具有力感知功能的四臂式MEMS微夹持器研制

为了解决夹持器小型集成化、夹持力可控的问题，本文采用体硅加工技术成功的研制了一种基于单晶硅的、具有微力检测功能的新型四臂式MEMS微夹持器。以压阻检测技术为基础，利用MEMS侧面压阻刻蚀工艺将力传感器集成在微夹持器的夹持臂末端，实现夹持力的微力检测。采用有限元软件对微夹持器机构和传感器弹性体进行分析。S型柔性梁结构的设计将梳齿驱动的直线运动转化为夹持臂末段的转动，结合四臂式的末段结构，有效的扩展了夹持器的夹持范围。利用硅玻璃键合技术实现夹持臂的电隔离，通过施加80V电压，夹持臂的单臂运动范围为25靘，夹持器的夹持范围30-130靘。实验标定出传感器的最大量程在1mN以上，分辨率为3霳，可以实现夹持力的有效反馈。     

Six degrees of freedom vibration transmissibility measurement of flexural opto-mechanical structures with 3-axis acceleration sensors

At an early stage of a high-resolution flexural opto-mechanical system design, it is essential to analyze its dynamic characteristics for assessing image quality due to environmental vibration, an experimental method to measure six degrees of freedom (6-DoFs) vibration transmissibility of flexural opto-mechanical structures is proposed in this article. A typical flexural opto-mechanical structure consists of an optical component, a mechanical component and several flexural modules. Using the developed method, optical and mechanical components are considered as rigid bodies. Two feature points which are uncoupled in motion are set in the components separately, and they can express 6-DoFs vibration of each component moderately. Several key points are set in each component too, and their vibrational accelerations are measured with 3-axis acceleration sensors firstly. Then, motion relations between the feature points and key points are established, 6-DoFs vibrational acceleration spectrums of the two feature points are analyzed, and 6-DoFs vibration transmissibility between them is calculated. Thirdly, the experiment is carried out for twenty times, and average 6-DoFs vibration transmissibility is calculated. Uncertainties of this method are discussed with numerical analysis and experiments.     

Key techniques and applications of adaptive growth method for stiffener layout design of plates and shells

The application of the adaptive growth method is limited because several key techniques during the design process need manual intervention of designers. Key techniques of the method including the ground structure construction and seed selection are studied, so as to make it possible to improve the effectiveness and applicability of the adaptive growth method in stiffener layout design optimization of plates and shells. Three schemes of ground structures, which are comprised by different shell elements and beam elements, are proposed. It is found that the main stiffener layouts resulted from different ground structures are almost the same, but the ground structure comprised by 8-nodes shell elements and both 3-nodes and 2-nodes beam elements can result in clearest stiffener layout, and has good adaptability and low computational cost. An automatic seed selection approach is proposed, which is based on such selection rules that the seeds should be positioned on where the structural strain energy is great for the minimum compliance problem, and satisfy the dispersancy requirement. The adaptive growth method with the suggested key techniques is integrated into an ANSYS-based program, which provides a design tool for the stiffener layout design optimization of plates and shells. Typical design examples, including plate and shell structures to achieve minimum compliance and maximum bulking stability are illustrated. In addition, as a practical mechanical structural design example, the stiffener layout of an inlet structure for a large-scale electrostatic precipitator is also demonstrated. The design results show that the adaptive growth method integrated with the suggested key techniques can effectively and flexibly deal with stiffener layout design problem for plates and shells with complex geometrical shape and loading conditions to achieve various design objectives, thus it provides a new solution method for engineering structural topology design optimization.     

大型空间离轴三反相机分体支撑结构设计

针对某1 m分辨率、200 km幅宽的大尺度空间相机框架支撑结构轻质量、高刚度的设计要求,设计了一种轻型分体支撑结构。首先从大型空间离轴三反相机研制需求出发,综合比刚度、热稳定性及加工工艺等因素选择了性能良好的高体份SiCp/Al复合材料;然后以结构质量分数为约束条件,建立以基频为目标函数的拓扑优化数学模型,得到了拓扑结果清晰的各分体结构最优传力路径;进一步对主支撑结构各部分尺寸进行二次优化,得到了各分体结构的最佳构型和最优设计尺寸。设计后的分体支撑结构总重为227.8 kg,轻量化率达到93.9%,满足了高轻量化和高刚度要求。有限元分析结果及力学样机试验结果表明:分体支撑结构满足遥感相机整机基频大于50 Hz的刚度要求,在升温5℃工况下反射镜变形在公差范围之内,完全符合卫星平台对光学载荷的要求;力学样机在振动实验前后反射镜组件相对偏移角度均不超过22″,具有较好的稳定性,证明了拓扑优化和尺寸优化方法的合理性和可行性。本文提出的分体支撑结构设计对大型空间离轴相机支撑设计具有较高的工程实践价值。     

Analytic solutions for vibration characteristics of a multi-beam structure

The first purpose of this paper is to mathematically analyze the vibration characteristics of four parallel and uniform beams that are joined by a tip body at their free ends. This beam structure is often found in many mechanical structures such as robots, space constructions, and optical pickup actuators in optical disc drives (ODDs). To analyze the vibration characteristics of this beam structure, this paper considers the motions in all six directions that are coupled to each other. Mathematical expansion using the energy conservation law applied to this beam structure yields four characteristic equations, which are related to a pure-axial (PA) vibration, a coupled bending-torsional (CBT) vibration, and two coupled axial-bending (CAB) vibrations. In addition, the correctness of the equations is verified by showing that the natural frequencies from these equations match those from a finite element (FE) analysis.The second purpose of this paper is to contribute to the performance improvement of an optical pickup actuator for ODDs by analyzing key parameters of the characteristic equations. This is one of the few papers that analytically derives solutions for the natural frequencies and modes of optical pickup actuators in all six directions. From the perspective of practical usefulness for the design of optical pickup actuators, this paper describes how to reduce rotation in the two CAB beam vibrations by investigating the relationship between design parameters and rotating properties.     

Vibration of two cantilever beams clamped at one end and connected by a rigid body at the other

This study presents the pure bending and coupled bending-torsional vibration characteristics of a beam structure which consists of two cantilever beams and a rigid body at their free ends. This structure is available in many mechanical structures such as robots, space constructions, and optical pickup actuators in optical disc drives (ODDs). In order to depict the vibration of the beam structure originating from the deflection and torsion of two beams, the motion equations and continuity conditions are analytically induced by using energy conservation. In the process that the free vibration problem is solved, two independent characteristic equations are obtained. The former is an equation for the pure bending vibration of two beams, and the latter is for their coupled bending-torsional vibration. It is proved that these characteristic equations are exact by comparing natural frequencies obtained from FEM. As natural frequencies are described in many dimensional variations, the relation between vibration characteristics and the dimensions of the given system is also investigated. Finally, resonant frequencies from test results are presented to confirm the validation of this study for a new type optical pickup actuator. This paper was recommended for publication in revised form by Associate Editor Eung-Soo Shin Kyung Taek Lee received a Ph.D. degree in Mechanical Engineering from Yonsei University, Seoul, Korea in 2003. He joined LG Electronics, Seoul, Korea, in 1989, where he has worked on precise mechanical structures and microactuating systems for optical information storage devices, as a Research Engineer. His current interests include microactuators for position control, haptic elements for mobile devices, and etc.     

An innovative method to build support structures with a pulsed laser in the selective laser melting process

In selective laser melting machines, continuous laser are usually used to melt the powder. The support structures, which are inevitable when dealing with elaborated pieces, necessitate a complex design by CAD in order to be easily removed. This paper propose an innovative laser manufacturing method by combining pulsed and continuous modes of radiation. Continuous radiations are used for the object-to-build itself, in order to guarantee the requested mechanical properties. Pulsed radiations are used to build the support structures. The resulting support structures have sufficient mechanical properties to withstand the deposition system and to evacuate heat, and are easy to remove from the denser parts. This building method reduces drastically time to market since the same laser can be used in two modes and because pulsed radiation allows very high scanning speed with high power during the building of support structures.     

大型带钢轧机动态特性分析与动力学修改

为避免轧机运行中出现不稳定振动,提出轧机故障诊断与设计缺陷分析的综合方法。首先,在现场运行状态下采集控制系统参数与轧机结构振动等数据;然后,采用支持向量回归技术进行控制系统辨识,根据得到的辨识模型诊断控制系统的稳定性,提出了环节动力学分析的概念与方法,建立控制系统与机械结构的混合数学模型,实现不同损伤状态下的仿真与运行稳定性预测;最后,通过结构动力学修改或再设计,消除由于结构损伤或设计不当导致的轧机自激振动。     

神光-Ⅲ主机近背向散射诊断光学系统设计

通过分析激光聚变中近背向散射光的收集方式,提出了采用金属环形椭球镜有效收集神光-Ⅲ主机装置的近背向散射光并测量其能量份额的方法。给出了椭球镜参数的设计方法。大口径椭球镜采用4块拼接形式,便于进入入口为φ1.0 m的靶室;镜体采用超硬铝材、三角形减重槽设计,实现了高稳定性、轻量化。介绍了光学系统总体结构,并对其集光效果进行了模拟评价。分析了镜体设计中的关键问题,并提出采用点激光器阵列进行中间过程面形监测的方法,避免了工序反复。分析了系统杂散光来源,采取了物理隔离、光学吸收和滤光片过滤等措施降低杂散光干扰。研制的环形椭球镜外径为1 200 mm,内径为400 mm,最大离轴量为1 411 mm,最大厚度为67 mm,重量约为48 kg;对5 mm的物方视场,像点光斑大小约为φ1.2 mm。实验显示该近背向散射诊断系统可满足神光-Ⅲ主机背向散射诊断的需求。     

空间成像光谱仪主体支撑技术研究

为了改善某型号空间成像光谱仪主体支撑方式对系统光机结构稳定性的影响,从三个方面分析了系统光机结构稳定性的表达方式,介绍了常用空间光学遥感仪器的支撑方式。在传统支耳支撑方式不能满足离轴非球面三反射镜（TMA）系统热稳定性的情况下,提出了一种新的双耦合的支撑方案并对其进行了理论分析。优化设计过程中,采用有限元分析软件MSC.PATRAN对的三维样机进行工程分析,结果表明,在正弦振动载荷作用下,主体一阶频率为95Hz;在10℃均匀温降与自重耦合作用下,各反射镜面RMS最大值为12nm、PV最大值为60nm,主镜绕Z轴的转角由原来的55'降低为12'。热真空环境下整机成像试验获得的光谱数据验证工程分析的正确性,双耦合的支撑方案能满足整机刚度和光机系统的热稳定性的要求。     

新型轻质大口径空间反射镜支撑设计

摘要：随着空间反射镜口径的增大,光学系统总质量随之剧增,这与当前光学遥感器轻小型化的发展趋势相矛盾。为了更好的满足空间光学遥感器发展的需要,文章从主反射镜组件的轻质化设计入手,从结构材料热匹配的设计、主镜轻量化形式的确定以及支撑结构的合理设计三个角度系统地进行了一体化结构—热设计。针对某型卡塞格林系统Φ630mm口径主镜进行了轻质化设计,三点为主多点为辅的支撑方案在保持组件结构刚度满足力学要求的同时,使反射镜具有良好的热尺寸稳定性。在综合考虑加工和工作状态后,最终确定了一种满足设计要求的整体优选方案,经最终分析计算确认,主镜组件镜面综合面形误差PV值均小于λ/10,各项指标完全满足光学系统对主反射镜的设计要求。