密闭腔体声-结构耦合系统的动力灵敏度分析

以密闭空腔为对象，开展了声-结构耦合系统的动力分析和灵敏度计算，为系统性态优化设计提供理论和算法基础。分别把结构和声场进行离散化，推导了声-结构耦合系统的有限元方程，求解了耦合系统的频率和声压级响应。在此基础上，以结构尺寸为设计变量，计算了耦合系统的固有频率和声压级响应的灵敏度，解决了声-结构耦合系统动力灵敏度的数值算法问题。

Dynamic sensitivity analysis for acoustics-structure coupled systems with sealed cavities

An approach for dynamic analysis and sensitivity computation of sealed cavities is presented as a part of theoretical preparation for optimal acoustic performance designs.The structure and the sound field are discretized with 4-node thin plate element and 6-node isoparametric hexahedral elements,respectively.The governing finite element equation of the coupled system is derived with unsymmetrical system coefficient matrices.An eigenvalue problem is analyzed through the conjugate subspace iteration method to obtain the natural frequencies and normalized modal vectors of the coupled system.The method of modal superposition is used for solution of structural displacements and sound pressures.For the sensitivities of natural frequencies and sound pressures,the efficient semi-analytical method is used to determine the derivatives of frequencies and sound pressures with respect to size variables.The aforementioned approach has been implemented into JIFEX,a large-scale finite element analysis and structural optimization system.In the numerical examples,the accuracies of sensitivities of natural frequencies and sound pressure levels are compared with the ones through the global difference approach.In addition,errors of sound pressure sensitivities are presented with various numbers of terms used in the modal superposition method.