【作者】 李奇志；

【导师】 陈国平；

【作者基本信息】 南京航空航天大学 ， 工程力学， 2013， 博士

【摘要】 环境振动试验是考核、评定产品对于耐振动环境适应性的一种重要研究手段。振动试验实施过程中，振动试验条件的归纳及确定、夹具设计和传感器布置等条件直接影响产品耐振动能力考核的真实性、可靠性、有效性。本文针对环境振动试验中存在的若干问题，对环境振动试验方法及技术进行了以下几个方面的研究：(1)为了对设备振动环境的实测数据进行处理，从而确定环境振动试验条件，本文从理论出发，推导出振动环境实测数据归纳的基本原理，然后，依据参数的无偏估计理论，在不依靠人为给定置信度的条件下，推导出给定概率下无偏的随机数据实测归纳方法，并运用于国内某设备安装平台振动环境数据的处理，得到振动环境下实测归纳曲线。(2)在获取试件振动环境实测谱后，为了快速获得准确的加速因子，本文基于对Palmgren-Miner疲劳累积损伤原理和随机振动应力作用下累积损伤分布特点的分析，推导出随机振动应力作用下的加速因子计算方程，同时结合加速寿命试验理论进行了样件的加速寿命试验，通过对试验数据的Weillbull模型验证和最小二乘数据处理，获得了样件的振动加速因子。(3)在试验实施过程中，为了快速获得最优的加速度控制传感器布置位置，本文依据电动振动台多点控制原理和夹具传递函数特性，建立了传感器布置优化计算模型，然后，以某夹具为例建立有限元模型，利用Patran和Nastran软件求出频响函数，并根据所建优化模型求出传感器最优布置位置，最后通过夹具振动试验测试传力点响应谱。结果表明优化布置时所测传力点响应加速度谱密度偏离度明显小于传统凭经验布置时测得的响应加速度谱密度偏离度。(4)为了解决振动试验过程中夹具传递给试件的振动量级的输入严重不均匀和偏离参考谱加速度均方根值的问题，本文在分析电动振动台振动试验过程和夹具频响函数特性的基础上，建立了多点控制情况下基于响应加速度谱密度偏离度最小的夹具优化计算模型，然后以某夹具为例，利用Patran和Nastran软件计算夹具的传递函数，根据所建优化模型求取夹具优化设计参数，最后通过对优化前后的数据进行比较及振动试验测试，证明该优化方法是可行的和实用的。(5)在振动试验夹具设计和传感器布置仿真计算过程中，为了能获得较准确的结合部仿真模型，本文通过运用赫兹接触理论和Greenwood—Williamson模型推导出实际接触面积计算公式，建立了实际接触面积内有限元单元节点刚性连接的结合部建模理论，同时以某印制板夹具组件为例，建立夹具有限元仿真模型，并通过实测模态和仿真模态的非平动前四阶模态的比较和MAC计算，证明所建夹具组合模型能够满足工程计算需要。更多还原

【Abstract】 Ambient vibration test is an important research means in the assessment and evaluation ofproduct vibration environmental adaptability. In the process of test implementation, determination andinduction of vibration test conditions、fixture design and layout of sensors or other conditions directlyaffect the authenticity、reliability and validity of the product vibration resistance ability evaluation.This paper focus on the existing problems of environmental vibration test to study in the followingaspects, including:(1) In order to determine the vibration test conditions with processing of the measured data ofequipment vibration environment, the basic principle in induction of random environment measuredata was deduced from the theory. Then, based on equation of cumulative of frequency function underthe normal school, combining with the theory of unbiased evaluation, a new method was derived forinduction of random environment measure data under the given probability value. Consequently, themethod was used for dealing with data coming form an equipment, and an induction curve wasconcluded from the natural measure data of vibration environmnet.(2) Determining the acceleration factor which describes the equivalent relation between the timeand vibration level is one of the important steps during the vibration durability test. In order to obtainthe acceleration factor, based on the law of palmgren-miner fatigue cumulative damage and the theoryof cumulative damage under stationary narrow and wide band stress, the calculation equation ofacceleration factor is derived. The accelerated life equation, combining with the accelerated lifetesting theory, is used to design the prototype of the accelerated life test. The test is implemented, thenthe test data is verified by weillbull model and processed by least square method, finally the specimenmaterial vibration acceleration factor can be obtained.(3) In order to obtain the optimal acceleration sensor placing location, according to the electricvibration table multi-point control principle and the characteristic of transfer function, a sensorplacement optimization calculation model was established. A fixture was taken as an example toestablish it’s finite element model, nastran software was used to get the transfer function. Then anoptimal acceleration sensor placing location was obtained according to the optimization modelpreviously mentioned. Finally, the response of the connection place between the fixture and a testsample was measured with the fixture vibration test. The test results indicated that the mean squaredeviation of the response acceleration obtained with the optimization method is significantly smallerthan that with the traditional method. (4) In order to solve the phenomenon of the severely uneven vibration magnitude passed by thetest fixture to the Specimen and deviation from the reference spectral acceleration rms value,according to the electric vibration table multi-point control principle and the characteristics of afixture frequency response, a fixture design optimization model was established. Taking a specimenfixture design as an example, the fixture FRF value was calculated by Nastran software, then theoptimal design parameters of fixture was obtained according to the optimization model previouslymentioned. Optimization results indicated that the mean square deviation of response accelerationand the acceleration rms variation range obtained the optimization method are all significantly smallerthen that with the traditional method, while the vibration test results show that the variation range ofthe acceleration rms measured on the transfer point in the vibration test is basically the same with theresult coming form the optimization calculation.(5) In order to obtain the combined simulation model accurately in the design of fixture andlayout of sensors in the process of simulation, the calculating formula of real contact area in thecombination party was inferred with the Hertz contact theory and Greenwood-Williamson model.Then, the theory of finite element nodal rigid connecting mode was established. A clamp assembly ofa printed circuit board was taken as an example to establish the finite element simulation model, bycomparing the non translational first four modes measured modal with the modes of the simulationcalculation and calculating the MAC value, the fixture assembly model is demonstrated that it is rightand can meet the engineering need.更多还原