Research On The Vibro-acoustic Properties Of Curved Stiffened Plate Structure

The reinforced structure is an economical and convenient way, which can greatly improve the rigidity and bearing capacity of the structure. It has been widely used in aerospace, shipbuilding, automobile, large engineering equipment. However, the reinforcement will directly affect the sound and vibration properties of the structure, and the acoustic properties of the structure will directly affect the overall performance of the equipment. Therefore, it is important to study the vibration and acoustic radiation properties of stiffened structures. The curved stiffened plate as a new form of reinforced structure, with the advantage that the traditional reinforcement structure does not have. According to the actual need, it can be laid in any position of the thin plate with arbitrary curvature, so that the structure can get better sound vibration properties. Therefore, it is meaningful to study the influence of curved strengthening reinforcement on the Vibro-acoustic properties of structure.In this paper, the curved stiffened plate as the research object. Study the laying position, shape, period, amplitude and laying damping layer to the influence of the curved stiffened plate on the Vibro-acoustic properties.The main research work of this paper includes the following parts:(1)Based on the finite element theory, the finite element model of the thin plate and curved beam is established. Then by means of coordinate conversion make all curved beam element stiffness matrix and the nodal load vector from the local coordinate system transformation to the global coordinate system, and the finite element model of curved stiffened plate is established by the coordinate system of the thin plate. Finally, the natural frequency of the thin plate structure and the radiated sound power level are calculated by the aid of the acoustic software Virtual.lab, and the calculation results are compared with the results of the known paper, which verifies the correctness of the analysis method.(2)Research on the normal circular curved reinforced bar and the sine period reinforced bar in different forms and conditions, such as external load excitation position, thickness of the thin plate, height and width of the stiffener, the position of the stiffener laying on the plate, the shapes?period and amplitude of the stiffener and so on, the influence of the parameters on vibro-acoustic properties of the structure. Through the study of these parameters influence on the natural frequencies, the radiation sound power level of the structure, preliminary draw some conclusions, make some guidance for further study and experiments.(3)Study on the influence of the thickness of the free damping layer and the properties of the damping material on the acoustic radiation of the curved stiffened plate. Through the calculation analysis of thickness of the damping layer and the Young's modulus, density and the loss factor of the damping material on the radiation sound power level and field sound pressure level of influence. It is found that with the increasing of thickness of the damping layer, the suppression effect of damping layer on the radiated sound power of the structure is increased, with the increasing of the excitation frequency, restraining the radiated power level of the damping layer on the structure becomes larger, and the thickness of the damping layer is thicker and more obvious inhibition. The density of the damping material is not obvious to depress the structural vibration and noise, but the loss factor of the damping material is bigger, and the peak value of the radiated sound power level is smaller. This provides a basis for the selection of the parameters of the damping layer on the surface of the structure.