A simplified finite element method (FEM) simulation method has been established and validated for analyzing the sound absorption mechanism of structures with periodic axisymmetric cavities. Combined with genetic algorithm, the simplified FEM method is used to optimize the sound absorption coefficient of the structure containing periodic cylindrical cavities and variable cross section cavities. The result of variable section cavities is much better than the case of cylindrical cavities. The effect of cavity shape on sound absorption mechanism is discussed through energy dissipation, structure deformation and modal analysis of the absorption structures. It is found that the cavity structure resonances include bending vibration of the surface layer and radial motion of particles near the cavities. The radial motion also changes along the axial direction. Adding geometric design parameters of the cavity cross section are conducive to moving the radial mode to low frequency. The radial vibration has a great influence on absorption performance, which is more conducive to promoting the conversion of longitudinal waves into transverse waves with more energy dissipation. Finally, a better sound absorption performance is obtained by introducing the material parameter of Young's modulus into the optimization model, indicating that comprehensive consideration of geometry and material parameters for optimization is expected to obtain the desired sound absorption structure in engineering practice.

建立了一种简化的有限元模拟方法，用于分析周期性轴对称空腔结构的吸声机理。结合遗传算法，采用简化的有限元方法来优化包含周期性圆柱腔和变截面腔的结构的吸声系数。可变截面腔的结果比圆柱形腔的情况要好得多。通过能量耗散，结构变形和吸声结构的模态分析，讨论了腔体形状对吸声机理的影响。发现腔结构共振包括表面层的弯曲振动和腔附近的颗粒的径向运动。径向运动也沿轴向方向变化。添加空腔横截面的几何设计参数有利于将径向模式移至低频。径向振动对吸收性能有很大影响，更有利于促进纵波向横波的转换，并具有更大的能量耗散。最后，通过将杨氏模量的材料参数引入到优化模型中，可以获得更好的吸声性能，这表明在工程实践中，综合考虑几何形状和材料参数以进行优化有望获得所需的吸声结构。径向振动对吸收性能有很大影响，更有利于促进纵波向横波的转换，并具有更大的能量耗散。最后，通过将杨氏模量的材料参数引入到优化模型中，可以获得更好的吸声性能，这表明在工程实践中，综合考虑几何形状和材料参数以进行优化有望获得所需的吸声结构。径向振动对吸收性能有很大的影响，更有利于促进纵波向横波的转换，并具有更大的能量耗散。最后，通过将杨氏模量的材料参数引入到优化模型中，可以获得更好的吸声性能，这表明在工程实践中，综合考虑几何形状和材料参数以进行优化有望获得所需的吸声结构。