Experimental investigation and analytically modeling of hysteretic behavior of rigid bus-flexible connectors of 220 kV electrical substations

This paper describes the quasi-static testing and analytical modelling of the hysteretic behavior of aluminum alloy rigid bus-flexible connectors of 220 kV electrical substations.The main objective of the study is to experimentally investigate the hysteretic behavior of six different types of rigid bus-flexible connectors 220 kV electrical substations when subjected to cyclic loading.Another objective is to theoretically study the flexibility and effectiveness of a previously proposed analytical model in fitting the experimental hysteresis loops of the tested rigid bus-flexible connectors.The experimental investigation indicates that the tested rigid bus-flexible connectors exhibit highly asymmetric hysteresis behavior along with tension stiffening effect.The theoretical study demonstrates that the generalized Bouc-Wen model has high flexibility and is effective in fitting the experimental hysteresis resisting force-displacement curves of the six tested rigid bus-flexible connectors.

Determination of Material Parameters of EVA Foam under Uniaxial Compressive Testing Using Hyperelastic Models

The objective of this research was to determine the mechanical parameter from EVA foam and also investigate its behavior by using Blatz-Ko,Neo-Hookean,Mooney model and experimental test.The physical characteristic of EVA foam was also evaluated by scanning electron microscopy(SEM).The results show that Blatz-Ko and Neo-Hookean model can fit the curve at 5%and 8%strain,respectively.The Mooney model can fit the curve at 50%strain.The modulus of rigidity evaluated from Mooney model is 0.0814±0.0027 MPa.The structure of EVA foam from SEM image shows that EVA structure is a closed cell with homogeneous porous structure.From the result,it is found that Mooney model can adjust the data better than other models.This model can be applied for mechanical response prediction of EVA foam and also for reference value in engineering application.

Analytical models for the penetration of semi-infinite targets by rigid,deformable and erosive long rods

A theoretical study is presented herein on the pen- etration of a semi-infinite target by a spherical-headed long rod for Yp 〉 S, where Yp is the penetrator strength and S is the static target resistance. For Yp 〉 S, depending upon initial impact velocity, there exist three types of penetration, namely, penetration by a rigid long rod, penetration by a deforming non-erosive long rod and penetration by an erosive long rod. If the impact velocity of the penetrator is higher than the hydrodynamic velocity （VH）, it will penetrate the target in an erosive mode; if the impact velocity lies between the hydrodynamic velocity （VH） and the rigid body velocity （VR）, it will penetrate the target in a deformable mode; if the impact velocity is less than the rigid body velocity （VR）, it will penetrate the target in a rigid mode. The critical conditions for the transition among these three penetration modes are proposed. It is demonstrated that the present model predictions correlate well with the experimental observations in terms of depth of penetration （DOP） and the critical transition conditions.

Dynamic model for landsliding monitoring under rigid body assumption

Based on the assumption that the slope bodies are rigid, the dynamic model of the landsiding (forward model) was put forward. According to the dynamic model, the system equations of Kalman filter were constituted. The mechanical status of a slope was hence combined with the monitoring data by Kalman filter. The model uncertainties or model errors could also be considered through some fictitious observation equations. Different from existed methods, the presented method can make use for not only the statistic information contained in the data but also the information provided by the mechanical and geological aspect of slopes. At last a numerical example was given out to show the feasibility of the method. [

A 3-DOF Pseudo-Rigid-Body Model for Tension-Based Compliant Bistable Mechanisms

Compliant bistable mechanisms, devices with two distinct stable equilibrium positions, are used in a variety of applications, such as switches, clasps, and valves. Many kinds of compliant bistable mechanisms were proposed and studied during the past decade. Among them, tension-based compliant bistable mechanisms, that incorporate tension pivots as their flexible members, feature in short travel distance and low power consuming. So far, the design of this kind of bistable mechanisms is done using finite element method through trial and error, thus is time-consuming. By treating the tension pivots as fixed-guided segments and their elongation as a spring, we developed a novel three degree-of-freedom （3-DOF） pseudo-rigid-body model （PRBM） for this kind of bistable mechanisms. The principle of virtual work is used to derive the force-deflection relationship of the PRBM model. The comparison between the PRBM results and the experimental results of the force-deflection characteristics shows that the PRBM can predict not only the bistable behavior of the tension-based bistable mechanisms, but also their soft spring-like post-bistable behavior and the spring-like force-deflection characteristics when pulling in the reverse direction from the as-fabricated position, which is called reverse behavior. The 3-DOF PRBM can be used to design and identify tension-based bistable mechanisms. Using the PRBM instead of the trial-and-error method can greatly reduce the development time of this kind of bistable mechanisms.

THE MODEL TEST RESEARCH OF HORIZONTAL FORCE ON RIGID SHAFT FURNITURE IN DEEP MINE

The state of deep mine rigid shaft fUrniture horizontal force calculation in China is introduced and the calculating model of horizontal force is determined. Based on the interaction between hoisting vessel and shaft furniture, the vertical mobel test device is built and a large number of model tests and analyses are carried out. At last, the relationship between horizontal force and hoisting end load, hoisting speed or bunton level interval is gained. The three parameters horizontal force calculating equation of beep mine rigid shaft furniture is given and it can guide the design and calculation of shaft engineering.

Alternating Parity Band in Octupole-Soft ^(140)Xe with Axial Vibrational-Rotational Model and Triaxial Rigid Rotor Model

Energies of the yrast positive-and negative-parity excited states in140 Xe are reproduced by two different models considering quadrupole-octupole deformations, namely the axial vibrational-rotational model and the triaxial rigid rotor model, and compared with the stable octupole-deformed222 Th. The origin of the energy difference between the opposite parity sequences is considered from two different mechanisms, the vibration in axial deformed energy minima and the rotation considering the effective triaxial deformation. The success of reproducing the data in both the models implies that these two mechanisms are equivalent on some level for the octupole-soft nuclei. By investigating the probability distributions for projection of total angular momentum in the triaxial rigid rotor model, it is found that such an energy difference is associated with the difference of orientation of the rotational axis.

Quasi-Radial Modes of Pulsating Neutron Stars: Numerical Results for General-Relativistic Rigidly Rotating Polytropic Models

In this paper we compute general-relativistic polytropic models simulating rigidly rotating, pulsating neutron stars. These relativistic compact objects, with a radius of ~10 km and mass between ~1.4 and 3.2 solar masses, are closely related to pulsars. We emphasize on computing the change in the pulsation eigenfrequencies owing to a rigid rotation, which, in turn, is a decisive issue for studying stability of such objects. In our computations, we keep rotational perturbation terms of up to second order in the angular velocity.

Reverse Monte Carlo Modeling of the Rigidity Percolation Threshold in Ge<SUB>x</SUB>Se<SUB>1-x</SUB>Glassy Networks

Based on Maxwell’s constraint counting theory, rigidity percolation in GexSe1-x glasses occurs when the mean coordination number reaches the value of 2.4. This corresponds to Ge0.20Se0.80 glass. At this composition, the number of constraints experienced by an atom equals the number of degrees of freedom in three dimensions. Hence, at this composition, the network changes from a floppy phase to a rigid phase, and rigidity starts to percolate. In this work, we use reverse Monte Carlo (RMC) modeling to model the structure of Ge0.20Se0.80 glass by simulating its experimental total atomic pair distribution function (PDF) obtained via high energy synchrotron radiation. A three-dimensional configuration of 2836 atoms was obtained, from which we extracted the partial atomic pair distribution functions associated with Ge-Ge, Ge-Se and Se-Se real space correlations that are hard to extract experimentally from total scattering methods. Bond angle distributions, coordination numbers, mean coordination numbers and the number of floppy modes were also extracted and discussed. More structural insights about network topology at this composition were illustrated. The results indicate that in Ge0.20Se0.80 glass, Ge atoms break up and cross-link the Se chain structure, and form structural units that are four-fold coordinated (the GeSe4 tetrahedra). These tetrahedra form the basic building block and are connected via shared Se atoms or short Se chains. The extent of the intermediate ranged oscillations in real space (as extracted from the width of the first sharp diffraction peak) was found to be around 19.6 ?. The bonding schemes in this glass are consistent with the so-called “8-N” rule and can be interpreted in terms of a chemically ordered network model.

Kinematic simulation of human gait with a multi-rigid-body foot model

The paper builds a multi-rigid-body model of human with a 4-rigid-body foot in the 3D CAD software Solidworks, based on human anatomy. By controlling the rotation of the ankle and major joints of human body while walking, the Kinematic simulation was performed in the dynamics simulation software ADAMS. The paper analyzes the simulate results and points out deficiencies in the current work and the direction of research efforts in future.

A DYNAMIC MODEL FOR ROCKET LAUNCHER WITHCOUPLED RIGID AND FLEXIBLE MOTION

The dynamics of a coupled rigid-flexible rocket launcher is reported. The coupled rigid-flexible rocket launcher is divided into two subsystems, one is a system of rigid bodies, the other a flexible launch tube which can undergo large overall motions spatially. First, the mathematical models for these two subsystems were established respectively. Then the dynamic model for the whole system was obtained by considering the coupling effect between these two subsystems. The approach, which divides a complex system into several simple subsystems first and then obtains the dynamic model for the whole system via combining the existing dynamic models for simple subsystems, can make the modeling procedure efficient and convenient.

STATISTICAL MODELS FOR SEMI-RIGID NEMATIC POLYMERS

Semi-rigid liquid crystal polymer is a class of liquid crystal polymers different from long rigid rod liquid crystal polymer to which the well-known Onsager and Flory theories are applied. In this paper, three statistical models for the semi-rigid nematic polymer were addressed. They are the elastically jointed rod model, worm-like chain model, and non-homogeneous chain model. The nematic-isotropic transition temperature was examined. The pseudo-second transition temperature is expressed analytically. Comparisons with the experiments were made and the agreements were found.

基于特性的牵引车-半挂车刚柔组合车架动力学模型研究

商用车较大的车架柔性会影响到整车的操纵稳定性和乘坐舒适性,尤其是在共振时车架柔性会放大对车辆运动品质的影响。为实时模拟牵引车-半挂车的车架运动,采用基于总成特性的建模技术路线,根据运动响应频域将车架运动解耦为低频刚体运动和高频柔体运动,并将车架模型模块化划分为基于多体动力学的刚体车架模块、基于模态综合法的柔体车架模块,然后将两模块求解结果叠加形成刚柔组合车架模型。最后,将车架模型嵌入牵引车89DOF-半挂车73DOF整车模型中,针对某款商用车进行仿真,通过对比实车场地试验结果,验证了模型的有效性。

Non-rigid 3D models retrieval based on hierarchical matching

In 3D models retrieval, feature description and retrieval of non-rigid model face more complex problems due to the isometry transformation of itself. We introduce the hierarchical combination matching into the feature comparison, and build a map between the divided regions of two models, and then achieve accurate feature matching based on patch-by-patch, which successfully introduces the spatial information into feature matching. Verified by experiment, the 3D model retrieval method proposed in this paper based on hierarchical combination matching can make sure more accurate feature matching, so as to enhance the precision of retrieval.

多簧片结构的磁保持继电器多物理场刚柔耦合仿真模型建立和实验分析

多簧片结构的磁保持继电器衔铁转动引起的触点碰撞、弹跳现象使运动过程复杂,静、动态特性理论分析和仿真模型建立困难。以某型号多簧片结构的磁保持继电器为研究对象,理论分析结构拓扑及工作机理,考虑触点间切入深度,引入狄拉克函数和赫维赛德函数,解决簧片受力分散及触点由于碰撞、弹跳引起的作用力不连续问题;将簧片等效为悬臂梁,基于欧拉-伯努利梁理论建立触簧系统三簧片分段耦合动力学模型。利用Ansys Maxwell引入基于误差的自适应网格划分方法求解电磁机构静态特性;考虑触簧系统簧片运动变形效应,通过ADAMS基于模态理论,构建刚柔耦合动力学仿真模型。基于分段动力学思想,搭建电-磁-机械运动多物理场刚柔耦合仿真模型。利用高速摄像机、电流探头等设计磁保持继电器实验方案,搭建实验平台,测试并分析磁保持继电器触点吸合运动时间、触点压力、弹跳时间、线圈电流,并分析人工装配簧片引起触点压力不同使继电器动作过程存在的不一致性问题,验证该文所提多簧片结构的磁保持继电器特性分段耦合分析方法和多物理场刚柔耦合仿真模型的有效性。

Voronoi-RBSM耦合的混凝土细观建模方法研究

为解决已有混凝土细观数值模拟方法计算效率低、对象尺寸受限的问题,提出一种基于Voronoi网格拓扑和刚体弹簧模型(RBSM)的混凝土细观建模新思路。该模型将混凝土视为由骨料、水泥砂浆组成的二相材料,骨料通过Voronoi单胞描述,视为刚性体,水泥砂浆简化为Voronoi单胞交界面的均布弹簧,弹簧刚度依据局部砂浆的实际情况自动定义。无需对骨料和水泥砂浆进行网格细化,可大大减少单元数量,允许Voronoi单胞在界面处侵入和分离,描述混凝土的变形、开裂等。为验证该文模型的有效性和适用性,开展了室内试验与数值模拟的对比研究,并分析了骨料占比等参数的敏感性。结果表明:基于Voronoi-RBSM的混凝土细观模型,可以较为高效、准确预测混凝土构件在加载过程中细观力学响应,对于尺寸较小的混凝土试件、尺寸较大钢筋混凝土简支梁均有较好的细观模拟效果,尤其是当网格尺寸与骨料平均粒径接近时,预测结果与试验结果最为接近。此外,模型的预测精度受骨料体积占比影响,骨料体积占比越小精度越低,因此,并不适用于浆体占比高的混凝土材料细观数值模拟。

空间连杆引纬机构的刚柔耦合磨损分析

为准确预测空间连杆引纬机构间隙磨损机制,通过结合Lankarani-Nikravesh与Bai碰撞力模型,建立可变刚度与阻尼系数非连续接触碰撞力模型,采用改进的Coulomb摩擦力模型描述含间隙机构旋转铰的切向摩擦力,通过Lagrange方法对系统动力学建模;其次选取空间连杆为柔性化对象,综合Ansys与Adams分析,对空间连杆引纬机构进行刚柔耦合动力学仿真;最后将系统的动态仿真响应结果与Archard模型相结合,求解运动副磨损情况。结果表明:柔性构件可以有效缓解机构间隙碰撞的冲击作用,间隙为0.15 mm条件下,剑头加速度振荡最大幅值缩减53.2%;当间隙升至0.5 mm后,虽磨损范围大幅增加,但间隙磨损深度并未随之大幅提升。

不同倾斜方式对倾斜液化场地地震响应的影响分析

在倾斜场地地震液化后,土体的侧向流动扩展引起的场地失效以及大变形问题的研究中,不同的倾斜方式会对试验结果产生一定的影响,而目前针对不同倾斜方式对倾斜液化场地土体地震动力响应影响评价的研究成果还较为少见。根据课题组开展的水平液化自由场振动台试验,首先基于OpenSees有限元平台建立了水平液化自由场有限元计算模型,在数值模型中考虑了模型箱对场地土地震响应的影响,通过对比数值计算结果与试验结果验证了数值模型的可靠性。在此基础上建立了倾斜液化自由场有限元计算模型,分别建立了层剪箱整体倾斜模型、层剪箱场地土倾斜模型和刚性箱场地土倾斜3种不同的数值模型来模拟振动台试验中采用的不同的倾斜方式。通过对比,分析了在0.3g汶川地震卧龙波作用下3个数值模型计算得到的自由场土体动力响应结果,并讨论了3种不同的倾斜方式对计算结果的影响,最后给出了针对倾斜液化场地地震动力响应数值模拟和振动台试验研究中的一些有参考价值的结论。

基于刚柔耦合模型的黄鳝剖切机仿真及试验

针对目前黄鳝人工剖切费时、费力且安全性差等难点,该研究以体表黏滑的鲜活黄鳝为研究对象,设计了一款小型黄鳝自动剖切机。首先,测定了黄鳝基本物理参数以及相关力学参数。其次,基于刚柔耦合原理,将黄鳝鱼体与夹持轮、滑道的接触等效为刚度—阻尼模型,运用Abaqus与Adams仿真软件建立其刚柔耦合模型。以鱼体输送时间、输出速度、夹持力、整机振动为试验指标,探究弹簧刚度、滑道倾角、夹持轮转速等单因素对试验指标的影响。结果表明,随着弹簧刚度增大,夹持力先增大后降低,整机振动幅度降低,而输送时间和输出速度影响不大。随着滑道倾角增大,鱼体输出时间减少,而输出速度、夹持力、整机振动增大。随着夹持轮转速的增大,鱼体输送时间、输出速度、夹持力、整机振动均增大。在单因素分析基础上进行多因素分析,获得优化工况为夹持轮转速600 r/min、弹簧刚度1.2×10^(3) N/m、滑道倾角16°。最后,开展黄鳝自动剖切机加工试验,测得的振动参数以及鱼体输出速度与仿真结果接近,且鲜活黄鳝在优化工况下剖切效果良好。研究结果为小型黄鳝剖切机设计提供参考。

模块化建筑刚性桩复合地基共同作用试验分析

本文依据某模块化示范楼,制作了简化后的1∶10的模块化建筑刚性桩复合地基的室外缩尺模型,考虑了上部模块结构与地基基础共同作用。通过模型试验分析了上部模块刚度变化对上部模块钢柱、筏板基础和刚性桩复合地基各受力体的影响。结果表明:模块化建筑中部柱轴力>边部柱轴力>角部柱轴力;随上部模块刚度的增加,中部柱轴力逐渐减小,边部柱和角部柱轴力逐渐增大;筏板基础中部沉降最大,边部沉降最小,整体沉降随上部模块楼层的增加逐渐增大;角部桩身轴力>边部桩身轴力>中部桩身轴力,桩身轴力沿着桩深度方向先增大后减小;桩身上部一定范围内产生负摩阻力。分析结果能够为模块化建筑单元构件设计及刚性桩复合地基基础优化设计提供参考。