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In order to study the influence of sound absorption factors on automobile headliner, impedance tube is used to test the sound absorption characteristics of automotive headliner materials based on the transfer function method; the flow resistance of the headliner is tested based on the direct current method, to analyze the effects of production process, fabric, PU, glue and flow resistance on the sound absorption of the headliner. The results show that the production process, fabric layer and PU are the main factors affecting the sound absorption factors on the headliner. The sound absorption coefficient of the two-step production process is increased by 0.1~0.45 in the frequency range above 1 000 Hz; the sound absorption coefficient of knitted fabric is higher than non-woven fabric by 0.05~0.29 in the whole frequency range. Above the 1 000 Hz frequency, when the thickness or density of PU is increased, the sound absorption coefficient is increased by 0.02~0.43, and the peak of sound absorption is close to 1. The average sound absorption coefficient increases with the flow resistance. Reasonable selection of headliner with high flow resistance can effectively increase the resistance of sound wave propagating in the material, which is conducive to rapid attenuation of sound energy and improvement of sound absorption effect.
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| 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 |
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