Research Of Vibration Reduction Of Fluid-conveying Pipes Based On The Receptance Method

Fluid-conveying piping system is an important part of aerospace,shipbuilding,automobile and other industrial fields.Vibrations of pipe structure may cause the system instability and damaged or influence the working environment of other equipment.It is of great significance that research the vibration characteristics of fluid-conveying pipes and the method of vibration reduction for pipes.In this paper,the mathematical models of fluid-conveying pipes which have complex distribution in space are established based on the receptance method,and it is verified by experiment.On this basis,vibration reduction method of fluid-conveying pipes is put forward.First,linear motion differential equation of fluid-conveying straight pipe is derived and the receptance matrix of pipe is obtained.Fluid-conveying pipes with arbitrarily space distribution can be discreted by straight pipe unit.For piping support,the technique dealing with elastic support containing damping and fixed support is put forward.Therefore the receptance matrix of complex fluid-conveying pipes are obtained.Then vibration experimental platform of complex fluid-conveying pipes is designed.The dynamic stiffness data of rubber support obtained through experiment are used in the mathematical models to calculate the first four natural frequencies of complex fluid-conveying pipes which have minor error compared with experiment result.It is verified that the mathematical models can estimate vibration characteristics of fluid-conveying pipes effectively by comparing calculating frequency response functions with experimental frequency response functions.On this basis,the influence of velocity on natural frequencies of complex fluid-conveying pipes is analyzed.`Finally,focusing on the situation of piping vibration cased by external incentive,a piping vibration reduction technique is proposed using zero assignment method of passive structure modification.One or more zeros can be assigned on target freedom by attaching point mass,grounding damping and grounding spring to appropriate freedom.On this basis,dynamic vibration absorber used in piping systems is designed.The receptance matrix of dynamic vibration absorber coupling with fluid-conveying pipes is derived to research the characteristic of vibration reduction.The piping dynamic vibration absorber is manufactured with 3D printing technology and its effect is verfied by experiment.The influence of design parameters of dynamic vibration absorber on vibration reduction is analyzed by calculation.The numerical calculation method proposed by this paper can provide information for the vibration reduction research of fluid-conveying pipes.