failure modes is presented. And then an optimization design for a given structure of torsion spring is made to use the theoretical model under operating conditions and the reliability constraint. The weight of the opti-mized torsion spring is lighter than that of non-optimization. This verified the validity of the opti-mization method. The optimization method may contribution to design of aerospace equipments which demand strictly in weight.

Concrete Fatigue Life Characteristics of the Different Survival Rates in the Lateral Pressure Conditions

2012 ◽  
Vol 600 ◽  
pp. 250-255
Author(s):  
Qiang Cai ◽  
Ji Ming Kong ◽  
Ze Fu Chen
Keyword(s):  
Fatigue Life ◽  
Life Stress ◽  
Failure Modes ◽  
Survival Curve ◽  
Survival Rates ◽  
Life Distribution ◽  
Fatigue Design ◽  
Set Up ◽  
Fatigue Equation ◽  
Two Parameter

Under cyclic loading of concrete structures, fatigue failure is the main failure modes of fatigue, which has become the fatigue design of concrete structure must be considered, then the concrete fatigue studies must clarify the fatigue life of concrete under different survival curve S-N curve. Based on the statistics of the two parameter Weibull distribution theory, obtain the concrete under different survival rates of fatigue life distribution, namely to improve survival, reduce the fatigue life; stress level is reduced, the fatigue life is increased; and has set up more than 50% under different survival rates of concrete fatigue equation.

Ironmaking Process Parameter Analysis and Optimization for the Blast Furnace

2009 ◽  
Vol 620-622 ◽  
pp. 21-24
Author(s):  
Shuang Ping Yang ◽  
Yong Hui Song ◽  
Liu Hua Xin
Keyword(s):  
Optimal Operation ◽  
Partial Least Square ◽  
Least Square ◽  
Parameter Analysis ◽  
Partial Least Square Regression ◽  
Evaluation Indicator ◽  
Least Square Regression ◽  
Calculation Results ◽  
Set Up ◽  
Reasonable Description

With practical data of the BF ironmaking from Jiuquan Iron&Steel Cooperation Ltd. (JISC), taking the quality of pig iron as evaluation indicator, mathematical models based on the least square regression and partial least square regression were set up respectively by co-relation analysis of feeding-to-product interval of the BF processing. The calculation results showed that the reasonable description can be obtained by the partial least square regression model; and 10 of 29 parameters with obvious impact on the BF operation were listed accordingly. Meanwhile, an optimal group of parameters was found by genetic algorism calculation method. The optimal index of the group was 99.13％. This study is beneficial to the improvement of feeding adjustment and optimal operation of BF ironmaking.

scholarly journals Comparative analysis of cycloid pump based on CFD and fluid structure interactions

2020 ◽  
Vol 12 (11) ◽  
pp. 168781402097353
Author(s):  
Wang Yanhua ◽  
Huang Longlong ◽  
Liu Yong ◽  
Xu Jingsong
Keyword(s):  
Model Building ◽  
Contact Point ◽  
Great Influence ◽  
Test Results ◽  
Fluid Structure Interactions ◽  
Fluid Structure ◽  
Mean Values ◽  
Calculation Results ◽  
Different Temperatures ◽  
Set Up

At present, in the aspect of numerical simulation of cycloid pump, most studies focused on CFD (Computational Fluid Dynamics) in analyzing the pump performance under different service conditions (such as speed, temperature, etc.). The characteristics of the pump under FSI (Fluid Solid Interaction) have not been considered yet. By means of the dynamic mesh technique in the rotating domain, the fluid structure coupling interface is set up on a cycloidal pump model building in COMSOL. The simulation results obtained by applying CFD and FSI are improved by experimental verification. The results show that: (1) the average flow rate of FSI simulation is closer to the test results, and the mean values of CFD and FSI pressure are closer to the actual outlet boundary settings; (2) by comparing the velocity and pressure of rotation region of CFD and FSI at different temperatures, it is concluded that the pressure CFD calculated in the region is more than FSI, and the velocity CFD calculated is less than FSI; (3) by comparing the pressure distribution at some contact point of the fluid structure coupling interface, it is concluded that the fluctuation value of the pressure of CFD with time is greater than that of FSI. Through the comparison, it is found that the coupling has a great influence on the calculation results. The FSI analysis of the pump makes the analysis results more real and more conducive to the analysis of the flow field and rotor dynamics characteristics of the pump.

A Method for the Calculation of the Tip Clearance Flow Effects in Axial Flow Compressors: Part II — Calculation Procedure

1993 ◽  
Author(s):  
I. K. Nikolos ◽  
D. I. Douvikas ◽  
K. D. Papailiou
Keyword(s):  
Axial Flow ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Vorticity Distribution ◽  
Clearance Flow ◽  
Calculation Results ◽  
Flow Effects ◽  
Set Up ◽  
Induced Velocity ◽  
Theoretical Procedure

An algorithm was set up for the implementation of the tip clearance models, described in Part I, in a secondary flow calculation method. A complete theoretical procedure was, thus, developed, which calculates the circumferentially averaged flow quantities and their radial variation due to the tip clearance effects. The calculation takes place in successive planes, where a Poisson equation is solved in order to provide the kinematic field. The self induced velocity is used for the positioning of the leakage vortex and a diffusion model is adopted for the vorticity distribution. The calculated pressure deficit due to the vortex presence is used, through an iterative procedure, in order to modify the pressure difference in the tip region. The method of implementation and the corresponding algorithm are described in this part of the paper and calculation results are compared to experimental ones for cascades and single rotors. The agreement between theory and experiment is good.

Time-Dependent Reliability Analysis of Vibratory Systems With Random Parameters

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Zissimos P. Mourelatos ◽  
Monica Majcher ◽  
Vasileios Geroulas
Keyword(s):  
Large Scale ◽  
Probability Of Failure ◽  
Time Dependent ◽  
Total Probability ◽  
Conditional Probabilities ◽  
Random Parameters ◽  
Random Vibrations ◽  
Input Parameters ◽  
Total Probability Theorem ◽  
Dependent Probability

The field of random vibrations of large-scale systems with millions of degrees-of-freedom (DOF) is of significant importance in many engineering disciplines. In this paper, we propose a method to calculate the time-dependent reliability of linear vibratory systems with random parameters excited by nonstationary Gaussian processes. The approach combines principles of random vibrations, the total probability theorem, and recent advances in time-dependent reliability using an integral equation involving the upcrossing and joint upcrossing rates. A space-filling design, such as optimal symmetric Latin hypercube (OSLH) sampling, is first used to sample the input parameter space. For each design point, the corresponding conditional time-dependent probability of failure is calculated efficiently using random vibrations principles to obtain the statistics of the output process and an efficient numerical estimation of the upcrossing and joint upcrossing rates. A time-dependent metamodel is then created between the input parameters and the output conditional probabilities allowing us to estimate the conditional probabilities for any set of input parameters. The total probability theorem is finally applied to calculate the time-dependent probability of failure. The proposed method is demonstrated using a vibratory beam example.

The Application Study of Accumulator Used in Hydraulic System of 20MN Fast Forging Machine

2011 ◽  
Vol 80-81 ◽  
pp. 870-874 ◽  
Author(s):  
Min Qiang Dai ◽  
Sheng Dun Zhao ◽  
Xiao Mei Yuan
Keyword(s):  
Energy Conservation ◽  
Hydraulic System ◽  
Pressure Pulsation ◽  
Test System ◽  
Hydraulic Shock ◽  
Application Study ◽  
Calculation Results ◽  
Set Up ◽  
Forging Press ◽  
Made In

Based on the description of 20MN fast forging press hydraulic system, the paper analyzed the possibility of energy conservation which the accumulator made in the fast forging machine system. When accumulator was used in fast forging machine, then analyzed the calculation results, and the energy conservation program of fast forging machine energy accumulator was evaluated briefly. The test system was set up on 20MN fast forging machine, and the paper researched the application of accumulator in fast forging press hydraulic system on absorbing hydraulic shock and eliminating pressure pulsation.

scholarly journals Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jie Hong ◽  
Tianrang Li ◽  
Zhichao Liang ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Element Model ◽  
Physical Parameters ◽  
Test Rig ◽  
Calculation Results ◽  
Rotor Support ◽  
Blade Tip ◽  
Set Up ◽  
The Impact

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

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