硕士论文－车辆噪声控制与材料参数测试方法研究..doc

车辆噪声控制与材料参数测试方法研究当空腔深度为30mm，系统在中心频率200Hz附近产生共振，隔声频率特性曲线在该位置形成一个低谷；当空腔深度为40mm，隔声频率特性曲线在中心频率为160Hz位置形成一个低谷装饰板1号吸声材料40mm空腔50mm列车材料。条件允许下，应加大空腔的深度，使共振频率移到实用频率范围以下。analyze the sound insulation character, it show that when the cavity depth is 30mm, the sympathetic vibration exist around the centre frequency of 200Hz of the system, the frequency character contours of sound insulation represent a lowest value. While the cavity depth is 40mm, the lowest value is around 160Hz.according to these characters, the optimal group system can be determined, the order of the optimal group system from inside to outside of the car is as follows: decorate board, No.1 sound absorption, the cavity of 40mm, train material of 50mm.the resonance frequency can be acquired at a lower utility frequency bands by increasing the cavity depth at a permit grade. When using FFT and CPB to analyze the noise elimination of exhaust system, the effect is not so well when it is at a 2500rpm of rotate speed; here the fundamental frequency is 83.4Hz. the noise of the exhaust air system is made of two parts: second-order and forth-order noise play main part at a low rotate speed, while at the high rotate speed the main action of the noise is air current friction, and the friction become the main position instead of aerodynamic noise bit by bit with the increasing of the rotate speed. [Keyword] material combination insulation character exhaust system noise elimination 目录 车辆噪声控制与材料参数测试方法研究 1 1 引言 4 2 车辆噪声源的分析和评价 6 2.1 车辆噪声源识别研究概况 6 2.1.1 车辆噪声源的识别理论和方法 6 2.1.2 车辆噪声源识别实验研究 6 2.2 车辆噪声源的分析 6 2.2.1 磁悬浮列车噪声 6 2.2.2 汽车噪声与振动评价 7 2.2.3 通过噪声 8 2.2.4 喇叭噪声 10 2.2.5 排气系统的噪声源 10 2.2.6 车内噪声限值标准 10 2.2.7 汽车加速车外噪声限值 11 3 排气系统噪声的测试方法研究 12 3.1 消音元件声学评价指标 12 3.1.1 传递损失 12 3.1.2 插入损失 13 3.1.3 末端声压级差（减噪量） 13 3.1.4 衰减量 13 3.1.5 排气系统几种评价指标的比较 13 3.2 排气系统性能的测试方法 14 3.2.1 消声器发动机台架试验 14 3.2.2 排气系统几种评价指标的测量 15 3.2.3 本文中的排气噪声的测试方法 17 4 高速列车材料声学特性试验 19 4.1 试验综述 19 4.1.1 试验目的 19 4.1.2 试验材料和主要试验设备 19 4.1.3 试验的声学环境