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针对高声压级下有限厚度多孔金属板在线性阻抗背衬条件下(背衬表面声压与声质点速度为线性关系)的吸声问题,提出了一个描述不同声压级下材料层法向吸声性能的一维模型,并给出求解材料层内部声质点速度的线化与差分方法,以预测多孔金属板在高声压级下的非线性吸声特性。在阻抗管中对两块多孔金属板进行了声学测试,得到了材料层法向表面阻抗和吸声系数随入射声压级变化的实验结果。研究表明:实验与理论预测符合良好,验证了模型与数值方法的正确性。本文所提原理和方法,可用于一般硬质多孔材料。
Aiming at the problem of sound absorption of porous metal plate with finite thickness at high sound pressure level under the condition of linear impedance backing (the linear relationship between the surface acoustic pressure and acoustic velocity) Dimensional model of sound-absorbing performance, and the linearization and the difference method for solving the acoustic velocity in the material layer are given to predict the nonlinear sound absorption characteristics of porous metal plate under high sound pressure level. Acoustic tests were performed on two porous metal plates in an impedance tube. Experimental results show that the normalized surface impedance and the sound absorption coefficient of the material layer vary with incident sound pressure level. The research shows that the experimental and theoretical predictions are in good agreement with each other and the correctness of the model and the numerical method are verified. The principles and methods proposed in this paper can be used for general hard porous materials.