Model Updating Of Nuclear Power Valve Pipeline System Based On Response Surface And Bat Algorithm Method

As an important part of nuclear power plants,the seismic design and analysis of valve piping systems are necessary to ensure the safe operation of nuclear power plants during earthquakes.At present,finite element analysis method is the main method for seismic design of nuclear power valve piping systems,but there is often a certain deviation between the model and the actual structure.The finite element model correction method,which uses test data to correct the unknown structural parameters in the model,is an effective means to improve the relevance of the actual structure,however,little research has been done on how to realize the finite element model correction of nuclear power valve piping systems with high efficiency and accuracy.Based on this,a finite element model correction method combining response surface method and bat algorithm is proposed with the measured intrinsic frequency as the objective function.The response surface model can replace the implicit nonlinear relationship to avoid repeated calls to the finite element model during the correction iteration;the bat algorithm solves the problem of falling into the local optimum by narrowing the range of the search and enhancing the local search,which can efficiently complete the iterative parameter search.Then,the feasibility and effectiveness of the proposed method are verified through numerical simulations and experiments to provide guidance for its practical application.The main conclusions of the paper are as follows:(1)An efficient and high-precision finite element model correction method for nuclear power valve systems is proposed.The method fits the implicit nonlinear relationship between the structural parameters of the valve system s and the mode through the response surface model,avoiding the sensitivity analysis and derivative derivation of the vibration control equation of the valve systems,and the iterative correction process is realized based on the bat algorithm,which is simple to set the parameters and not easy to fall into the local optimum,and can efficiently realize the parameter search,so as to realize the efficient correction of the finite element model of the nuclear power valve systems and improve its correlation with the actual structure.The correlation with the actual structure is improved.(2)The feasibility of the proposed method is verified through numerical simulations by introducing known errors in six-degree-of-freedom spring oscillator model.Four combinations of parameters to be corrected are set in the simulation to verify the feasibility of the proposed method when the parameter types are different and the number of parameters deviates from the available modal order.The numerical simulation results show that the response sur face can be more accurate when the parameters to be corrected are of the same nature and the number of parameters is less than or equal to the number of measured modes,and the correction process should avoid selecting combinations with different parameter types.(3)A concentrated mass model highly correlated with the actual nuclear power valve piping system was established to correct the structural parameters related to the bracket and valve,and the feasibility of the proposed method in engineering practice was demonstrated.The model has more unknown structural parameters,and too many response surface model coefficients are fitted,resulting in low computational efficiency.Therefore,the adaptive response surface method is introduced to reasonably simplify the model cross terms and improve the computational efficiency.The modified modal parameter values are closer to the measured values than those of the existing methods,which proves the reliability of the method in the modification of the actual nucl ear power valve system model.The research results of this paper can efficiently and accurately correct the model of nuclear power valve systems and reduce the error between the model and the actual structure,which is important to improve the credibility of the finite element calculation results of valve systems seismic response and is an important guarantee for the reliability of the in-service pipeline seismic performance reassessment results.In addition,the method has the potential to realize the real-time virtual-real mapping of its dynamical model,which can support the implementation of digital twin technology for nuclear power valve piping systems.