结构-声场耦合系统声压响应优化设计研究

Acoustic design optimization for coupled acoustic-structural systems

为了减小结构振动产生的噪声,基于结构-声场耦合有限元模型,对其在简谐力激励下的声响应进行了计算。在此基础上,以结构厚度为设计变量,保持结构重量相对不变并以设计变量的上、下限为约束,以设计域点在各频率响应声压平方和的平方根为目标函数,对其进行了优化设计研究。用软件N astran计算声响应及声敏度,基于iS IGHT对N astran的集成用可行方向法实施了优化。以一矩形板结构-立方体声场耦合系统为实例,得到了优化的结构厚度分布。优化后,设计域点的峰值声压级均有不同程度的降低,声压级降低最大值达32.8dB。结果表明声压响应优化设计,在保持结构重量相对不变的情况下,通过对结构重量的重新分布能达到较明显的降噪效果。

For the purpose of reducing structure-born noise, the finite element model of acoustic-structural coupled systems is biult and the acoustic response and sensitivity are calculated using Nastran FEM software under harmonic excitation. Then, the optimal geometric design of the structure is performed for the reduction of the acoustic pressure at interested positions and frequencies using the feasible direction method in iSIGHT optimization program. This method is applied to a plate coupled with a 3-dimension acoustic field as an example. The optimal thickness distribution is obtained with a 32.8 dE reduction of sound pressure level while the structural weight is relatively not changed. Results show that the optimal geometric design of the structural weight redistribution has an remarkabule efficiency on reducing noise.