An acoustic black hole stiffened plate was designed based on acoustic black hole and stiffener structures. Acoustic radiation characteristics, vibration energy distribution and transmission characteristics were studied by establishing the finite element model of the acoustic black hole stiffened plate. The simulation results show that the radiated sound power of the acoustic black hole stiffened plate is 8~20 dB lower than that of ordinary stiffened plates above the cut-off frequency. Because of the local damping layer, the vibration gathered in the acoustic black hole’s region is effectively dissipated. Therefore, the vibration level is significantly lowered and the acoustic black hole stiffened plate is weakly coupled to the sound field. It is verified that most of the kinetic energy of the acoustic black hole stiffened plate is concentrated in the acoustic black hole region while analysis of the vibration energy distribution characteristics shows that the vibration level of the overall structure is reduced. It is revealed that the acoustic black hole stiffened plate is affected by the superposition effects which include acoustic black hole’s concentrating energy effect and stiffened plate’s blocking vibration effect. Compared with ordinary stiffened plates, acoustic black hole stiffened plates have better vibration and noise’s reduction performance.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |