Research On Vibration Prediction Method Of Launch Vehicles And Development Of Software

The excitation environment faced by launch vehicles in flight is complex and changeable,which will lead to the failure of rocket structure and internal equipment.The excitation is random broadband excitation.The frequency range of excitation covers low,medium and high frequencies,therefore,different methods need to be adopted in the analysis,but those methods are free and dispersed,and lack of effective integration.In response to this question,this paper applied PyQt5 developed a environment prediction analysis system based on simulation and engineering methods,this analysis system will integrate engineering prediction method represented by extrapolation with theoretical prediction methods represented by the finite element method(FEM)suitable for low frequency vibration、finite element-statistic energy analysis(FE-SEA)apply to mid-frequency vibration and statistic energy analysis(SEA)suitable for high frequency vibration,consequently improve environmental predictive power.From the engineering prediction mode based on ground test and experience,it has been transformed into the prediction mode of parallel development of theoretical simulation prediction and engineering prediction.From the previous decentralized prediction mode,the transformation to the system integration mode.The specific work content is as follows:1.The prediction method of vibration response and its application process are summarized.Including engineering prediction method represented by extrapolation;FEM,boundary element method(BEM),finite element and boundary element analysis(FEA-BEA)and pseudoexcitation method(PEM)are suitable for low frequency conditions.FE-SEA and energy distribution analysis(EDA)under mid-frequency condition;SEA method is suitable for high frequency condition,and verified by examples.2.The operation window of the software platform can be designed by Qt Designer to realize interface interaction with users.3.Python language is adopted to realize the function of the software platform,so that users can predict vibration response by operating in the software platform.The main process of development is divided into four aspects:1)In the low frequency analysis section,MSC PATRAN/NASTRAN was secondary developed by PCL.When the users set parameters and boundary conditions in the operation interface,the system can automatically call MSC PATRAN/NASTRAN for random vibration analysis,and realize parametric modeling and process simulation analysis2)In the mid-frequency analysis section,the interface between the software system and VA One is established.The rocket model can be built and analyzed using FE-SEA by VA One.3)In the high frequency analysis section,the rocket model is divided into subsections.In analysis,this platform will directly call SEA method written by MATLAB for calculation,so the application of SEA method in software platform is realized.