Time-dependent Reliability Analysis And Optimization Of Circulating Pump Gearbox Transmission System

The nuclear power circulation pump gearbox,as one of the key components of nuclear power equipment,has advantages such as high transmission power,long service life,and reliable operation safety.However,the late start of domestic nuclear power equipment technology,coupled with its own design and manufacturing technology is very complex,resulting in nuclear power circulation pump gearbox reliability and safety is significantly lower than the leading foreign level.Therefore,this thesis analyzes and studies the reliability of the nuclear power circulating pump gearbox transmission system.The main contents and results are as follows:(1)Static reliability analysis of circulating pump gearbox transmission system.The structure of the circulating pump gearbox system is complex and the working conditions are changeable.The thesis studies the static reliability method based on the surrogate model.Using the Kriging model to approximate the system modeling,a new learning function is proposed by combining the probability density and spatial location information of sample points and the stopping criterion is improved.Meanwhile,in order to solve the problem of correlation between failure modes,Multiple Response Gaussian Process(MRGP)was used to establish a multi-failure mode correlation reliability analysis method and applied to the reliability analysis of the circulating pump gearbox transmission system.Then,compared with Monte Carlo Simulation,the effectiveness of the proposed method is verified.(2)Time-dependent reliability analysis and sensitivity analysis of circulating pump gearbox transmission system.In the operation of circulation pump gearbox,the load and material properties often change with time,therefore,the time-dependent characteristic is more obvious.Based on the static reliability analysis,this thesis analyzes the timedependent reliability of the circulating pump gearbox transmission system.During the operation of circulating pump gearbox,there are various factors that cause the gears to fail.In the thesis,the global sensitivity analysis of the circulating pump gearbox transmission system is carried out jointly with the time-dependent reliability analysis model to obtain the uncertainty contribution and ranking of the input variables to the failure probability.(3)Uncertainty optimization design of circulating pump gearbox transmission system.Circulation pump gearbox occupy large space,which is not conducive to manufacturing and maintenance.Under the premise of ensuring its quality reliability and safety,reducing the volume as much as possible has been the goal pursued in practical engineering.Based on this,the thesis uses the gearbox volume as the objective function and the interval non-probability model to describe the uncertainty of parameters for the uncertainty optimization design of the nuclear power circulation pump gearbox.The traditional uncertainty optimization problem is usually a double-layer nested cycle with low efficiency.Therefore,an improved interval analysis method based on Kriging model is proposed instead of inner loop optimization in the thesis.This method has good results for systems with complex structure and high degree of nonlinearity.The proposed method is applied to the uncertainty optimization of circulating pump gearbox and compared with the interval optimization method of double-layer nested cycles to verify the effectiveness of the method.