拉弯荷载下钢管杆塔内外法兰设计计算方法

针对内外法兰在拉弯荷载下的力学行为及承载力计算方法进行研究。基于平截面假定推导了半解析计算方法,并将该方法的计算结果与非线性有限元分析结果进行了比较验证。通过研究旋转轴、中性轴和承载力随轴向拉力变化,揭示了其在拉弯荷载下的受力特征。最后对一系列内外法兰的承载力进行计算和分析,总结了拉弯荷载下的设计计算方法。研究表明,内外法兰的抗弯承载力随拉力的增加而减少。与有限元分析相比,半解析计算方法具有足够的计算精度,更高的计算效率。论文所提出的设计计算方法较传统刚性法兰承载力计算理论更为准确和可靠,为内外法兰设计计算提供了依据。     

低温环境下球面法兰的理论设计

采用球面法兰连接,可以对空间连接位置按照设计角度进行角度补偿,由于球面法兰具有角度补偿特点,在对空间管路布局有严格要求的领域将会得到广泛应用.在球面法兰设计中除要参照常规法兰的设计方法外,还要考虑球面法兰本身所具有的特点,包括槽密封结构的确定,球面半径及位置的确定,补偿角度的设计,因角度补偿而带来的螺栓受力分析等.通过理论分析及尺寸协调,给出了以上内容的设计原则和公式.     

梯形槽法兰强度校核程序设计

使用计算机TurboC编译环境编写该梯形槽法兰强度校核程序,用该程序对一组法兰进行强度校核,并对比手工计算结果。程序检验结果表明该程序对梯形槽法兰进行强度校核可靠、准确、便捷,提高了梯形槽法兰设计的工作效率。     

《真空工程设计》简介

<正>由刘玉魁主编,杨建斌、肖祥正为副主编的《真空工程设计》由化学工业出版社将于2016年6月出版。全书共25章,约300万字,涵盖了真空工程设计的各个领域。包括真空概论、真空技术的物理基础、真空获得与测量及气体分析;真空管路设计、真空系统设计、真空与低温容器设计、容器的有限元分析;真空与低温法兰及阀门;真空与低温工程元件、真空与低温工程材料;真空工程中制冷与低温技术、低温测量技术;真空与低温中的热计算基础;真空容器制作时的检漏、焊接、清洗技术;航天器空间环境模拟以及各类真空     

低温真空吸附床矩形法兰设计与强度校核

针对低温、真空的工况特点,本文对吸附床矩形法兰进行了初步设计。分别采用当量圆法和有限元法,对矩形法兰强度进行了校核,并对两种计算方法进行了比较。计算结果表明:采用当量圆法与有限元法相结合的方式,可提高矩形法兰设计的可靠性和精确性,在工程设计中具有重要的指导意义。     

基于四极质谱仪航天器单点检漏应用研究

本文介绍了航天器单点检漏过程中3种常见的单点模型,并依据航天器泄漏设计指标对单点模型的示漏气体浓度进行分析计算。根据现有的四极质谱仪装置GAM500对单点模型进行试验验证,试验说明四极质谱仪可测漏率满足航天器漏率设计指标要求,可以应用在航天器单点检漏工艺中。     

铝合金由对称法兰件热挤压成形极限的理论分析

对铝合金轴对称零件热挤压成形进行了理论分析,总结出零件成形极限的影响因素及规律.通过建立法兰类轴对称零件在热挤压成形过程中变形区应力计算的力学模型,得出应力变化和法兰区外径最大尺寸的表达式.并通过不同应力状态下临界尺寸表达式的对比,分析径向压力P、材料与模具之间的摩擦力τ以及法兰区厚度t对法兰区外径最大尺寸Rmax的影...     

空间材料二次电子发射过程的理论研究

航天器充放电效应故障大多都会引起卫星灾难性事故,对航天器在轨安全运行产生较大的影响。空间材料的二次电子发射系数是决定卫星表面带电速率和充电平衡电位水平的重要材料特征参数,对于卫星表面带电的预测及卫星带电设计选材具有重要的意义。基于蒙特卡洛方法,从理论上分析了材料二次电子的产生、转移及逃逸过程,获得了材料二次电子发射系数的计算方法。实验结果表明该方法能较好地拟合材料二次电子发射系数随入射电子能量的变化趋势,为航天器充放电效应数值模拟和防护设计提供数据支持。     

大偏心率远距离航天器编队飞行设计

为寻求适用于大偏心率远距离航天器编队设计的方法,摒弃了简化航天器相对运动非线性微分方程的传统思路,致力于简化该微分方程的解析解。首先,在同周期假定前提下,由运动学得到了椭圆轨道航天器相对于圆轨道航天器运动的封闭解析解,然后将其展开成傅立叶级数,证明了在特定条件下,单倍频项是最主要的,从而导出了编队飞行设计的新公式。最后以空间圆形编队设计为例,阐明了利用新公式进行编队设计的步骤,并用精确的数值计算验证了设计结果的正确性。与C-W方法和一般轨道参数设计方法相比,推导过程中并未采用小偏心率近距离假定,因此导出的新公式可适用于大偏心率远距离航天器的编队设计。     

航天器热控系统的可靠性设计与分析

针对国内外航天器热控制、热管理技术的发展现状,在详细调研各种航天器热控系统组成原理与功能实现方式的基础上,从可靠性的角度出发,归纳、总结了航天器热控系统中串联、并联、表决、储备四种常见的可靠性设计模式及其相应的可靠性分析计算模型,介绍了其在空间站、月球探测系统、火星探测系统等典型航天器上的应用范例,为进一步的航天器热控系统可靠性设计方法与理论分析奠定了基础。     

Material characterization in flexible flow splitting

There is a significant demand on flexibility in production processes, regarding freedom of part design and freedom of process design. The forming process linear flow splitting satisfies these demands by enriching the semi‐finished product sheet metal with geometric features. Additional flanges and bifurcations in integral style expand the range of component applications. By the further development of flexible flow splitting, these flanges can now be produced along a non‐linear bifurcation line and the application can be expanded on products with varying cross‐section. The continuous steady‐state process linear flow splitting is transferred into a flexible forming process that is characterized by non‐steady states and measurands. Methods of materials characterization are applied to investigate, if those non‐steady properties, that are visible in process characteristics and part geometry, can also be identified in the mechanical behavior.     

Design of elastomer O-ring vacuum seals

Elastomer O-rings were developed in hydraulics, but design criteria from this field are not suitable in high vacuum technique. In the literature, information on O-ring vacuum seals is normally given in the form of tabulated recipes for groove dimensions. Measurements of the mechanical properties (shown in figures) of O-ring enable us to extend these recipes to a general criterion for high vacuum sealing: a contact pressure at the rubber-metal interface of 13 kg/cm². Design of seals using free rings between flat flanges and seals using rings confined in grooves of rectangular and triangular section is treated. Figures and tables of design parameters are given. Correct design in the case of stretched rings is discussed. Important secondary results include the required compression force and the maximum allowed gap (if required) between mating flanges. Figures deal with these parameters. The influence of tolerances is treated too in the given examples.     

波纹腹板H型钢梁受压翼缘局部稳定研究

根据波纹腹板梁翼缘局部失稳的特性提出波纹腹板H型钢梁翼缘局部失稳的理论计算模型,指出波纹腹板梁翼缘失稳相当于两加载边简支,一非加载边弹性转动约束的弹性板。由理论推导得到了翼缘局部弹性屈曲应力计算公式,利用有限元分析验证了该理论模型的有效性。同时探讨了受拉翼缘、梁的长度以及腹板参数变化对受压翼缘局部失稳的影响,最后根据有限元计算结果给出了可供工程设计参考的翼缘宽厚比限值计算公式。     

Design of a new UHV all-metal joint for CLIC

All-metal joints are widely used in the vacuum systems of particle accelerators. The most common ConFlat^® design consists of a flat soft copper gasket captured between two stainless steel flanges with sharp edges (knives). The gasket is plastically deformed and a high contact pressure develops around knives to obtain leak tightness. For large accelerators, a high reliability and a cost-optimized design are required. A smooth internal transition between flanges is needed for the RF waveguides of the compact linear collider (CLIC), with limited deformation of the inner part of the gasket. We present the study of a flange meeting these requirements. First the finite element analysis (FEA) of the Stanford linear accelerator center (SLAC) X-band all-metal joint, which has a similar specification, is shown. Some drawbacks, such as non-homogeneous sealing properties, are highlighted. Then, a new joint design is described. FEA results are presented and are compared with experimental measurements carried out on prototypes.     

Critical Condition Expectancy of Flange Beam at the Loss of Flat Form of Stability with Riveted Flanges under the Influence of Random Forces and Initial Flexures

The functioning of multipart flange beam with riveted flanges, which are loaded with random external forces, is examined. Prior to elastic assembling the beam had random initial flexures of the flanges. We obtained relations for determination of probability of flange beam critical condition by the loss of flat form of flexure under the influence of random shear forces, which occur at the welding points between web plate and flanges of the beam. The examples for determination of probability of critical condition of flange beam under the influence of random initial flexures of the flanges are provided. __________ Translated from Problemy Prochnosti, No. 5, pp. 131 – 137, September – October, 2005.     

LEO大型载人航天器主动电位控制技术进展

LEO大型载人航天器主动电位控制技术可以有效的防护空间等离子体充放电效应对于航天器造成的安全隐患,确保航天员出舱和航天器空间对接作业的顺利完成。通过研究LEO大型载人航天器与空间等离子体的相互作用,从原理上认识空间等离子体对于航天器的危害程度。分析回顾国外主动电位控制技术在LEO大型载人航天器上的成功应用及发展情况,得出启示和初步的主动电位控制系统设计设想。对比国内外主动电位控制领域的核心技术,对主动电位控制技术的发展和应用提出了建议。     

On a compressed elastic–plastic column optimized for post-buckling behaviour

A model of a column is proposed in order to analyse the post-buckling behaviour of a structural element in the elastic–plastic deformation range. The ideal two point I-section applied here simplifies the deformation analysis, that is, the problem of development of plastic zones in a section is eliminated, but still gives the possibility for qualitative analysis and optimization of the post-critical equilibrium paths. The coefficients of linear or parabolic variability of thickness of the flanges and their distance (web width) are accepted as model parameters and hence could be used for design variables in the optimization procedure. Moreover, the stiffness of an additional elastic support of the free end of the beam is also included as a parameter or design variable. A material model is employed with non-linear asymptotic isotropic hardening without the Bauschinger effect. Change of the tangent modulus is continuous and smooth during the transition from the elastic to plastic deformation range. The main goal of the analysis is to determine the values of the design variables for which the post-critical equilibrium paths are stable at least in the specified range of a generalized displacement. The constraints for the constant volume of the flanges and web material are applied. The inequality constraints are imposed on the flange thickness and web width. Various formulations of the optimization problem are proposed for all types of non-linear behaviour, including elastic or plastic buckling and elastic or elastic–plastic post-buckling deformation.     

Time synchronization in orbiting VLBI

Orbiting very long baseline interferometry based on radio transmission of a reference signal from an Earth-bound oscillator is considered. This method provides the possibility of forming a connected-element interferometer between the spacecraft and an Earth radio telescope co-located with the reference oscillator. The reference signal from the spacecraft to the Earth is retransmitted and the round-trip time is continuously measured by assuming reciprocity of the path; the time at the spacecraft is always known relative to a clock on the Earth. The author is concerned with the design of such a round-trip reference system and its accuracy limitations. Spacecraft and Earth station models, continuous contact and simple-frequency timing, ambiguity-free timing link design, and the onboard synthesizers are discussed. A design example is presented