On the issue of investigating the strength of the IVV.10M reactor vessel and internals

The questions of strength and seismic stability of a new water-moderated water-cooled research reactor are examined. A computational method is developed and numerical investigation of static capacity and stability, brittle fracture resistance, long-term static capacity, long-term cyclic strength, and seismic load response is carried out. The most loaded parts in the reactor vessel and internals are identified, and quantitative estimates of the deflected mode parameters in risk areas are obtained. The results of calculations are compared with normative documents applicable in the domestic nuclear power industry. The equivalence of new design solutions to the requirements of reactor plant trouble-free operation during the life cycle not only under normal operating conditions but also in an extreme situation, in particular, by an earthquake, is proved.     

Variable heat flux in numerical simulation of grinding temperatures

In this paper, temperature results obtained by numerical simulations based on three different methods of defining the heat flux load distribution are compared to directly measured temperatures acquired using infrared camera measurement techniques. The heat flux calculations are based on recorded instantaneous grinding power, average grinding power, and power calculated by multiplying the measured tangential forces and the cutting velocity (referred to as calculated power). The results show that the method applied to characterize the input flux load in the numerical model has a significant effect on the estimated grinding temperatures and that the calculated power data produce the best temperature results.     

Specific features of operation of electrostatic microgenerators of energy

Specific features of operation of one- and two-capacitor microelectromechanical converters (MEMC) of energy of mechanical microscopic vibrations into electric energy with a modulated electrode-gap magnitude and with allowance for the mutual influence of electrical and elastic forces are analyzed, and the characteristics of these two devices are compared. The main factors restricting the increase in MEMC power are demonstrated to be the effects of “collapsing” and the condition of conservation of positive rigidity of the system. Expressions for estimating the limiting MEMC parameters are derived. The possibility of electrical energy generation in the presence of “real“ sources of wide-spectrum microscopic vibrations is considered.     

覆盖件模具拼接特征对球头刀铣削振动的影响

为了分析曲面拼接特征对振动的影响,建立了考虑拼接特征、曲面特征的未变形切屑厚度模型;基于曲面拼接区的未变形切屑厚度建立了考虑时滞变化的铣削动力学模型,通过数值计算综合分析了过拼接缝时冲击振动、刀具轴向位置角、拼接缝宽度对铣削振动的影响;最后基于淬硬钢曲面拼接铣削实验验证了考虑曲面拼接特征的铣削振动预测模型的准确性,并基于不同拼接特征下的铣削振动计算出了相应的加速度信号幅值和分形维数。研究结果表明:淬硬钢曲面拼接特征使铣削振动的非线性特征减弱,某一频段的振动能量集聚,据此情况可分析出不同拼接特征下的最佳加工工艺参数。     

Application of influence function method on the fretting wear of tube-to-plate contact

The structural integrity of steam generators in nuclear power plants is much dependent on the fretting wear characteristics of Inconel 690 U-tubes. The influence function method for the tube-to-plate contact model is demonstrated in this study to investigate the fretting wear problems on the secondary side of the steam generator, which are caused by flow induced vibrations between the U-tubes and supports. Two-dimensional numerical contact model is developed and formulated in terms of the Cauchy singular integral equation. The distributions of normal pressures, shear stresses and displacement fields are derived between two contact bodies which have similar elastic properties. Based on the algorithms for normal pressures and relative slip, a numerical approach is developed to simulate the fretting wear of tube-to-plate contacts. The work rate model is adopted in this study to find the wear amounts between two materials. The results are compared with the solutions by finite element analyses to validate the application of the present method to fretting wear problems.     

Experimental study on the energy flow analysis of underwater vibration for the reinforced cylindrical structure

Energy flow analysis (EFA) can be used effectively to predict structural vibration in the medium-to-high frequency ranges. In this study, the energy flow finite element method (EFFEM), based on EFA, was used to predict the vibrations of a reinforced cylindrical structure in water. The predicted results of the vibrational energy density for the structure were compared with corresponding experimental results. The structure was divided into several subsystems in the experiment, with several accelerometers attached to each subsystem. The input power excited into the experimental structure was measured using an impedance-head adhered to an exciter. Measured input power was used to predict vibration of the reinforced cylindrical structure by EFFEM in water for comparing experimental and numerical results. A comparison between the experimental and predicted results for the vibrational energy density showed that EFFEM was an effective tool for predicting structural vibration.     

Investigation on Mesh and Sideband Vibrations of Helical Planetary Ring Gear Using Structure,Excitation and Deformation Symmetries

Time?variant excitations in planetary gear trains can cause excessive noise and vibration and even damage the system on a permanent basis. This paper focuses on the elastic vibrations of a helical planetary ring gear subjected to mesh and planet?pass excitations. Motivated by the structure, excitation and deformation symmetries, this paper proposes dual?frequency superposition and modulation methods to capture the mesh and sideband vibrations. The transi?tion between ring gear tooth and planet is introduced to address the excitations and vibrations. The phasing e ect of ring gear tooth and planet on various deformations is formulated. The inherent connections between the two types of vibrations are identified. The vibrations share identical exciting rules and the wavenumber and modulating signal order both equal the linear combination of tooth and planet counts. The results cover in?plane bending and extensional, out?of?plane bending and torsional deformations. Main findings are verified by numerical calculation and comparisons with the open literature. The analytical expressions can be used to determine whether the sideband is caused by component fault or only by elastic vibration. The methods can be extended to other power?transmission systems because little restriction is imposed during the analysis.     

基于微液滴介质和差分电容器的静电式微型振动发电机

针对现有悬臂梁式微型振动发电机存在低频响应不敏感,抗冲击能力差等问题,提出了一种利用微液滴介质拾振实现差分电容器变化及电荷转移的静电式微型振动发电机新结构.根据驻极体模型,推导出了差分电容器极板的电荷分布公式;结合微液滴作受迫正弦振动假设,建立了静电式微型振动发电机的数学模型.采用COMSOL Multiphysics软件对微液滴运动及电容器极板电荷分布进行了仿真,得到了发电机的输出电压幅频特性.制作出了以汞为介质的静电式微型振动发电机样机,进行了样机的性能测试.实验结果表明:该静电式微型振动发电机共振频率为3 Hz,在加速度为3 9、振动激励频率为3 Hz,负载为1 MΩ时,测得样机输出电压峰-峰值为1.21V,输出功率为0.73 μW,实现了环境中低频振动能量的获取与转换.     

直动型溢流阀的流固耦合建模与动态特性研究

直动型溢流阀被广泛用于水下动力设备的供能调节,但下潜水深的变化时常使得其动态稳定性无法保证,以至于在到达一定水深之后,溢流阀阀口会出现异常的压力波动现象,影响其正常的工作状态。为此,开展流固耦合分析,建立了直动型溢流阀的两自由度动力学模型。通过无因次化后模型的求解,实现了对试验测试信号中振动深度的准确复现,并进一步分析了溢流阀阀芯的轴向和纵向振动状态随水深的变化,以及在部分深度下阀芯振动的多稳态共存现象。所建立的动力学模型中的非线性因素为试验测试信号中发现的压力波动特征提供了理论解释,从而为通过对溢流阀的优化设计来解决溢流阀的大振幅脉冲振动提供了模型支撑。     

Numerical and experimental analysis of coupled transverse and longitudinal vibration of a marine propulsion shaft

An appropriate assessment of the dynamic behavior of marine propulsion shaft in ships is essential to enable optional delivery of power to the propeller and to minimize unnecessary vibration. Various vibrations coupling with each other can significantly influence the dynamical behavior of the shaft and threaten the reliability of ships. This paper presents a finite element analysis model with multiple constraint conditions to analyze the coupled transverse and longitudinal vibrations of a marine propulsion shaft. Based on this model, in addition to the coupled natural frequencies of each direction, the maximum acceleration are also determined. Furthermore, the simulation of an idling and loading vibration analysis is discussed and validated against experimental results, over a range of rotational speeds. The output of numerical simulation is found to agree with the corresponding results from experimental tests. Finally, an accurate and applicative FEA model for coupled transverse-longitudinal vibration of shaft has been obtained.     

Electrostatic microgenerators of energy with a high specific power

Operation regimes of an electrical energy microgenerator based on a multilayered structure consisting of a metal, a dielectric with a built-in charge, a microgap, and a moving electrode, whose operation principle is based on electrode vibrations in the force field of the space charge of the dielectric, are analyzed. Specific features of electromechanical conversion of energy due to vibrations of the electrode surface in submicron gaps are found. It is demonstrated that such microgenerators in the low-frequency regime (10–100 Hz) can produce power sufficient for providing energy for modern microcircuits (up to 1–10 mW/cm²) without using any other power sources.     

Dynamic analysis of fiber-reinforced elastomeric isolation structures

This paper presents an analysis of seismically isolated buildings using fiber-reinforced elastomeric structures that are subject to excitations caused by earthquakes. In analyzing the vibrations, the buildings are modeled by lumped mass systems. The fundamental equations of motion are derived for base isolated structures, and the hysteretic and nonlinear- elastic characteristics are included in the numerical calculations. The earthquake waves used as the excitation forces are those that have been recorded during strong earthquake motions in order to examine the dynamic stability of building structures. The seismic (nonlinear) responses of the building are compared for each restoring force type and, as a result, it is shown that the building’s motions are not so large from a seismic design standpoint. Isolating structures are shown to reduce the responses sufficiently allowing the building’s motions to be controlled to within a practical range. By increasing the acceleration of the earthquake, the yielding forces in the concrete and steel frames can be determined, which shows the advantages of performing nonlinear dynamic analysis in such applications. This paper was recommended for publication in revised form by Associate Editor Dae-Eun Kim Gyung-Ju Kang received a B.S., M.S. and Ph.D degrees in Aerospace Engineering from Pusan National Univer-sity, Korea, in 1997, 1999 and 2005, respectively. Dr. Kang’s research interests are in the area of seismic bearing design, base isolation, cold forging, and steel structure. Beom-Soo Kang received a B.S. degree in Mechanical Engineering from Pusan National University, Busan, Korea in 1981. He then went on to receive his M.S. degree in Aerospace Engineering from KAIST (Korea Advanced Institute of Science and Technology) Seoul, Korea, in 1983 and Ph.D. degree in Mechanical Engineering from University of California at Berkeley in 1990. Dr. Kang is currently a Professor at Department of Aero-space Engineering at Pusan National University. He is currently serving as the Director of ILIC (Industrial Liaison Innovation Cluster). Dr. Kang’s re-search interests include flexible forming, unmanned system design, multi-stage deep drawing, and cold forging.     

滑动摩擦振动噪声的非线性显式动力学分析

利用有限元软件ABAQUS/Explicit(显式动态求解器)对球-平面接触条件下的滑动摩擦振动噪声进行了数值模拟分析。对比试验结果,探讨了摩擦噪声的发生机制,并分析了摩擦噪声发生时接触界面的运动特性。结果表明,摩擦噪声主要是由摩擦系统的自激振动引起的,法向振动与切向振动的耦合是系统产生自激振动和摩擦噪声的一个重要因素。当摩擦系统发生自激振动时,从面节点与主面的接触并不是连续不变的,两者在相对运动的过程中具有黏着-滑动-分离-黏着的特性。     

Stability of laminated rubber bearing and its application to seismic isolation

In this paper, the effects of shape factors on the buckling loads in the laminated rubber bearing (LRB) are investigated to guide the design of LRB in determination of the rubber plate thickness and the total rubber height. To substantiate the application of LRB to the seismic isolation of nuclear power plants, the seismic analyses and shaking table tests are carried out for a seismically isolated structure using four LRBs. The parameter equations of seismic isolation frequency are obtained from the shaking table tests and the quasi-static tests of LRB itself to investigate the effects of the LRB characteristics in prediction of maximum peak acceleration responses by analysis. From the comparison of the maximum peak acceleration responses obtained from numerical analyses and experiments, it is verified that the horizontal stiffness variations of LRB should be considered in seismic analysis to get more accurate results.     

隔震结构的地震响应时程分析

建筑物在地震作用下的动力响应时程分析一直是非常复杂和计算量很大的问题。对于隔震结构,由于隔震层参数与上部结构参数相差较大,容易导致数值病态。为了准确计算隔震结构的地震响应,本文放弃了传统求解动力方程常用的差分格式,而是把二阶结构动力方程通过增维、降阶转化为一阶微分方程组,然后利用精细积分法对其求解;对杜哈梅尔积分项采用牛顿-柯特斯公式及相应的复化公式进行数值计算;考虑建筑物地震作用力—等效惯性力的特点,实现其简化计算,节约计算时间;插值点间隔为地震波的取样时间,确保地震作用大小无插值误差。本文算法避免矩阵求逆,提高了计算效率,数值算例显示了算法的有效性和效率。     

Numerical investigation of an Organic Rankine cycle radial inflow two-stage turbine

The Organic Rankine cycle power plants have recently been the subject of intensive and remarkable growth in research worldwide. The system operates using very impressive technology to convert low to moderate heat sources into useful electrical power by means of a turbine. It offers the advantages of better operating performance, less crowded components compared to the classical steam and gas power plants for low power ranges, and more importantly, no greenhouse gas effects on the atmosphere. Numerical investigations of the turbine play a major role in improving the performance of the system, and an accurate CFD simulation interfaced with accurate thermodynamic models is considered a significant step in the design and prediction of the turbine performance. This paper draws both numerical and experimental performance maps of an ORC radial inflow two-stage turbine, starting with experimental data collection and refinement, passing by the performance parameters calculation. A commercial CFD tool was used to study the grid-independency of the numerical performance maps; a medium and fine mesh were generated and checked against the experiments. The look-up-tables interpolation method was implemented in this study to evaluate the working fluid thermodynamic properties. The main objective of this work is the validation and improvement of the numerical model prediction with respect to the experimental results.     

Quasi-optimal processing of laser Doppler vibrometer signals

A method of quasi-optimal processing of laser Doppler vibrometer (LDV) signals in the case of monoharmonic vibrations is considered. Under certain assumptions, the problem of quasi-optimal estimation of the information parameter of the LDV signal, related through a known constant multiplier to the relative amplitude of vibrations, is solved. A structure of the device for optimal estimation is proposed. Conditions of optimality of the method are given. Statistical characteristics of estimates of the relative vibration amplitude are investigated by a numerical modeling method. The error of these estimates is compared with the Rao-Kramer bounds.     

Finite element model of the contact between a vibrating conductor and a suspension clamp

Aeolian vibrations may lead to failure of the overhead conductors of electrical transmission lines. Damages are caused by fretting fatigue at the attachment position of pieces of hardware. This phenomenon depends much on contact mechanics. The contact between a wire and a suspension clamp, a critical location, was modelled using the finite element method. Results from strain measurements on vibrating conductors served as input. The numerical results gave estimates of stresses and slip amplitudes. We can use these results to compute crack initiation criteria. The Ruiz and Chen criterion was chosen here and results compared well with experimental data.     

Loading rate effects of high damping seismic isolation rubber bearing on earthquake responses

This paper investigates the effects of the loading rates of high damping seismic isolation rubber bearing on earthquake responses. For this purpose, a seismically isolated system is formulated by the Runge-Kutta numerical algorithm with nonlinear rate model of high damping rubber bearing to carry out the seismic time history response analysis. Results, of the seismic time history response analyses using both the present parameter equations and Fujita's equations are compared with those of pseudo dynamic tests. From these results it is confirmed that the parameter equations of high damping rubber bearing should be obtained by tests with the loading rate equivalent to the isolation frequency as close as possible.     

Dynamic modeling, input-shaped maneuvering and vibration suppression of flexible body using quasi-coordinates and euler parameters

In dealing with the dynamics of a flexible body, the rigid-body motions and elastic vibrations are analyzed separately. However, rigidbody motions cause vibrations, and elastic vibrations affect rigid-body motions, indicating the inherent coupling between rigid-body motions and elastic vibrations. The coupled equations of motion for a flexible body can be derived by means of Lagrange’s equations in terms of quasi-coordinates. The resulting equations of motion are hybrid and nonlinear. This paper proposes a unified approach for the equations of motion for a flexible body based on the perturbation method and the Lagrange’s equations of motion in terms of quasicoordinates and Euler parameters to analyze a more general case maneuvering. The resulting equations consist of zero-order nonlinear equations of motion which depict rigid-body motions and first-order time-varying linear equations of motion which depict perturbed rigid-body motions and elastic vibration. Hence, the input-shaped maneuvering can be applied to the zero-order equation considering the induced vibrations. Since the input-shaped maneuvering alone cannot achieve vibration suppression, the vibration suppression controller combined with the input-shaped maneuvering is proposed in this study. As a numerical example, a hub with elastic appendages is considered. Numerical results show that the unified modeling approach proposed in this paper is effective in numerical simulation and control design.