The Investigation Of Vibration And Acoustic Radiation Characteristics In Pipe Structure

Based on the pipe structure widely used in the military equipment and civilian establishments, particular attention are concentrated on both the dynamic responses of running piping under the action of moving loads and the acoustic radiation characteristics of typical water filled pipe caused by the exterior motivation in this paper.In the first part of paper, beam with moving mass model is used to simulate running piping. With taking into account the gravity of the beam, the gravity and velocity of the moving mass, the dynamic responses of simply supported beams under the action of moving loads are investigated in this paper. The Galerkin method has been used to discretize the beam model and formulate the corresponding dynamic equations of the system. For a beam with constant moving velocities, the numerical results, in contrast to the works by formerly investigators, have demonstrated the accuracy and validity of the proposed numerical program. Moreover, the dynamic responses of beam system with constant or accelerated velocity moving mass are obtained via numerical calculations. The effects of velocity or acceleration of moving mass on the dynamic responses are further discussed. The acquired results show that there are distinct differences between two beam models: with constant moving velocity and accelerated moving velocity.In the second part of paper, Mechanics of Vibrations, Fluid mechanics, Finite Element Method (FEM) and Boundary Element Method (BEM) and computer imitation are applied to analyze the dynamic responses of pipe structure, and the structural vibro-acoustic radiation mechanism of coupling system. Vibrations of an excited water filled straight pipe and U-shape pipe and their radiation field are investigated by using software ANSYS and acoustic code SYSNOISE. The normal displacement which is stimulated by node force on the coupling surface is calculated in ANSYS firstly. Then inherent modes are obtained and the mesh element information and normal displacement of the outer surface are drawn out and set as the boundary conditions of the BEM model. Based on this, the surface sound pressure and outside sound field are computed. For the pipe under consideration, it is shown that the thickness of pipe and coupling mode may influence on vibro-acoustic radiation to some extent. The study gives a convenient and effective way for noise control and optimum design of typical pipes in engineering.