中文摘要：

声振耦合是航空航天飞行器在运行过程中备受关注的问题。针对具有代表性的薄壁圆柱结构,建立声场—结构直接耦合的三维动力学模型,其中结构和声场分别采用实体有限元和三维声单元剖分,并且采用无限元模拟自由声场边界。通过理论和数值分析研究声场中薄壁圆柱结构的模态、幅频响应、相频响应等振动特性的变化规律,讨论声振动对结构动力特性的影响及机理。研究发现声场在大多数情况下降低了结构的固有频率,在低频段声振动相当于给结构增加了附加质量,但是在高频段,声振动和结构阻尼的影响比较相似。随着声场流体密度增大,结构的大多数固有频率值明显减小,结构响应幅值在低频段增大,在高频段减小。声速对声场模态有显著影响,但是对结构模态频率的影响不大。

英文摘要：

The acoustic-structure coupling problem is much concerned in the running process of the aerospace vehicle.Aiming at a representative thin wall cylindrical structure,a 3-D dynamic model of acoustic-structure direct coupling is built.The modeling involves solid finite elements for the structure and 3-D acoustic elements for the sound field,and the infinite elements are employed in describing the free boundary conditions.The vibration characteristics of the light fluid-thin wall cylindrical structure,such as modal,amplitude and phase frequency response,are investigated through theoretical and numerical analyses.The effects of acoustic vibration on the structural dynamic characteristics and the corresponding mechanism are discussed.It is found that the natural frequencies of the structure are decreased in most cases due to the effects of sound field.In low frequency stage,the structure is added with some mass due to the acoustic vibration.But,the effects of acoustic vibration are similar to the effects of damping in high frequency stage.With the rise of fluid density,most natural frequencies decrease remarkably.The amplitudes of structural response increase in low frequency stage and decrease in high frequency stage.The sound velocity has remarkable influence on sound field mode,but has little influence on structural mode frequencies.