Research On Pipeline Vibration Reduction Based On New Variable Stiffness Tuned Mass Damper

Pipeline system is known as the "blood vessel" in industrial production and is widely used in petrochemical,aerospace,marine engineering and other industrial fields;At the same time,the pipeline system is often seen in urban water supply,central heating and other facilities related to national life.Due to the excitation of external factors such as mechanical equipment connected to the pipeline,the pipeline system often produces vibration,which will lead to equipment shutdown and even major accidents endangering the safety of people’s lives and property.Therefore,the vibration control of pipeline system is the key to ensure its safe and stable operation.As a kind of structural vibration control device,tuned mass damper has its unique advantages when applied to the vibration reduction of pipeline system.However,the vibration reduction frequency of the traditional tuned mass damper is single and fixed,and the natural frequency of the pipeline system often changes slightly with the theoretical calculation value due to manufacturing errors,field conditions and other factors,which will lead to the decline of vibration control effect.Therefore,this paper solves the above problems from two aspects: developing the dynamic modeling of pipeline system to accurately solve its natural frequency and designing a variable frequency tuned mass damper.The main work of this paper is summarized as follows:1.Carry out the dynamic modeling and natural frequency solution of U-shaped pipeline based on the global modal method: Accurately understanding the natural frequency of pipeline system is the premise of vibration control.For the U-shaped pipeline built in this paper,the global modal coordinate system is established according to its structure.Based on the relevant theory of Euler Bernoulli beam model,the global modal function of U-shaped pipeline is derived by using the global modal method,and its boundary conditions and matching conditions are substituted into it to further obtain the frequency equation H(ω)ψ=0.By solving the frequency equation,the natural frequency of U-shaped pipeline is finally obtained.The accuracy of this method is verified by ANSYS finite element simulation.2.A new type of variable stiffness tuned mass damper applied to vibration reduction of pipeline system is proposed.In order to make up for the deficiency of single fixed vibration reduction frequency of traditional tuned mass damper,a new type of variable stiffness tuned mass damper is proposed based on beam structure.Its overall design is a detachable structure,which can be flexibly disassembled and assembled on the pipeline.The new variable stiffness tuned mass damper has the characteristics of variable stiffness at different angles.The variation range of its stiffness is calculated by means of finite element simulation between 7.541N/mm and 52.175N/mm,and the stiffness measurement experiment is carried out to verify the accuracy of the stiffness of its 3D printed product.3.In order to verify the vibration control effect of the new variable stiffness tuned mass damper on U-shaped pipeline,a vibration reduction test-bed of U-shaped pipeline system is built in this paper.Before the vibration reduction experiment,in order to accurately grasp the natural frequency of U-shaped pipeline in the experimental site,based on the principle of fiber Bragg grating sensing,the natural frequency of U-shaped pipeline is actually measured by fiber Bragg grating sensor.Then,the scheme and steps of vibration reduction experiment are formulated,and the vibration reduction experiments in empty pipe state and liquid filled state are carried out respectively.The experimental results show that the new variable stiffness tuned mass damper has a good vibration control effect on the U-shaped pipeline,and when the natural frequency of the U-shaped pipeline changes slightly,the better vibration reduction effect can be obtained by adjusting the installation angle of the variable stiffness inner ring to change its vibration reduction frequency,which has engineering application value and significance.