基子OTPA方法的挖掘机驾驶室结构噪声研究

发布时间：2018-05-09 07:09

本文选题：工况传递路径分析 + 奇异值分解　；参考：《山东大学》2017年硕士论文

【摘要】：挖掘机的NVH性能直接影响着驾驶员的身心健康,是挖掘机产品的核心竞争力所在,越来越多地受到工程技术人员的关注。驾驶室噪声是挖掘机NVH性能的重要指标之一,尽可能多地降低工程噪声是改善NVH性能的关键。因此,对挖掘机驾驶室内噪声进行研究,对于探究噪声产生原理以及提出有效改进措施,具有一定的理论研究意义与工程应用价值。本文基于工况传递路径分析方法(OTPA),结合"XX型挖掘机噪声控制"项目这一工程实践背景,对某型液压挖掘机驾驶室内噪声的结构声成分进行研究,并提出改进措施。首先,研究以OTPA原理为理论基础,推导出系统传递函数和路径贡献的计算方法。并且针对该方法存在的不足对其进行改进:(1)通过对比合成信号和实测信号的频谱图,确定是否遗漏重要路径;(2)通过应用奇异值分解技术处理测试数据,提高OTPA模型计算准确度。其次,通过分析驾驶室内噪声来源及其传播方式,以发动机振动激励为系统输入,以驾驶室内司机右耳耳旁噪声为输出,建立从上车架上发动机4点安装位置到驾驶室耳旁的OTPA模型。进而设计试验,选择1140r/min、1254r/min、1430r/min、1650r/min、1765r/min、1870r/min 转速下的实测数据构建 OTPA 模型,得到系统传递率函数和路径贡献;选择950r/min、1545r/min、2100r/min转速下的实测数据进行OTPA模型验证,对比实测输出信号和合成输出信号的频谱图,发现OTPA模型准确有效,可用于后续降噪方案分析。最后,应用改进后的OTPA方法,对测试数据进行处理,通过在分析工况下对OTPA模型的传递率函数和路径噪声贡献进行分析,确定待改进的重点传递路径与敏感频率位置。分析结果显示,挖掘机发动机左后位置减振器和系统结构共振点所对应的敏感频率位置是重点优化改进方向。针对结构共振问题,基于模态分析法,对挖掘机上车架结构进行整改优化,并对改进效果进行了验证。研究表明,将OTPA方法用于液压挖掘机发动机振动到驾驶室结构噪声之间的路径传递研究是可行的,OTPA方法不但可以有效识别噪声源,还可以定位对系统输出影响较大的路径,为解决驾驶室噪声问题提供了可靠的理论指导。
[Abstract]:The NVH performance of excavator directly affects the physical and mental health of the driver. It is the core competitiveness of excavator products and is paid more and more attention by engineers and technicians. Cab noise is one of the important indexes of excavator NVH performance. Reducing engineering noise as much as possible is the key to improve NVH performance. Therefore, the research on the noise in the cab of excavator has certain theoretical significance and engineering application value for probing into the principle of noise generation and putting forward effective improvement measures. Based on the method of operating mode transfer path analysis and the project background of "XX excavator noise control", this paper studies the structural sound composition of the noise in the cab of a hydraulic excavator, and puts forward some improvement measures. Firstly, based on OTPA principle, the calculation method of system transfer function and path contribution is derived. Aiming at the shortcomings of this method, we improve it. (1) by comparing the spectrum of the synthetic signal and the measured signal, we can determine if the important path is missing. (2) by using singular value decomposition technology to process the test data, we can improve the accuracy of the OTPA model calculation. Secondly, by analyzing the source of the noise in the cab and its transmission mode, the engine vibration excitation is taken as the system input, and the noise near the right ear of the driver in the cab is taken as the output. The OTPA model from the 4 o'clock position of the engine on the upper frame to the ear of the cab is established. And then design the experiment, select the measured data of 1140 r / min 1254 rmin 1430 r / min 1650 r / min 1765 r / min 1870 r / min to build the OTPA model, and get the system transfer rate function and path contribution, and select the measured data at 950 r / min 1545r / min / min 2100r / min to verify the OTPA model. It is found that the OTPA model is accurate and effective and can be used in the analysis of the subsequent noise reduction scheme by comparing the spectrum of the measured output signal with the synthetic output signal. Finally, the improved OTPA method is used to process the test data. By analyzing the transfer rate function and the path noise contribution of the OTPA model, the key transfer path and the sensitive frequency position are determined. The analysis results show that the sensitive frequency position corresponding to the shock absorber of the left rear position of the excavator engine and the common vibration point of the system structure is the key optimization direction. Aiming at the problem of structural resonance, the structure of excavator frame was optimized based on modal analysis method, and the improvement effect was verified. The results show that it is feasible to use OTPA method to study the path transfer between engine vibration and cab structure noise of hydraulic excavator. It can not only effectively identify the noise source, but also locate the path which has a great influence on the system output. It provides reliable theoretical guidance for solving cab noise problem.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU621

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