Approximate Analytical Determination of Vibrodiagnostic Parameters of Non-Linearity of Elastic Bodies Due to the Presence of a Closing Crack. Part 1. Available and Proposed Methods of Solution

The paper discusses the available analytical methods and the results of investigation of vibrations of elastic bodies with a bilinear asymmetric characteristic of restoring force that simulates the behavior of a local discontinuity in a material in the form of a closing fatigue crack. An approximate analytical method is put forward for the determination of vibrodiagnostic parameters of the vibration process of the nonlinear system under study in the range of weak superharmonic resonances.     

含裂纹平板的振动及裂纹扩展分析

针对含裂纹平板的振动与疲劳问题,研究含裂纹平板耦合动力学建模方法。首先在变形相似性原则下通过力学平衡原理推导出含裂纹项的平板振动方程,进而基于应力关系式形成裂纹项的表达式。在此基础上,利用Galerkin法将含裂纹板简化成单自由度振动系统,根据Berger经验方法产生方程的非线性项构建含裂纹板的非线性振动模型。最后通过算例探讨含裂纹板的动力学特性,协同Paris方程研究含裂纹平板动力学与裂纹扩展的耦合行为。研究结论表明,阻尼大小和激励力的变化对含裂纹板的振动特性及裂纹扩展规律具有显著影响。所提出的含裂纹平板耦合动力学建模方法,考虑了振动与裂纹扩展的耦合效应,为飞行器板结构抗振动疲劳设计提供理论依据。     

圆柱梁与水体耦联受迫谐振的解析解

本文分析了无粘性的、不可压缩水体中的弹性悬臂圆柱梁在水平地面简谐运动作用下的受迫振动,用直接求解梁与水体耦联的振动微分方程的方法,得到了动水压力和梁的动力反应的解析表达式.     

多跨连续长索的横振固有频率

采用LAPLACE变换求得了多跨连续长索固有横振振型的解析解,利用此振型解析解即可以方便地取得其固有横振的频率方程,并通过实例计算说明了该方法的应用。     

汽车动力吸振器优化设计

研究主要目的有二：其一,推导单动力吸振器和双动力吸振器解析解,建立吸振器数学模型;其二,建立动力吸振器设计方法,作为动力吸振器参数设计选用之依据。另一方面,根据吸振器数学模型,编写吸振器设计工具,并对吸振器质量、刚度和阻尼参数进行优化设计。最后,根据设计结果,试做汽车半轴合适之吸振器,并以实车进行测试。测试结果显示,安装试制吸振器后,实车振动噪声皆有显著改善。实用表明,利用吸振器解析解可快速对吸振器参数进行优化设计,避免传统吸振器数值仿真之繁复工作。     

任意跨弹性支承直梁横向自振的一个新解法

本文给出了任意跨弹性支承(包括扭转弹性支承)直梁横向自由振动的一个新解析解法,将弹性支承反力看作是作用于梁上的未知外力,求得了直梁横向受迫振动响应的解析解,由边界条件确定待定的积分常数,利用支承处支承反力与梁位移间的线性关系导出频率方程,频率方程是以阶数等于弹性支承个数的行列式表示的,振型函数则以统一的解析式表示,刚性支承是本文特例。本文具体导出了几种常见边界条件下的频率方程,最后给出了一个算例。     

受任意个同心弹性环支圆板横向自由振动的一个新的解析解法

本文研究受任意个同心弹性环支图板的横向自由振动问题,给出了一个新的解析解法。对弹性环支反力表示为作用于圆板上的待定外力,在求得圆板受迫振动的解析式后,由圆板的边界条件决定积分常数,利用环支处板位移与环支反力之间的线性关系得环支反力,并得频率方程。它是一阶数等于环支个数的行列式,可由行列式搜根法数值计算各阶固有频率,而振型函数则用一解析式表示,本文最后给出了一个算例,并与已有结果进行了比较。     

Spectroelectrochemical sensing based on attenuated total internal reflectance stripping voltammetry. 2. Determination of mercury and lead

Detection of lead and mercury by attenuated total internal reflectance spectroscopy coupled to stripping voltammetry is demonstrated. Changes in attenuation of light passing through an indium tin oxide optically transparent electrode (ITO-OTE) accompany the electrodeposition and stripping of lead and mercury on the electrode surface. The change in absorbance during stripping of electrodeposited metal constitutes the analytical response that enables detection over a range of 2.5 x 10(-7)-5 x 10(-5) and 5 x 10(-8)-5 x 10(-5) M for mercury and lead, respectively. The spectroelectrochemical responses of mercury and lead on the ITO surface are characterized and optimized with respect to solution conditions, the potential excitation signals used for deposition and stripping, and wavelength for detection. The deposited metals were examined by environmental scanning electron miscroscopy, and the electrodeposition pattern of lead and mercury was found to influence the optical response.     

考虑物料不对称滞回性质的振动压路机振动轮的动响应

考虑被压实物料的不对称滞回特性,建立了振动压路机振动轮-车架系统的二质量运动模型.通过解析分析,得到振动轮运动的近似解析式,并与实测的动响应进行了定性比较.证明了只有考虑参振物料的不对称滞回性质的影响,才能够得到正确的振动轮动响应.     

含裂纹悬臂梁的振动与疲劳耦合分析

基于Paris方程和同步分析方法考虑振动与疲劳裂纹扩展耦合之影响,提出一种含裂纹梁的振动疲劳寿命分析思路.振动分析过程中,利用线性弹簧等效裂纹段,复弹性模量引入阻尼损耗因子,得到考虑裂纹扩展、激励频率和阻尼等因素影响的动应力响应.结果表明:裂纹扩展、激励频率和阻尼等因素对疲劳寿命具有重要的影响.通过振动分析与疲劳裂纹扩展寿命估算同步进行,可进一步提高疲劳寿命估算精度.     

Vibrodiagnostic parameters of fatigue damage in rectangular plates. Part 3. Through-the-thickness and surface semi-elliptical cracks

The paper addresses the analytical determination of vibrodiagnostic parameters that describe the presence of normal-rupture flat through-the-thickness and surface semi-elliptical central cracks in a rectangular homogeneous plate of constant thickness for various plate fixing conditions and vibration modes. It is shown that the most sensitive vibrodiagnostic damage parameter of a plate is the variation of the logarithmic decrement in the case of a through-the thickness crack and the second-harmonic ratio of the vibration process in superharmonic resonance in the case of a surface crack. __________ Translated from Problemy Prochnosti, No. 5, pp. 27–47, September–October, 2006.     

复合材料纵横加筋圆柱壳自由振动分析

使用能力法分析了两端简支复合材料纵横加筋圆柱壳的自由振动特性,从Love’s理论出发,分别计算壳体面板和纵横加筋结构的应变能和动能,在计算加筋结构应变能和动能时,将加筋结构的作用影响平均在整个壳体区域。然后代入Lagrange方程得到频率方程。通过比较,计算方法所得到的结果与文献比较吻合。采用平均法计算的结果比采用离散方法计算的结果偏小。还研究了壳体和加筋结构参数的变化对圆柱壳自由振动频率的影响。     

Method of Validating the Measurement Accuracy When Estimating Circular Dispersion Parameters of Random Quantities

A formulation is given of the problem of an a priori estimation of the accuracy of linear measurements required in order to achieve a specified accuracy and reliability of determining the circular dispersion parameters of random quantities. An analytical solution of the problem is presented as applied to two types of distribution law for the measured quantities, Maxwellian and Rayleigh–Rice. The solution is illustrated by a numerical example.     

基于微粒群优化算法确定爆破测震参数

介绍了微粒群算法的基本理论,并把微粒群优化算法应用于爆破测震参数的计算中,结合实际工程,应用微粒群优化算法对爆破震动参数进行确定,得到了非常好的拟合效果.微粒群优化算法应用于爆破参数的确定是切实可行的.     

高效液相色谱法测定葡萄酒中苋菜红的不确定度评定

通过对高效液相色谱法测定葡萄酒中合成色素苋菜红质量浓度的全过程分析,确定了测定结果不确定度的来源。采用计量学不确定度传递模型,对引入的不确定度分量进行评定,确定了葡萄酒中苋菜红质量浓度标准不确定度由标准物质、标准溶液配制、标准曲线拟合、样品制备、测量重复性和回收率等6部分不确定度合成得到。2个不同质量浓度样品测定结果不确定度被评定,其相对扩展不确定度分别为2.6%和2.2%（k=2）,由不确定度评价结果分析得到,样品重复性测定和标准溶液配制是测定结果不确定度的主要来源。     

二维稳态热传导热源反问题LS-SVM解

本文研究了一类二维稳态热传导热源反问题．首先设置训练点集,将问题的近似解表示为与训练点集相关的高斯核函数组合的形式,然后依据最小二乘支持向量机原理优化参数．近似解由两部分组成,第一部分为满足边界条件的已知函数;第二部分为两项乘积,其中一项为在边界上为零的已知函数,另一项为含回归参数核函数线性组合形式．最后,通过两个有解析解的算例检验方法的有效性．结果表明了本文方法用于研究二维稳态热传导热源反问题的可行性．     

A Mixed-Approach Analysis of Deformations in Pipe Bends. Part 3. Calculation of Bend Axis Displacements by the Method of Initial Parameters

A problem of deformation of a curved shell loaded by internal pressure, axial force, and temperature difference is discussed. Physical equations are derived whereby the displacements and angles of rotation of the line of centers of mass of cross sections of a shell are related to loading parameters. A general constitutive set of equations for a curved element during its deformation is given. Using a method of initial parameters, an analytical solution is obtained for the differential equations for displacements and angles of rotation of the center line allowing for the action of distributed forces and moments.     

具有中间支承的正交异性矩形板自由振动分析

应用一般解析解来求解具有中间支承的正交异性矩形板的自由振动问题。一般解析解能求解任意边界条件矩形板的振动问题。求解过程是将整块板看成是沿中间支承分开的两块板。沿支承边两块板的挠度均等于零;斜度和弯矩均相等。由全部边界条件和连续性条件可以求解各阶频率和振型。对几种具有简支边、平夹边或自由边的板进行了计算。     

Estimation of the effects of plasticity and resulting crack closure during small fatigue crack growth

On the basis of a plastic-strip model and the method of singular integral equations, a closed-form analytical solution of the problem of an elastic-plastic plate containing a rectilinear fatigue crack is considered. The solution is used for the prediction of fatigue growth of `mechanically-small' crack by accounting for reverse plastic yielding and plasticity-induced crack closure in the material. The main effects of these factors on the crack-growth rate are analyzed, and the predicted results are compared with experimental data on small fatigue-crack growth in a aluminum-lithium alloy 2091-T351 and Fe-3% Si alloy.