Study On The Dynamic Mechanical Behavior Of Flexible Rotating Beam Under Axial Compression Constrained In A Horizontal Pipe

The flexible rotating beam in the horizontal pipe is an important structure in chemical process machinery and petroleum machinery,and it performs rotary motion in the wall filled with fluid.It withstands complex loads such as pulling,pressing,bending,and twisting.The flexible rotating beam makes multi-directional collision contact with the bore hole wall.At the same time,the hollow rotating slender beam and the outer annulus have fluid action,forming a complex nonlinear solid-liquid coupling system.The vibration of the axially compressed flexible rotating beam in the horizontal pipe includes three kinds of vibrations axial vibration,torsional vibration and lateral vibration.In complex working conditions,the three vibrations will be coupled or fully coupled,which considers the coupling of various complicated conditions.The safety of the vibration of the flexible rotating beam is very great.Therefore,the fulll-coupled vibration of the three kinds of vibration modes under the complicated conditions of the flexible rotating beam in the horizontal tube is carried out.The structural optimization design,process parameter selection and optimization of the flexible rotating beam are meaningful.The complex load is simplified into the axially compressed flexible rotating beam before the quantitative analysis by considering the complexity of the coupled vibration model under complex conditions.Based on the theory of rotating shell,the dynamic equation of the axially compressed flexible rotating beam is established.Then the Galerkin method is used to discretize the partial differential equation of motion.The nonlinear governing equation of the axially compressed flexible rotating beam in the horizontal tube is obtained.Then the multi-scale method is used to obtain the average equation of motion,and dimensionlessly processed.The dynamic response of the flexible rotating beam in complex environment is analyzed.The axial excitation,torsional excitation and lateral excitation are applied to the flexible rotating beam.The influence law of the dynamic behavior of vibration is given.The finite element method has been applied to the analysis of the dynamic behavior mechanism of flexible rotating beams for several decades,but most of them are still limited to straight beam elements and plane circular beam elements.For the analysis of the dynamic characteristics of flexible rotating beams in horizontal tubes under three-dimensional Cartesian coordinates,the calculation accuracy of these methods is low and it is difficult to meet the requirements.The study on the dynamic behavior of flexible rotating beams in complex environments using space beam elements is still not sufficient.The influence of the excitation source on the dynamic behavior of the flexible rotating beam is obtained based on the qualitative analysis.Then taking account to the dimensionless process and the similarity theory,the contact between the flexible beam and the pipe wall,the fluid action inside and outside the flexible beam,the axial and torsional excitation,the complex load on the bottom of the flexible beam,the dynamic model of the axially compressed flexible rotating beam in the horizontal pipe is established in coupled zone based on the extended Hamilton’s rule.The finite element method is used to discretize it into three-dimensional space units to obtain the equation of motion of the system.The Newmark method is used to numerically integrate the differential equations.The Gaussian quadrature method is applied to optimize the integral process.And the successive over relaxation method is used as the iterative convergence criterion to obtain the numerical solution of the equation of motion,and the six degrees of freedom of each unit of the flexible rotating beam are finally obtained.The influence of axial excitation and torsional excitation on the dynamic behavior of the flexible rotating beam in the horizontal tube is studied based on the established numerical model.Finally the dynamic characteristics of the axially compressed flexible rotating beam in the horizontal tube are obtained.Then,a dynamic behavior test system for axially compressed flexible rotating beam is developed based on the results of qualitative analysis,quantitative analysis and the similarity theory.It can simulate the fluid interaction inside and outside the pipe,the rubbing and torsion of the flexible beam,axial and torsional excitation source and loading.The three displacement of the horizontal rotating flexible rotating beam,the rotation speed and the axial force at the beginning and the end are measured.Finally,verification test of numerical simulation results is carried out based on the qualitative analysis,quantitative analysis results and the test system.By changing the torsional excitation and the axial excitation(the rotation speed of the top of the flexible rotating beam and the initial axial pressure of the top),the variation of the dynamic behavior of the axially compressed flexible rotating beam in the horizontal tube under different excitation sources is analyzed.It provides scientific guidance and theoretical support for the selection of key parameters in the flexible beam working process.