Research On Viscoelastic Damping Control Technique For Vibration And Acoustic Radiation Of Shell Structure

Viscoelastic damping structure has such merit as good damping property, good applicability and wide band of vibration reduction, and is widely used in the field of vibration and acoustic radiation for military and civil industry of large ships, warship and torpedoes. But it takes the new problem of mass addition with damping material. And the present theoretical of control technique needs further development. This article studies the application of viscoelastic damping control technique in vibration and acoustic radiation, which represents some theoretical value and practical engineering applications.The finite element iteration procedure is chosen to simulate the viscoelastic structure according to the characteristics that the constitutive relation of viscoelastic material is represented by complex and changes with frequency. And the method is certified by the model of viscoelastic sandwich beam. Then the ring-stiffened conical shell with substrates is analyzed with this method. The effect of different laying method to structure vibration characteristics is studied, which obtains the best location of viscoelastic material on structure base.More damping material takes the increase of structure mass in practical engineering, so the amount of damping material is controlled. On the premise of invariable damping material dosage, the damping is optimized in order to maximize material utilization and best damping effect. Firstly, the topology optimization method of constrained damping structure based on optimum criterion method is studied,and the topology optimization program is written. Then the layout of constrained damping material on constrained layer damping cylindrical shell is optimized, which obtains the best laying method of material. Secondly, the thickness of damping layer and constrained layer is optimized using size optimization,which obtains the best thickness.The underwater acoustic radiation of viscoelastic structure is an important research direction recently. The underwater vibration and acoustic radiation of structure is computed through the finite element method and boundary element method in this article. The intrinsic modes and coupled modes with water of ring-stiffened conical shell are computed, and the radiated sound field under the water is analyzed. Then the effect of damping on acoustic radiation is analyzed after laying viscoelastic damping on structure. And impact to acoustic of structure such as thickness of damping and the location of the damping is analyzed, which obtains some general rules.The conclusions of this article provide certain guiding significance on the laying method of structure vibration and acoustic radiation control, and offer the beneficial reference for the choice and layout of viscoelastic damping material.