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本研究的主要目的是确定用于北美铁路的典型货运机车司机室的振动特性和评价各种结构修改对司机室内部噪声和振动的效果。为此 ,在试验室环境中研究了一台批量生产型机车司机室的结构动力学特性。以接近类似司机室在现场承受的输入方式用液压致动器对其激振。通过一系列试验 ,建立司机室的振动基线 ,并确定司机室各部分如何振动。然后 ,对司机室地板和顶盖进行一系列修改以降低振动水平。试验结果表明 ,加强司机室地板刚度可以降低频率在 2 0 0Hz以下的司机室内部噪声和振动。然而 ,这种降低是以增加高频振动为代价的。在司机室顶盖结构中加减振材料可看到相似的连带关系。加入减振材料降低了某些加速度峰值 ,而在 5 3Hz下却增加了一个峰值。本研究的结果指出 ,实际上 ,在能够作出哪种解决方法对于某种特定的应用场合是最有效的决定之前 ,必需对不同的噪声和振动解决办法分别进行试验。然而 ,只有在结构噪声和振动特性和主要噪声源已经被识别的情况下才可能作出这种决定。本文描述的实验室装备对于创造一个有助于可精确和重复评价不同噪声和振动解决方法的环境特别有效 ,而司机室结构则以与它在现场相同的方式被激振。没有这样的试验装备 ,许多解决方法的效果就不可能被精确地确定。
The main purpose of this study was to determine the vibration characteristics of a typical freight locomotive cab used on North American railroads and to evaluate the effects of various structural modifications on cab interior noise and vibration. To this end, the structural dynamics of a batch production locomotive cab has been studied in a laboratory environment. It is excited by a hydraulic actuator in a manner similar to the way in which similar cabs are subjected to on-site input. Through a series of tests, a baseline of cab vibration was established and how various parts of the cab were vibrated. Then, a series of modifications were made to the cab floor and roof to reduce vibration levels. The test results show that strengthening the stiffness of the cab floor can reduce the noise and vibration of the cab interior at frequencies below 200 Hz. However, this reduction is at the cost of increased dithering. In the driver’s cab roof structure plus damping material can see a similar relationship. Adding damping material reduces some of the acceleration peaks, but adds a peak at 53Hz. The results of this study point out that in practice it is necessary to experiment with different noise and vibration solutions before it is possible to decide which solution is the most effective for a particular application. However, such a decision may be made only if the structural noise and vibration characteristics and the main noise source have been identified. The laboratory equipment described in this article is particularly effective at creating an environment that helps to accurately and repeatedly evaluate different noise and vibration solutions while the cab architecture is excited in the same manner as it is in the field. Without such test equipment, the effectiveness of many solutions can not be precisely defined.