Finite Element Analysis And Experimental Validation For Structure-acoustic Coupling Of Membrane

Flexible membrane structure has been widely used in fields of aviation, aerospace, construction for its good characters such as light weight, easy to fold, however, compared with rigid structure, since it has more flexibility, the flexible membrane structure is easy to be influenced by environmental interference, especially under large acoustic loads. In order to study the structure-acoustic coupling performance of membrane, finite element method and experiment are conducted to investigate the vibration characteristics of membrane backed a cavity and the pressure distribution of membrane-cavity interface.FE models of pure membrane and membrane-cavity system are established in this paper, modal analysis for both two models are carried out to obtained their natural frequencies and vibration modes, comparative study of the different results sheds light on whether structure-acoustic coupling has an effect on vibration performance of membrane, besides, effects of membrane’s thickness, prestressed size and surface density on its dynamic behavior are also be discussed before a harmonic response analysis for the membrane backed a cavity. The acoustic element is used in FEM to simulate the interface between membrane and inner acoustic fie ld and thus obtain the pressure distributed there. Through studying the sound pressure distribution inside the cavity, the transmission of acoustic wave is well understood, meanwhile, the relationships of membrane deformation, interface pressure and the frequency as well as amplitude of exciting force under the cavity are also be found by FEM.As for the experiment part, a setup for studying structure-acoustic coupling effect of membrane is founded. In this experiment, the membrane is fixed on an aluminum-made cavity, and the acoustic radiation source is simulated by an actuator with a piston. The vibration information of membrane and support plate as well as the acoustic pressure inside cavity can be captured by the laser displacement sensor, pressure sensor and acceleration sensor respectively. Fast fourier transform and some related modal algorithm are used to obtain the natural frequency and mode shape of membrane-cavity, the results of which are compared with FEM result for comparative study. Moreover, the relationship between membrane-cavity interface pressure and exciting frequency of actuator is also investigated by experiment. In the end, the differences of inside interface pressures between cylinder cavity structure and cuboid cavity structure, both of which changes with the excitation frequency size, are compared.