Research On Automatic Parameterized Finite Element Modeling And Simulation Technology Of Aircraft Hydraulic Pipelines

With the lightening requirements to the new generation of aircraft and the increase in the working pressure of the hydraulic system,the vibration problem of aviation hydraulic pipelines has become more significant,which has a significant impact on the reliability and safety of the aircraft.Vibration analysis is of great significance.At present,many scholars have carried out vibration analysis and parametric modeling research for the specific hydraulic pipeline objects.However,the number of pipelines in aircraft hydraulic system is large and there are many types of accessories,so it is difficult for conventional finite element analysis methods to carry out a large number of hydraulic pipeline analysis and verification work.In view of the above problems,this paper studies the automatic realization method of the parametric modeling of the aircraft hydraulic branch pipelines.The parametric finite element automatic modeling,solution analysis and post-processing macro files of the hydraulic branch pipeline of aircraft are written by ANSYS parameter design language(APDL)and CFX command language(CCL).Based on this,the parameterized finite element modeling,solution analysis and post-processing of simulation results of different aircraft hydraulic pipelines are realized.The process of finite element modeling and analysis for hydraulic pipelines is simplified and the efficiency of pipeline design is improved.The specific research content and results of this paper are as follows:(1)Research on simplification,meshing and contact setting methods of hydraulic pipeline components.Based on the existing hydraulic pipeline component models,this paper summarizes and discusses the reasonable simplification method,meshing method and contact setting method of different pipeline components on the hydraulic pipeline,such as pipe clamps,clamps,joints and brackets.etc(2)Research on the automatic realization method of parametric finite element modeling of hydraulic pipelines.Aiming at the problems of multi-type support space positioning,pipeline space orientation and pipeline connection,the methods of separate coordinate positioning and segmented axis fitting are used to study hydraulic pipeline support modeling and conduit and joint modeling technology.Based on the hydraulic pipeline component modeling method,the finite element modeling method macro file library and assembly macro file of each component of the hydraulic pipeline are compiled using APDL modeling language,and the key geometric dimensions of the model are parameterized to realize the finite Parameterization of meta-models and universality of model macro files.Using the method of macro calling and conditional loop to call each component modeling and assembly macro file to realize the automation of the finite element modeling process of the hydraulic pipeline.(3)Research on hydraulic pipeline simulation technology.Based on the fluid structure coupling method,the influence of pressure as prestress on the modal frequency of a series hydraulic pipelines is studied.Through theoretical derivation,the calculation method of equivalent density of space pipeline and the effectiveness of modal frequency extraction range of random vibration spectrum analysis are studied.The static pressure value and the steady-state analysis result are used as the initial boundary conditions of the two-way fluidstructure coupling transient analysis to study the influence of the two on the vibration response of the hydraulic pipeline under the pulsating pressure load.This part of the research work lays the foundation for embedding the pipeline fluid-structure coupling simulation analysis function into the software platform to realize automatic operation in the background.(4)Research on modularization and automation of hydraulic pipeline finite element analysis.Based on the fluid-structure coupling theory,fluid mechanics knowledge and vibration analysis theory,use APDL language to compile the modular analysis macro file of fluidstructure coupling modal analysis and random vibration analysis under fundamental excitation of aircraft engines.Then,using APDL language and CCL language,a batch file for the transient analysis of the bidirectional fluid-structure coupling of the branch pipeline under the pulsating pressure load is compiled,which realized the modularization and automation of the above analysis process.Finally,the parametric finite element automatic modeling and modular finite element automatic analysis of a branch of the hydraulic pipeline are carried out to verify the validity of the research content in this paper.