【作者】 宋海生；

【导师】 史文库；

【作者基本信息】 吉林大学 ， 车辆工程， 2012， 博士

【摘要】 NVH为汽车振动（Vibration）、噪声（Noise）和声振粗糙度（Harshness）的英文缩写，是衡量汽车舒适性的一个综合性问题，NVH性能与顾客对于汽车的总体印象和评价直接相关。随着人们生活水平的提高，人们对于汽车的要求已不仅仅满足于代步，对于汽车的NVH性能提出了很高的要求。传递路径分析方法（TPA-Transfer PathAnalysis）是一种解决汽车NVH问题的研究方法，经过20多年的发展，在国外该方法已被广泛应用于汽车的噪声与振动源的定位，并获得了NVH领域的广泛认可，而在国内对于该方法的研究则相对较少。传递路径分析方法在实际应用中已经衍生出很多种方法，其中传统TPA方法是目前公认的精度较高的方法，其他传递路径方法都是在这一方法的基础上发展起来的。但是，传统TPA方法建模时间较长、建模需要的试验工作量较大的缺点严重制约了它的广泛应用。为了提升建模效率，OPA（Operational TPA）方法被提出，该方法的优点在于建模时间较短，但是容易出现丢失路径或错判路径贡献量的现象。为了克服上述方法的缺陷，OPAX（Operational-X TPA）方法被提出，该方法是在传统TPA方法基础上演化而来，同时借鉴了OPA方法的优点，建立的模型精度可以与传统TPA方法相媲美，同时建模效率与OPA方法相当，是一种兼具精度与效率的传递路径分析方法。目前，国内外对于OPAX方法的研究还比较少，而关于OPAX方法在实际工程应用中的研究更是少之又少。本文依托吉林大学与国内某汽车企业合作的《某轻型客车NVH性能提升》项目展开对OPAX传递路径分析方法的研究。论文从理论和试验建模两个方面论证了OPAX方法相对于传统TPA方法和OPA方法的优越性，并引入条件数理论和决定系数理论，对OPAX方法的质量判据体系进行完善的同时进一步提升了建模效率。在此基础上，通过大量试验提炼出可以指导工程实际的OPAX建模经验公式，并将其应用于某国产轻型客车的振动控制中进行传递路径贡献量分析，依据分析结果提出改进措施，有效地解决了该车振动比较剧烈的问题，同时也证明了论文提出的经验公式作为一种普遍适用于工程实际的OPAX建模指导原则是合理有效的，在保证结果精度的前提下最大限度地减小了OPAX建模的工作量，为OPAX方法在汽车NVH方面的推广应用奠定了理论基础。论文的主要工作包括以下几个部分：1.论文首先对传递路径分析方法的研究现状进行了总结，并在此基础上简要介绍了传递路径分析的基本理论、频率响应函数理论和相干函数理论；其次对于传统TPA方法、OPA方法和OPAX方法的理论基础进行了详细的阐述，重点介绍了各方法的优缺点。传统TPA方法精度较高但是建模周期较长，OPA方法虽然具有较高的建模效率但是结果精度较差，OPAX方法是一种兼具精度与效率的方法；然后针对OPAX方法进行了详细论述，重点介绍了OPAX方法的建模流程、参数化工作载荷识别模型及OPAX方法的可伸缩性等方面；最后引入条件数理论和决定系数理论作为OPAX方法的间接和直接质量判据，并从理论上给予说明。2.为了进一步说明OPAX方法的优越性，论文以某国产轻型客车为例，针对发动机悬置、排气悬吊及车内测点分别采用传统TPA方法、OPA方法和OPAX方法建立了传递路径分析模型。对比了三种方法的频响函数FRF识别精度、工作载荷识别精度、路径贡献量计算的准确度及建模所消耗的时间，结果表明OPAX方法兼具了传统TPA方法的精度和OPA方法的效率，可以较好地应用于工程实际。3.在以上工作的基础上，论文对OPAX方法进行了扩展研究。OPAX方法在实际应用中既可以采用较少的参数进行问题的快速判断，也可以采用较复杂的模型以提高评估结果的精度，这就是OPAX方法的可伸缩性。如何在保证结果精度的前提下采用尽量少的参数进行OPAX建模一直是困扰工程人员的问题，为了解决这一问题，论文对关系到OPAX结果准确度的四个参量进行了大量的试验研究，以本文提出的条件数和决定系数作为间接和直接质量判据，总结出可以指导工程实际的OPAX建模经验公式，在保证结果精度的前提下最大限度地减少了OPAX建模的工作量。4.为了验证本文提出的经验公式的正确性和适用性，论文针对某国产轻型客车在90km/h-110km/h车速下整车振动较为剧烈的问题，根据本文总结的经验公式建立了整车的OPAX模型，并进行了传递路径贡献量分析，找到了导致这一问题的主要贡献量路径为后悬架--车身系统传递路径。为了了解该传递路径的系统特性，论文进行了白车身模态仿真计算和白车身模态试验，确定了车身的前三阶模态是导致该传递路径系统频响函数峰值的原因。为了了解该传递路径的载荷激励特性，论文进行了后悬架系统的偏频试验，分析得知轮胎的滚动激励频率与后悬架非簧载偏频的耦合是导致该传递路径载荷激励存在峰值的主要原因。最终确定引起整车剧烈振动的原因在于轮胎滚动激励频率、后悬架非簧载偏频和车身前三阶固有频率之间的耦合，为该问题的解决提供了清晰的改进思路。论文研究结果表明本文提出的经验公式是正确的，可以较好地应用于工程实际。5.基于以上扩展OPAX方法的分析结果，制定了改进方案。结合有限元分析结果和厂家生产实际制定了车身改进措施，先在有限元模型中进行了初步验证，然后试制了样件安装在车身上进行了模态试验的验证，确认了改进措施的效果。更换了新花纹轮胎，进行了轮胎的径跳试验和动平衡试验，使其满足技术要求，从而降低激励能量的输入。最后试制了样车，采用了全部的改进措施，并将改进样车的试验结果与原车进行了对比，结果充分说明了本文提出的改进措施的有效性。论文对OPAX传递路径分析方法进行了深入的扩展研究，并首次将其与轻型客车的NVH实际问题相结合，系统的阐述了扩展OPAX方法在轻型客车振动控制中的应用，形成了一整套基于扩展OPAX方法解决整车NVH问题一般可推广的理论、方法和流程。论文研究成果对于汽车NVH问题的研究具有较高的工程实用价值，对于类似的工程问题也具有一定的参考意义。更多还原

【Abstract】 NVH (Vibration、Noise and Harshness) is the comprehensive problem to measurevehicle comfort, which is closely related to customer impression and assessment for vehicle.With the living standard improving, NVH performance standard is rising. TPA-Transfer PathAnalysis, as a research method for NVH, has been widely applied to noise source andvibration source positioning for 20 years, being widely accepted abroad, but uncommon inchina.TPA has derived a lot of methods in practical application. Among them conventionalTPA is generally acknowledged as the most precise one and others are developing based on it.However, the disadvantage of long modeling period and hard test workload restrict its wideapplication. OPA is proposed to improve modeling efficiency. The measure has theadvantage of short modeling period but it’s easy to lose path or make erroneous judgment ofpath contribution amount. To overcome the defects, OPAX is proposed. The method isderived on the base of the TPA and it includes the advantage of OPA. It’s a method with themodeling precise of TPA and modeling efficiency of OPA. At present, the research on OPAXis pretty limited and its engineering application is rather rare at home and abroad.Further research on Operational-X TPA is the goal of this work that was relied on thecooperative project“A light bus NVH performance improving”of Jilin University and anenterprise. In the paper, the advantages of Operational-X TPA over conventional TPA andOperational TPA have been proved from the theory and test, and the theory of conditionnumber and coefficient of determination was introduced to Operational-X TPA to improvequality criteria. On this basis, the OPAX empirical formula was put forward through a lot oftests and applied to a light bus to study on contribution of transfer path. Improvementmeasures were implemented and the results prove that vibration was attenuated and theempirical formula is effectively for NVH problem. The main contents of the paper are as followed:1. The research status of the TPA is summarized in the paper and the basic theory ofTPA, the frequency response function theory and the coherence function theory areintroduced. The theoretical basis of the TPA, OPA and OPAX is detailedly exposited and theadvantage and disadvantage of the methods are introduced. For instance, TPA has highprecise but long modeling period and OPA has high modeling efficiency but poor precisionwhile OPAX is a method with precision and efficiency. The modeling process，parametricworking load model and scalability of the POAX are introduced. The theory of conditionnumber and coefficient of determination, being used as the indirect and direct quality criteriais introduced and the theory proof is given.2. For further illustrating the advantages of OPAX, the conventional TPA model、Operational TPA model and OPAX model of engine mount and exhaust suspension werebuilt and the identification precision of FRF、operational loads and contribution of transferpath and the time consuming of three models were contrasted. The results show that OPAXhas great precision and efficiency and can be applied to NVH problem preferably.3. Based on the above work foundation, the paper makes patulous research on OPAX.The OPAX could not only make quick judgment with less parameters but also could improvethe structure precision by using the complex model in the practical application which isknown as scalability. However, the problem of how to build OPAX model using lessparameters by the premise of guarantee of getting high result precision always puzzles theresearchers. To solve the problem, a lot of tests of four parameters related to the OPAX resultprecision have been conducted. The condition number and coefficient of determination asindirect and direct quality criteria is introduced in the paper and OPAX modelingexperiential formula which could guild the engineering is summarized. The workload ofOPAX modeling is decreased by the premise of guarantee of getting high result precision.4. For illustrating the correctness and applicability of the OPAX empirical formula, theOPAX model was built and the analysis on contribution of transfer path was carriedaccording to a light bus vibration problem in speed of 90km/h-110km/h. The results confirmed that the transfer path of rear suspension--car body has the most contribution. Tounderstand characteristics of the transfer path, the modal simulation and experiment wereconducted and first three orders modal was confirmed as the reason of bad characteristics ofthe transfer path. To understand characteristics of the operational loads, the rear suspensionexperiment was conducted and the coupling between tire rolling excitation and the rearsuspension offset frequency was confirmed as the reason of bad characteristics of theoperational loads. Finally, the coupling of tire rolling excitation、the rear suspension offsetfrequency and the first three orders modal of body was confirmed as the reason of the lightbus vibration problem. The research results of this paper show that the OPAX empiricalformula is correct and can be applied to NVH problem preferably.5. The improved scheme is made based on the analysis results of the OPAX. First,changing a new tire tread pattern and making the radial runout test and dynamic balance testmake it satisfy the technical requirements and reduce the input of the excitation energy. Then,combine the FEM analysis results with improved measures made by manufactures, and theimproved method is verified in FEM model and verified by modal test in the vehicle whichwas installed with a sample piece. At last, the sample vehicle is made by using all theimproved measures. The test of the original and improved vehicle is made respectively andthe improved measures are improved effective.In this paper, the OPAX has been researched deeply and applied to a light bus vibrationproblem for the first time. A complete theory and procedure of OPAX application in NVHproblem was proposed. The results of this paper have great practical value and referencesignificance to similar problems.更多还原