共查询到20条相似文献,搜索用时 836 毫秒
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本文提出一种对动力学问题的Hamilton正则方程进行正则变换的方法,并给出一种沿时间方向迭代,沿空间方向半离散半解析求解动力问题Hamilton正则方程的方法──混合状态Hamiltonian动力元. 相似文献
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本文运用广义函数论理δ函数的导数,推演得到了厚板动力影响系数,考虑厚板材料具有强化行为,利用已知弹性解进行厚板弹塑性动力分析,对任意荷载作用下的矩形厚板的弹塑性动力响应出解的一般表达式,文中以四边简支矩形板为例给出了数值结果,对按改进理论和经典理论所预示的结果进行了比较,本文方法可以厚板与连续介质共同作用的场合。 相似文献
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本文运用广义函数论处理δ函数的导数,对集中力作用下的厚板进行动力分析。基本方程采用由本文作者推演得到的改进的Donnell厚板振动方程。用样条配点法求解广义坐标,对集中力作用下的厚板弹性动力响应给出解的一般表达式。文中以能形板为例给出了数值结果,对按改进理论和经典理论所预示的结果进行了比较。本文方法可以用于厚板物理非线性和几何非线性动力分析和厚板与连续介质共同作用的场合,文中给出了有关表达式。 相似文献
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基于状态空间理论的结构动力响应解法 总被引:7,自引:2,他引:5
本文基于状态空间理论分析结构动力响应问题,根据结构动力学方程,引入系统的状态变量,建立状态方程,并给出了非奇次状态方程的解,对于求解矩阵指数函数有多种解法。文中着重介绍凯莱-哈密尔顿法。状态空间迭代法和精细积分法,对结构动力响应问题按三种解法分别建立了计算格式,并编制相应程序,文末给出了数值算例,其计算结果表明,状态空间法分析结构动力响应,其精度好效率高,是一种有非常有效的方法。 相似文献
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Hamilton体系下的变分原理和半解析有限元解 总被引:3,自引:0,他引:3
本文通过讨论弹性力学几种主要变分原理在Hamilton体系下的表现形式,得出了在Hamilton体系下几种变分原理等价和相应泛函分为两类的结论,求出了基于两类泛函基础上的单元半解析解,并对单元性能进行了讨论。 相似文献
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智能桁架机电偶合动力分析与振动控制 总被引:2,自引:0,他引:2
把作为主动杆全部或部分的压电陶瓷作动/检测元件视为多层迭合体,从机电耦合弹性理论出发,利用Hamilton原理建立了智能桁架机构机电耦合有限元动力分析模型,可用于机械/电载荷共同作用下的结构静/动力分析和振动控制系统设计。同时给出了元件的作动/检测方程,并以压电作动元件输入电压作为控制量,利用结构状态空间方程进行振动系统最优反馈控制律设计。算例表明该分析方法最可行的。 相似文献
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本文基于Reissner理论求解矩形厚板的弯曲问题,给出在任意一点作用集中荷载与矩形厚板弯曲问题的解析解,并给出了具有实际价值的计算结果。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di... 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献