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在同轴望远镜系统中,主镜和次镜的相对位置和姿态有非常严格的要求,需要将次镜设计成多自由度可以调整的机构.针对次镜调整机构的性能要求,提出一套由二维XY移动平台和三维Tip/Tilt/Focus平台组合成的五自由度次镜调整机构方案.其中三维Tip/Tilt/Focus平台由3个驱动器、定平台与动平台组成,驱动器与动平台之间由柔性铰链连接,通过3个驱动器的伸缩和柔性铰链的转动来实现动平台的三自由度运动.对三维Tip/Tilt/Focus平台的运动学原理作了详细介绍,深入地讨论柔性铰链弯曲刚度和轴向刚度与几何参数的关系.研究结果为五维调整机构及柔性铰链的设计提供客观依据,具有较大的实际意义. 相似文献
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大口径望远镜主镜支撑优化分析 总被引:4,自引:1,他引:3
大口径望远镜主镜的面形精度是影响望远镜成像质量的关键因素之一.光电系统中主镜轴向支撑点位置,对面形精度起着非常重要的作用,主镜支撑点位置合理与否,在一定程度上影响着光学系统的成像质量.本文对大口径望远镜主镜的轴向支撑和径向支撑技术进行了详细地研究,利用有限元软件ANSYS建立了主镜的参数化模型,对不同口径主镜的轴向支撑点数目和位置进行了优化,从而给出了最佳支撑点的位置.优化分析结果表明了,主镜的面形精度满足系统的精度要求,并且轴向支撑对镜面的面形影响较大. 相似文献
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大口径主反射镜支撑结构设计 总被引:2,自引:2,他引:0
大口径空间反射镜支撑技术是空间相机研制中的关键技术之一.从保证反射镜组件刚度、强度和热尺寸稳定性的角度出发,对某型卡塞格林系统中980 mm口径主反射镜支撑结构进行了设计.提出采用背部六点支撑,三点为主另外三点为辅的支撑方案,通过在支撑结构中设置柔性环节,从而解决了大口径主反射镜在自重作用下面形精度满足要求而在温变栽荷作用下面形精度严重超差的问题.利用有限元分析软件进行了主镜组件的静、动态刚度及热尺寸稳定性分析,并在分析的基础上对支撑结构中的柔性环节结构参数进行修正,在保证支撑刚度的同时降低了重力、装配应力和热应力对面形精度的影响.分析和试验结果表明,主镜在重力和4℃均匀温升载荷下面形精度达到PV<λ/10,RMS相似文献
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将超高层建筑束筒结构与其基础等效连续化为一个支撑在半无限大弹性地基上具有三维连续分布刚度和质量特性的加劲薄壁筒组合体,并以此模型,对其在多维简谐动力作用下的稳态反应进行了半解析分析,并计算出了共振响应,那就是当激励荷载的频率与结构系统的自振频率很接近时,结构的动力响应会出现非常大的突变。计算结果表明:模型的简化是合理的、可行的,从而为超高层建筑束筒结构的整体动力分析提供了一种可行的方法,并给出了几点对此类结构的抗震设计有指导意义的结论。 相似文献
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从理论上论述了在真空望远镜主反射镜的几种侧支撑结构,并运用有限元法对之分别进行了分析计算,得到使用了不同侧支撑结构的真空望远镜主镜在不同观测角度时的表面变形结果,通过比较变形结果,得到使用新配方粘接剂的粘接侧支撑机构支撑效果更好.在已确定使用Grubb十八点底支撑结构后,分析了使用粘接剂的侧支撑结构主反射镜变形与应力情况.通过有限元分析结果,得出变形结果符合整个光学系统的公差要求,同时证明了使用改性粘接剂的侧支撑系统可有效减少光学件表面变形量. 相似文献
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建立某12V型柴油机的有限元模型,进行整机振动频响计算,并结合AML方法建立该柴油机的声辐射预测模型。在此基础上,开展主承力结构不同设计参数方案下的内燃机整机振声响应计算,从而确定影响内燃机振声响应的主承力结构关键设计要素:主轴承座-盖宽度、机体箱体内侧板位置及机体箱体外侧板厚度,并对上述设计参数进行关于内燃机整机声功率级的响应面分析。通过响应面分析的结果,获得了该柴油机主承力结构的最优设计方案,对比优化前后整机声功率级值,主承力结构优化后整机声功率级值减小了1.87 d B(A),即优化后声功率比原始结构下声功率减小了1/3,优化效果显著。 相似文献
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The structural intensities in isotropic and orthotropic laminae and composite laminated plates with and without a hole of different rim conditions are studied using the finite element method. Patterns of superposition among structural stress fields, intensity vectors, mode shapes and streamlines of energy flow are obtained for the various cases. It is found that the hole completely changes the distributions of the stress and energy flow path in plates. Despite its nature of mode dependent the pattern of energy flow may be different from each other despite having similar structural mode shapes, moreover the position of maximum stress is not corresponding to the position of maximum structural intensity. 相似文献
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The spontaneous emission from a driven four-level tripod atom embedded in an anisotropic photonic crystal is investigated in this paper. We find that time-evolution properties and components of the emitted fields are dependent on the relative position of the upper level of the atom from the band edge and the space between two lower levels. The radiation field emitted by the atom is calculated more accurately. The energy is translated from one form to another with the increase of distance from the atom and the upper level's relative position. The evolution properties and the spontaneous spectrum are also studied. The results analyzed here are consistent with the distribution of emitted fields. 相似文献
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Dell'Acqua-Bellavitis LM Ballard JD Vajtai R Ajayan PM Siegel RW 《Journal of nanoscience and nanotechnology》2007,7(7):2335-2342
Arrays of catalytically-grown multi-wall carbon nanotubes were grown using identical conditions in a chemical vapor deposition environment, but cooled at different cooling rates, to identify the influence of cooling rate on the structural properties of the nanotube at the catalyst-wall interface. Ex-situ transmission electron microscopy led to the identification of twist, twin, and tilt domain boundaries in all samples irrespective of cooling rate. In addition, the relative position of twist, twin, and tilt domain boundaries in nanotubes cooled at different rates was maintained uniformly across all samples cooled at different rates. The results are interpreted in light of the concurrence of base- and tip-growth for the catalytic synthesis of nanotubes, suggesting a rather steady position occupied by the domain boundaries coupled to the catalytic particles. 相似文献
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为了简化平衡头的自锁结构,提出了一种磁路自锁型电磁—永磁混合式平衡头。当线圈不通电时,依靠相邻两个永磁体与磁性内齿盘之间的磁阻最小,平衡头锁定在稳定位置。当线圈通电后,在电磁场和永磁体作用下,平衡头启动并向下一稳定位置运动。讨论了影响平衡头自锁力矩和启动力矩的结构参数,并对各个参数的取值范围进行了初步设计。通过有限元电磁分析,得到了其与自锁力矩、启动力矩之间的量化关系。基于此,设计并开发了一套电磁平衡头样机,完成了其自锁可靠性计算和启动能力试验。对比计算和试验结果,平衡头结构设计和参数选取正确。研究工作为该平衡头的工程应用提供了重要的参考价值。 相似文献
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竖向地震作用下充满液体管道的地震反应分析 总被引:7,自引:0,他引:7
用半解析法求解竖向地震作用下充满液体管道的弯曲振动反应。针对某些介质和结构参数,给出了一些数值结果,得出了管道内部液体压力对管道动力响应的影响及相对地震反应对其动力响应影响的若干初步结论。对地上充满液体管道的地震效应作了一些理论上的探讨。 相似文献
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Rikard B. Heslehurst 《Composite Structures》1996,35(4):369-374
Most composite structures are orthotropic with respect to the major structural loading direction, i.e. the 0 ° fibres are along the principal bending axes of an aircraft wing (the spar line). The laminate stiffness properties are given with the laminate orthotropic axes aligned with the structural axes. If the orthotropic axes are not aligned to the structural axes, then the laminate stiffness properties are generated from classical laminated plate theory with individual ply angles rotated through the appropriae angle of transformation. In this discussion, the transformation of a laminate's stiffness from the on-axis position to an off-axis position is accomplished in one step. Two typical examples are shown to illustrate where and why such a transformation is used. 相似文献
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E. L. Aero 《Journal of Engineering Mathematics》2006,55(1-4):81-95
A new model of a double continuum with variable local topology is used to develop an essentially nonlinear theory of a medium
with a cardinally rearranged periodic structure. This theory is based on a continualization of the periodic structure of a
complex crystalline lattice consisting of two sublattices. In the long-wave approximation, the standard linear theory of acoustic
and optic oscillations of the complex lattice is generalized. In this generalization, an internal translational symmetry of
relative shear of the sublattices is taken into account. As a result, the interaction between the sublattices is expressed
in terms of a nonlinear periodic force described, in particular, as a sine of the relative shear of two atoms belonging to
an elementary cell. The corresponding equations describe elastic and inelastic catastrophic deformations due to the structural
instability which accompanies phase transitions, twinning, defect formation, etc. Some static and dynamic problems are analyzed 相似文献
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《Nanotechnology, IEEE Transactions on》2008,7(5):586-595