The road noise problem in the frequency range of 35-40 Hz generated by a certain vehicle model on rough asphalt pavement at a speed of 30 km/h is analyzed by simulation and testing methods. Based on structural noise transfer path analysis (TPA) and node contribution analysis, it is determined that the problem frequency noise is mainly caused by low-frequency vibration of the vehicle body sheet metal parts. Therefore, based on the partial resonance principle, a resonance structure that can be industrialized according to the shape and local space of the sheet metal is designed, which is composed of a metal bracket and a metal block. By attaching this resonance structure to the sheet metal area with a significant contribution, simulation results show that the structure reduces the vibration of the sheet metal, thereby optimizing the interior noise. The peak noise levels in the front and rear seats are reduced by 8.6 and 6.4 dB, respectively. Meanwhile, the vehicle test results indicate that the interior noise has been improved by 7.0 and 5.8 dB. This provides a new research method and optimization scheme for controlling low-frequency noise caused by vibration of sheet metal.
| 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 |