随机振动响应下空间相机支撑结构设计与试验

针对某高分辨率空间相机结构随机振动加速度响应大的问题,对空间相机支撑结构进行了优化设计。(1)建立了基于随机振动响应分析的数学模型,推导了随机振动均方根响应表达式;(2)基于三点定位原理和双脚架柔性结构原理设计了相机支撑结构,以相机安装点RMS值最小为目标,基频作为约束,建立了相机支撑结构随机响应优化模型,对支撑结构柔性环节位置进行了尺寸优化设计,采用MSC.PatranNastran有限元分析软件对优化处理后的支撑结构进行了工程分析,相机安装点随机响应RMS值最大19.6 grms;(3)对相机支撑结构进行了随机振动试试验。结果显示:有限元分析结果与试验测量数据符合的较好,最大相对误差为8.2%,所设计的空间相机支撑结构满足空间相机使用要求,验证了所采用优化方法的可行性。     

随机振动响应下空间相机支撑结构设计与试验

针对某高分辨率空间相机结构随机振动加速度响应大的问题,对空间相机支撑结构进行了优化设计。建立了基于随机振动响应分析的数学模型,推导了随机振动均方根响应表达式。基于三点定位原理和双脚架柔性结构原理设计了相机支撑结构,以相机安装点RMS值最小为目标,基频作为约束,建立了相机支撑结构随机响应优化模型,对支撑结构柔性环节位置进行了尺寸优化设计。采用MSC.PatranNastran有限元分析软件对优化处理后的支撑结构进行了工程分析,相机安装点随机响应RMS值最大19.6 grms。最后,对相机支撑结构进行了随机振动试验,结果显示,有限元分析结果与试验测量数据符合的较好,最大相对误差为8.2%,所设计的空间相机支撑结构满足空间相机使用要求,验证了所采用优化方法的可行性。     

轻型钢框架支撑体系振动特性与抗震性能分析

为了分析不同支撑形式对钢框架结构体系振动特性的影响,利用PKPM软件设计了X型、V型和人字型3种不同支撑形式的12层钢框架支撑结构,提供了主要构件的尺寸和结构的振动特性,再利用有限元软件ANSYS和SAP2000对3种不同支撑的自振特性分别进行了分析,探明了不同支撑形式对该结构体系的动力特性的影响;利用ANSYS软件进...     

三套管自复位屈曲约束支撑滞回性能研究

在结构中合理安装自复位屈曲约束支撑可以有效地减少结构损伤和结构残余变形。该文提出了一种新型三套管自复位屈曲约束支撑,对其滞回性能进行实验研究。通过拟静力试验考察了初始预应力,芯材管有效横截面积对支撑耗能能力以及控制残余变形效果的影响。采用有限元方法对支撑的滞回性能进行了参数分析,并通过理论推导给出了支撑的刚度和承载力计算公式。研究结果表明合理设计的三套管自复位屈曲约束支撑具有良好的耗能能力和自复位性能,有限元分析结果与试验结果吻合较好,理论推导得到的刚度和承载力计算公式能准确给出支撑滞回曲线上的特征点。     

低温贮箱新型绝热支撑结构随机振动模拟分析

航天器在火箭发射过程中会经历严酷的随机振动环境,支撑结构作为航天器的关键承载部件,其强度和刚度能否满足要求显得十分重要。运用有限元分析软件ansys对低温贮箱的绝热支撑结构进行了随机振动的模拟分析,得出了支撑结构在随机激励载荷作用下的响应,响应结果表明,支撑结构的强度和刚度满足使用要求。。     

不同支撑和转子装配方式的高速电机临界转速分析

用有限元方法研究了滚动轴承支撑的整体式转子和电磁轴承支撑的焊接式转子这两种高速电机轴承-转子系统的临界转速。在分析两种系统的支撑刚度特性及转子结构装配关系的基础上建立了有限元模型,计算出系统的临界转速并对不同支撑和装配方式对轴承-转子系统临界转速的影响进行了讨论,最后通过锤击实验和整机实验全面验证结果的有效性,为高速电机轴系设计和动力学分析提供了参考。*     

装有腹板式钢制防屈曲支撑框架结构振动台试验及分析

为研究腹板式钢制防屈曲支撑及普通支撑在动力荷载下力学性能,对装有腹板式钢制防屈曲支撑及普通支撑框架结构进行模拟地震振动台试验,比较两种支撑的减震效果。采用有限元方法进行振动台试验数值计算。试验及有限元分析结果均表明,腹板式钢制防屈曲支撑对结构位移反应有较好控制效果,为理想的消能装置。小震时两种框架结构层间位移基本相同,亦可为结构提供初始刚度;随地震峰值的增加框架结构层间位移远小于普通支撑框架结构,腹板式钢制防屈曲支撑可在主体结构进入弹塑性变形前消耗地震能量,降低结构损伤。     

无人机机载低温液氢储罐结构设计与强度分析

完成机载低温液氢储罐的基本结构设计,通过设计使用新型绝热支撑结构,解决了传统支撑结构热流量过大的问题,通过薄膜容器理论和有限元数值模拟方法对储罐进行强度计算与校核,使用赫兹接触理论与ANYSY数值模拟两种方法对绝热支撑进行结构分析并通过拉伸实验校核强度。为壳体接管接柱结构和点接触式支撑及类似轴承结构提供了一套简单有效的分析方法。研究结果表明:点接触式支撑结构最大应力比传统支撑结构大9倍,支撑结构和储罐可以满足强度要求。     

大口径反射镜侧支撑结构力学分析

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.     

一种新型车用低温气瓶后端支撑结构性能分析

提出了一种新型的低温气瓶后端支撑结构,使用有限元数值仿真方法对该结构进行传热分析和承载能力分析。仿真结果表明,与常用的十字形支撑结构相比,该结构具有更低的漏热率并且具有良好的承载能力。该结构能够提高车载低温气瓶的绝热性能、满足承载能力要求。     

Experimental study on polarization lens formed by asymmetrical metallic hole array

A polarization bifocal lens based on the polarization effect caused by asymmetrical hole arrays had been designed, fabricated, and characterized experimentally. By considering the fact that the skin depth of an infrared electromagnetic field inside metal is much shorter than the incident wavelength, a polarization bifocal lens composed of high deep-width ratio metallic holes was realized by using a gold-coated silicon structure to replace the one directly formed on a thick metal film. An infrared optical experiment setup is built based on the secondary imagery method for characterizing the focal length of the designed bifocal lens. The measured focal lengths of the fabricated bifocal lens coincide well with the designed values, which proves the validity for realizing the polarization elements with the proposed structure and the feasibility of the fabrication process.     

透镜阵列光刻法消差原理分析

透镜阵列光刻法用一个柱面阵列透镜代替常规光刻法中的柱面透镜形成光程差,将由衍射所引起的瞬变图形错开,消除由于光刻模板与被刻光栅之间因间隙引起的衍射误差。用光学传递函数方法说明了透镜阵列消除光刻中衍射误差的原理。实验表明透镜阵列光刻法,可以较好的消除衍射误差,研制出高质量的光栅。     

Uniform irradiation of adjustable target spots in high-power laser driver

For smoothing and shaping the on-target laser patterns flexibly in high-power laser drivers, a scheme has been developed that includes a zoom lens array and two-dimensional smoothing by spectral dispersion (SSD). The size of the target pattern can be controlled handily by adjusting the focal length of the zoom lens array, while the profile of the pattern can be shaped by fine tuning the distance between the target and the focal plane of the principal focusing lens. High-frequency stripes inside the pattern caused by beamlet interference are wiped off by spectral dispersion. Detailed simulations indicate that SSD works somewhat differently for spots of different sizes. For small spots, SSD mainly smooths the intensity modulation of low-to-middle spatial frequency, while for large spots, SSD sweeps the fine speckle structure to reduce nonuniformity of middle-to-high frequency. Spatial spectra of the target patterns are given and their uniformity is evaluated.     

Design and implementation of optical system for Placido-disc topography

Corneal topography provides powerful support in the diagnosis and treatment of corneal disease by displaying the corneal surface topography in data or image format. To realize the precise detection of corneal surface topography, an optical system for the corneal topography that is based on a Placido disc is designed, which includes a ring distribution on a Placido disc, an imaging system and a collimating illumination system. First, a mathematical model that is based on the corneal topography working principles is established with MATLAB to determine the distribution of white-and-black rings on the Placido disc, in which the ellipsoid facial rings-target of the Placido disc is utilized. Second, the imaging lens structure is designed and optimized by Zemax software. Last, the collimating illumination lens structure is designed by paraxial ray trace equations. The quality of the corneal topography, which is based on our designed optical system, is evaluated. The high-contrast image of uniformly distributed white-and-black rings is observed through the CCD camera. Our optical system for the corneal topography has high precision, with a measuring region of the cornea with a diameter of approximately 10 mm. Therefore, the creation of this optical system offers guidance for designing and improving the optical system of Placido-disc topography.     

Planar-structure microscope-lens for simultaneous acoustic and optical imaging

A new type of combined acoustic and optical microscope lens with a planar structure is proposed. It can meet the demand for simultaneously obtaining both an acoustic image and its optical counterpart. The lens is composed by uniting a Fresnel-zone-type acoustic lens developed by the authors with a rod-type gradient-index optical lens (SELFOC). An acoustic beam is converged to a focal point in water by an acoustic planar lens that is composed of annular grooves formed on the end of the SELFOC rod. An optical beam, emitted by a He-Ne laser source and guided into the rod, converges due to the gradient of the refractive index and focuses on a spot in water. By designing the length of the rod properly, the focal spot of the optical beam is set to coincide with that of an acoustic beam. The design and fabrication of the lens are described, and results of some preliminary experiments for simultaneous observation of acoustic and optical images of the same portion of a specimen are shown.     

透镜主动光学的像差补偿性能

针对透射式投影物镜中由于不均匀照明产生的像散,提出了采用平面透镜作为主动光学元件以补偿像散的方法。本文对直径为Φ140mm,通光孔径为Φ120mm的平面透镜的支撑结构进行设计和有限元分析,分析了支撑结构的各个关键参数、镜片厚度和驱动力大小对面形的影响,得到了支撑结构的关键参数和驱动力对面形的影响规律为线性曲线,镜片厚度对面形的影响规律为指数下降曲线和不同驱动力导致的面形图。结果表明,本支撑结构在补偿像散时,面形补偿分辨率约为2nm,引入的高阶像差可以忽略,设计分析结果为投影物镜中主动光学镜片的选择和支撑结构的设计及实验提供依据。     

Raman imaging of carious lesions using a hollow optical fiber probe

Raman spectroscopy using a hollow optical fiber probe with a glass ball lens at the distal end is proposed for detection of early caries lesions. Raman spectroscopy on carious lesions of extracted teeth showed that the probe enables measurement with a high signal-to-noise ratio when combined with a ball lens with a high refractive index. The proposed probe and lens combination detects changes in Raman spectra caused by morphological differences between sound and carious enamel. We also obtained a high-contrast image of an early carious lesion by scanning the tooth surface with the probe.     

Ab initio synthesis of linearly compensated zoom lenses by evolutionary programming

An approach for ab initio synthesis of the thin lens structure of linearly compensated zoom lenses is reported. This method uses evolutionary programming that explores the available configuration space formed by powers of the individual components, the intercomponent separations, and the relative movement parameters of the moving components. Useful thin lens structures of optically and linearly compensated zoom lens systems are obtained by suitable formulation of the merit function of optimization. This paper reports our investigations on three-component zoom lens structures. Illustrative numerical results are presented.     

弹性支撑模型对火箭发射过程结构振动响应影响研究EI北大核心CSCD

固体火箭从发射筒发射过程中,采用弹性支撑降低火箭结构与发射筒内壁接触引起的冲击,弹性支撑力学模型对火箭发射过程中结构振动响应计算存在影响。利用多体动力学建立包含火箭、发射筒、弹性支撑在内的发射动力学模型,在火箭发射物理过程分析基础上,利用ANSYS/LS-DYNA软件建立火箭壳体与弹性支撑局部有限元模型,获得了火箭壳体与弹性支撑接触面积变化对支撑刚度影响规律,在此基础上,提出了用于火箭发射多体动力学建模的弹性支撑改进模型,求解弹性支撑模型改进前后火箭发射过程结构振动响应与弹性支撑支反力,分析了弹性支撑模型改进对结构振动响应的影响及其原因。结果表明:提出的弹性支撑改进模型可以准确描述火箭尾部结构脱离弹性支撑过程中接触面积逐渐变化到零的物理过程;与弹性支撑模型改进前相比,改进后结构弯矩响应峰值显著减小。该成果有助于准确评估火箭发射过程结构响应水平,对于火箭结构精细化设计具有工程意义。     

层状火焰中透镜效应的研究

分析预混气体燃烧气流形成的层状结构，建立其分界面的模拟方程；用矩阵方法教育处光透射率和厚度灵敏因子，得到层状火焰透镜的性能参数；引进光学材料的规化热差系数和色差系数，建立无热差光学系统的方程，并提出了消除温度对其焦距影响的方案，结果表明：精细的火焰多层膜层结构的透镜效应研究对获得极准确的激光全息信息非常有益。