Fig. 1. Form function of the solid spheres for two materials.两种材料实心球形态函数幅频特性曲线

Fig. 2. Dispersion curves of the solid PMMA sphere: (a) Real-imaginary of eigenvalue; (b) normalized phase velocity.实心PMMA球频散曲线　(a)特征值实部-虚部; (b)归一化相速度

Fig. 3. Ray diagram for subsonic Rayleigh waves propagating around the sphere.亚音速Rayleigh波传播路径

Fig. 4. (a) Normalized dispersion curve of subsonic Rayleigh waves (black dotted line) and curves of 2ka/(2p + 1) (blue line); (b) pure elastic resonance. (a)亚音速Rayleigh波归一化相速度(黑色点划线)和曲线2ka/(2p + 1)(蓝色线); (b)纯弹性共振

Fig. 5. Sensitivity of resonance-frequency: (a) f_ref = 4.15 kHz; (b) f_ref = 16.05 kHz. PMMA球两个典型共振峰频率敏感度　(a) f_ref = 4.15 kHz; (b) f_ref = 16.05 kHz

Fig. 6. Sensitivity of resonance-amplitude: (a) f_ref = 4.15 kHz; (b) f_ref = 16.05 kHz PMMA球两个典型共振峰幅度敏感度　(a) f_ref = 4.15 kHz; (b) f_ref = 16.05 kHz

Fig. 7. Sensitivity of resonance frequency to attenuation: (a) f_ref = 4.15 kHz; (b) f_ref = 16.05 kHz. 共振频率对衰减系数敏感度　(a) f_ref = 4.15 kHz; (b) f_ref = 16.05 kHz

Fig. 8. Flow chart of material parameters inversion.材料声学参数反演技术流程图

Fig. 9. Cost function of resonance frequency: (a) ; (b) 频率代价函数　(a) ; (b)

Fig. 10. Relative errors of the transverse wave velocity and the longitudinal wave velocity.剪切波和纵波声速相对误差

Fig. 11. Cost function of resonance amplitude: (a) ; (b) . 幅度代价函数　(a) ; (b)

Fig. 12. Relative errors of the longitudinal wave attenuation coefficient and the transverse wave attenuation coefficient.纵波和剪切波衰减系数相对误差

Fig. 13. Arrangement of experimental system.实验布放及测量仪器

Fig. 14. Time-domain signal: (a) Echoes; (b) incident pressure.时域信号　(a)回波; (b)入射波

Fig. 15. Flow chart of obtaining form function.获取形态函数流程图

Fig. 16. Cost function: (a) Resonance frequency; (b) resonance amplitude.代价函数　(a)共振峰频率; (b)共振峰幅度

Fig. 17. Comparison between experimental and theoretical calculation.实验结果和理论计算对比