Experimental Study And Test System Development Of Vibration Characteristics Of Thin Cylindrical Shells

The thin cylindrical shell structure is widely used in engineering practice,such as the drum of aero-engine,the pressure pipeline of oil transportation,the outer shell of the submarine,etc.In different engineering structures,the cylindrical shell is in different restraint states.During the working process,the cylindrical shell is subjected to extremely severe external loads,and the vibration state is relatively complicated.In most cases,structural damage or fatigue damage may occur,and the above two situations may easily cause the machine working stability to be lowered.The equipment will be destroyed when it works in a long time.Vibration test has always been an indispensable part of dynamic analysis.Commercial vibration testing and analysis software can be used for routine vibration testing and analysis,but it cannot be redeveloped.There is no obvious advantage in researching new vibration testing methods.Therefore,the independent development of new test systems is of great significance for studying the vibration characteristics of thin cylindrical shells.In this paper,the thin cylindrical shell structure with different constraints is taken as the research object.The vibration characteristics of the thin cylindrical shell structure are studied by experimental test methods,including modal parameter test and nonlinear response test,and a set of thin cylindrical shell modal characteristic test system is developed.This article mainly completes the following aspects:First,explain the modal test principle applied in the experimental modal analysis of thin cylindrical shells,including the basic theory of modal test and the basic theory of modal parameter identification.The finite element method and the experimental method(hammer method and exciter method)commonly used in modal analysis are compared,and the steps,advantages and disadvantages of the two methods are summarized.Taking the thin cylindrical shell with free ends as an example,the finite element software modal analysis and the hammering modal test are carried out simultaneously,and the two results are compared.Second,design the whole-circle constrained thin cylindrical shell structure,build a modal parameter test system for the constrained thin cylindrical shell for the whole week,and calibrate the test system from the perspective of engineering application to ensure the accuracy of the experimental data collected.The modal parameter test new method is used to test the natural frequency,mode shape and modal damping of the constrained thin-walled cylindrical shell.The test principle,test flow and data processing process are described in detail,and the test results are compared with the LMS test results.The results show the correctness of the test method in this paper.Third,the design point constrains the thin cylindrical shell structure,and builds a pointconstrained thin-walled cylindrical shell nonlinear response test system.The point constraint test system is described in detail from the aspects of test equipment,test principle and test system calibration.The experimental results were compared with references.The effects of support stiffness,number of supports and thickness-to-diameter ratio on the nonlinear response of point-constrained thin cylindrical shells are studied.Last,based on Lab VIEW,develop the thin cylindrical shell modal parameter test system,describe the development tools and development principles of the test system,explain the requirements analysis and overall design process in the test system design process,and explain the test system workflow.Explain the development process,software architecture and usage requirements of the system's main module and modal parameter test module.