反射体对U型梁贴附式吸声材料插入损失影响的实验研究

Tests for influences of reflector on insertion loss of a U-beam's adhesive sound-absorbing material

为了探究反射体对U型梁贴附式吸声材料插入损失的影响,根据车厢轮廓建立模拟反射体进行实验研究。利用声线理论分析了当反射体存在时,由于中高频噪声经过反射体与吸声材料表面间的多次反射逐渐消耗能量,使插入损失比没有反射体时增大;实验结果表明,对于U型梁外侧的噪声敏感区,反射体存在时的插入损失值明显大于没有反射体时;各测点的1/3倍频程插入损失曲线表明,反射体的存在对中高频段噪声的影响较大,对低频段噪声影响较小。本实验为评价某新研发的贴附式吸声材料在U型梁腹板内侧使用时的实际降噪效果提供参考。

In order to investigate effects of reflector on insertion loss of a U-beam ’s adhesive sound-absorbing material,an analog reflector was constructed for tests based on the outline of a train car. The test results were analyzed using the sound line theory. It was shown that when a reflector exists,noise within medium and high frequency ranges after repeated reflections between reflector and a U-beam’s adhesive sound-absorbing material gradually dissipates energy,the insertion loss increases; in the noise sensitive area outside the U-beam,the insertion loss during reflector existing is significantly larger than that be during absence of reflector; the 1/3 octave insertion loss curve for each measured point reveals the existence of reflector has a larger influence on noise within medium and high frequency ranges but a less influence on noise within a lower frequency range. This study provided a reference for evaluating the actual noise reduction effect of a certain newly developed adhesive sound-absorbing material used at the inner side of a U-beam’s web.