500m3钢筋砼水塔承载力及动态刚度实例分析

针对一钢筋混凝土水塔实例,通过现场静态、动态参数测试,分析了钢筋混凝土水塔的承载能力及动态刚度,作出了科学诊断。     

刀具-工件接触动静刚度分析与计算研究

以回转体零件加工为例,考虑加工中变形及径向力的作用,对工件-刀具接触中动静刚度进行了分析与计算,提出了刚度系数的计算公式,并对其动态特性分析。结论与实验结果一致,从而为合理确定切削用量提供了一种途径。     

Impact of Modal Parameters on Milling Process Chatter Stability Lobes

1 Introduction Nowadays, millingis widely usedinfabricating of components of autos ,aircrafts , moulds and dies . Withthe rapid development of numerical control techniques ,the production efficiency and product quality are in theli melight . However ,as millingis anintermittent process ,a periodic forceinteracts betweenthe cuttingtool andworkpiece which makes the chatter vibration developed at specific conditions . This phenomenon may result in areduced productivity,increased cost andinconsist…     

所有顶点对之间最快路的算法

最快路是在最短的时间内把信息从源发送到目的端的路.该文采用标签设定算法,通过修改原网络,得到一个新网络,使得新网络中快速路的子路也是快速路.该文使用动态规划的方法,给出了所有顶点对之间最快路的算法.     

基于非结构嵌套网格的旋翼前飞流场计算

发展了一种基于线性弹簧理论的非结构动态嵌套网格方法,通过求解非定常Eu ler方程模拟了旋翼的前飞流场。根据距离参数快速生成便于计算的两个重叠网格子域,利用运动区子域网格的转动来模拟旋翼的旋转运动,并对其运用线性弹簧动态网格技术来处理旋翼的挥舞和变距运动。发展了一种快速查找插值贡献单元的方法,无需建立Inverse网格,提高了计算效率和精度。使用高效双时间方法分区求解非定常Eu ler方程,两个子域的流场参数在重叠区进行耦合。计算了旋翼的两种前飞状态,所得结果与实验和文献结果都很吻合。     

虚拟式动态应变测试仪

信号分析与处理是测试技术工作的重要组成部分,论述了一种自行开发的虚拟动态应变测试分析仪和信号分析功能的具体设计过程.实验测试表明仪器基本功能已经实现,信号分析结果正确,具有很好的工程应用性.     

薄壁箱型结构位移参数的动态Bayes随机估计

应用薄壁箱型结构的有限条控制方程,建立了薄壁箱型结构位移参数的动态B ayes误差函数和相应的动态B ayes均值及方差表达式.利用迭代步长的一维自动寻优方案,结合共轭梯度法研究了薄壁箱型结构位移参数的动态B ayes估计方法.通过典型算例分析,获得薄壁箱型结构位移参数先验信息准确性判定方法及结构位移参数动态B ayes随机估计的相关结论.     

A method of extending the dynamic range when transferring the dimensions of the unit of electrostatic field strength

Two equivalent methods of extending the dynamic range when transferring the dimensions of the unit of electrostatic field strength are proposed and analyzed. Both methods are based on the fact that the electrostatic field strength depends on the parameters of the electrostatic field generator and the position of the point of observation. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 49–51, May, 2006.     

Multidroplet Impact Model for Prediction of Residual Stresses in Water Jet Peening of Materials

In this article, a multidroplet impact model, proposed for predicting residual stresses induced on materials subjected to water jet peening, is presented. This approach considers the impact pressure distribution due to high-velocity droplets impinging on the material surface instead of stationary pressure distribution for prediction of residual stresses on water jet-peened surfaces. It makes use of Reichardt's theory for predicting the velocity distribution of droplets and liquid impact theory for predicting the impact pressure and duration of impact of high-velocity droplets. For predicting residual stresses on the surface and subsurface of material subjected to water jet peening, finite element modeling approach was adopted by using transient elastoplastic finite element analysis by considering an impingement of a set of droplets in succession to one another over a certain time period after which this pressure is released. The effectiveness of the proposed approach was demonstrated bv comparing the predicted residual stresses with those predicted by using the single set of droplets approach proposed by Rajesh et al. [6]. Finally, the practical relevance of the proposed approach was shown by comparing the predicted results with the experimental results obtained by water peening of 6063-T6 aluminium alloy.     

Dynamic Response Analysis of Fuzzy Stochastic Truss Structures under Fuzzy Stochastic Excitation

A novel method (Fuzzy factor method) is presented, which is used in the dynamic response analysis of fuzzy stochastic truss structures under fuzzy stochastic step loads. Considering the fuzzy randomness of structural physical parameters, geometric dimensions and the amplitudes of step loads simultaneously, fuzzy stochastic dynamic response of the truss structures is developed using the mode superposition method and fuzzy factor method. The fuzzy numerical characteristics of dynamic response are then obtained by using the random variable’s moment method and the algebra synthesis method. The influences of the fuzzy randomness of structural physical parameters, geometric dimensions and step load on the fuzzy randomness of the dynamic response are demonstrated via an engineering example, and Monte-Carlo method is used to simulate this example, verifying the feasibility and validity of the modeling and method given in this paper.