复合材料构件热压罐成型模具温度均匀性分析

热压罐固化中成型模具的温度分布对复合材料固化质量有显著影响,提高与构件直接接触的模具型面温度均匀性有利于改善内部温度梯度,减小固化变形,提高成型精度。本文以复合材料构件热压罐框架式成型模具为对象,应用有限元方法,分析模具温度的分布,研究模具支撑结构对型板表面温度均匀性的影响。研究表明,支撑板厚度越薄,温度均匀性越好,与进气风口平行方向的支撑板对温度均匀性的影响更为显著,因此可优先考虑增加与进气风口垂直方向支撑板厚度来增加模具刚度。在保持面积不变的前提下,改变散热孔的形状,发现菱形与圆形散热孔具有较强的抗变形能力,而方形散热孔使得型板表面温度分布更加均匀。通过控制散热孔的布局改变风道时,发现T型风道对于改善温度均匀性的效果最佳。     

二维复值Ginzburg-Landau方程的一个高阶紧致ADI差分格式

对二维复值金兹堡朗道(Ginzburg-Landau,GL)方程提出一个基于时间分裂的高阶紧致交替方向隐式有限差分格式。本文通过时间分裂法将GL方程分裂成一个非线性子问题及两个线性子问题,对非线性子问题以及其中一个线性子问题均通过精确积分进行计算,并对另一线性子问题构造紧致交替方向隐式差分格式进行数值计算。实际计算中,在每一时间步,利用追赶法求解一族常系数三对角线性代数方程组,从而使得算法既具有较高精度又拥有较快的计算速度。数值实验表明该算法在时间和空间方向分别具有二阶和四阶精度,并模拟了方程的一些动力学行为。     

基于ICKF的永磁同步电机无传感器控制方法

针对在永磁同步电机(Permanent magnet synchronous motor,PMSM)中安装传感器带来的高成本、体积增大、可靠性降低和易受环境干扰等问题,提出采用迭代容积卡尔曼滤波(Iterative cubature Kalman filter,ICKF)算法来估计电机转速和转子位置,并将其应用于永磁同步电机无传感器控制。首先,建立了PMSM在α-β坐标系下的离散数学模型。其次,在Matlab/Simulink环境下分别建立了基于容积卡尔曼滤波(Cubature Kalman filter,CKF)和ICKF的PMSM转速、电流双闭环的无传感器矢量控制系统仿真模型,并进行了给定转速和加负载两种工况的仿真验证。最后,基于TMS320F28335芯片搭建了硬件实验验证平台。仿真分析与实验结果均表明,迭代容积卡尔曼滤波算法应用于永磁同步电机无传感器控制中抗负载变化干扰性好、电机运行稳定、电机转速和转子位置估计精度高,可满足对电机精确控制要求较高的应用场合,具有重要参考价值和推广意义。     

Torque Distribution of Electric Vehicle with Four In-Wheel Motors Based on Road Adhesion Margin

With the worsening of energy crisis and environmental pollution,electric vehicles with four in?wheel motors have been paid more and more attention. The main research subject is how to reasonably distribute the driving torque of each wheel. Considering the longitudinal motion,lateral motion,yaw movement and rotation of the four wheels,the tire model and the seven DOF dynamic model of the vehicle are established in this paper. Then,the torque distribution method is proposed based on road adhesion margin,which can be divided into anti ? slip control layer and torque distribution layer. The anti?slip control layer is built based on sliding mode variable structure control,whose main function is to avoid the excessive slip of wheels caused by road conditions. The torque distribution layer is responsible for selecting the torque distribution method based on road adhesion margin. The simulation results show that the proposed torque distribution method can ensure the vehicle quickly adapt to current road adhesion conditions,and improve the handling stability and dynamic performance of the vehicle in the driving process.     

Rotation Control of a 3-DOF Parallel Mechanism Driven by Pneumatic Muscle Actuators

The pneumatic muscle actuator(PMA) has many advantages,such as good flexibility,high power/weight ratio,but its nonlinearity makes it difficult to build a static mathematical model with high precision. A new method is proposed to establish the model of PMA. The concept of hybrid elastic modulus which is related to the static characteristic of PMA is put forward,and the energy conservation law is used to achieve the expression of the hybrid elastic modulus,which can be fitted out based on experimental data,and the model of PMA can be derived from this expression. At the same time,a 3-DOF parallel mechanism(a new bionic shoulder joint)driven by five PMAs is designed. This bionic shoulder joint adopts the structure of two antagonistic PMAs actualizing a rotation control and three PMAs controlling another two rotations to get better rotation characteristics. The kinematic and dynamic characteristics of the mechanism are analyzed and a new static model of PMA is used to control it.Experimental results demonstrate the effectiveness of this new static model.     

Active Design Method of Tooth Profiles for Cycloid Drive Based on Meshing Efficiency

An active design method of tooth profiles for cycloid gears based on their meshing efficiency is proposed.This method takes the meshing efficiency as one of the design variables to determine the tooth profiles. The calculation method for the meshing efficiency of planetary transmission is analyzed and the equation of the meshing efficiency is deduced. Relationships between the meshing efficiency,the radius of the pin wheel and the eccentric distance are revealed. The design constraint quations and the strength constraint quations are deduced. On the basis of this,a design procedure is laid out. Some examples using different input parameters are conducted to demonstrate the feasibility of the approach. A dynamic simulation of the rigid-flexible coupling of cycloid gears is also presented. The results show that the proposed design method is more flexible to control the tooth profiles by changing the input values of the transmission efficiency.     

国内外先进推进技术发展综述

航天运输领域发展的核心目标包括提高运载能力、降低发射成本及减少发射准备时间等。相对于传统的化学推进技术,先进推进技术采用新能源或新机理,旨在从根本上满足未来对有效载荷、发射成本和发射周期的要求。对国内外组合动力装置、核聚变动力推进、离子推进、激光推进、核子脉冲推进、太阳帆推进、磁场帆推进、布萨德喷气推进、反物质推进等先进推进技术的研究进展进行综述和可行性分析,并给出了发展启示。     

飞行器程控跟踪相控阵天线安装误差补偿技术

针对窄波束高增益相控阵天线波束指向精度要求高、安装误差对波束指向的影响无法忽略的问题,提出了一种基于光学瞄准的安装误差测量方法,给出了光学测量内容和误差修正矩阵,经某型无人机飞行测试表明,该方法可以减少由安装误差带来的波束指向偏差,对高精度波束指向具有重要意义。     

灌封用硫化硅橡胶空间适用性分析

针对航天器灌封用硫化硅橡胶,研究了其在γ射线辐照前后电学性能及力学性能的变化规律,揭示了引起性能变化的内部状态的变化及性能变化机理,同时也研究了其在空间站和载人舱中应用时的阻燃特性、逸出有害气体情况、抗菌防霉性能。结果表明,总剂量辐照后硫化硅橡胶的红外特征峰峰位和峰强基本上未产生变化,热分解行为也无变化,但绝缘性能增强,力学性能随着剂量的提升先增强后衰减,硬度不断增大然后趋于稳定,阐述了出现这些现象的原因。在载人舱中应用时应注意垂直燃烧特性及对部分细菌的抗菌性能。研究成果可为硫化硅橡胶在航天器中的使用提供参考和指导。     

超高速机械密封副离子注入与摩擦学特性研究

超高速机械动密封需满足CZ-5运载火箭伺服系统中涡轮泵可靠性及寿命指标要求。离子注入作为重要的金属材料表面改性技术,对有效改善机械密封副旋转环表面摩擦磨损特性至关重要。在对密封动环表面离子注入可行性研究的基础上,提出了对其密封副配对摩擦磨损特性进行综合验证的试验方案。通过选取常用典型石墨与旋转金属环配副进行干磨条件下的试验测试,改变线速度、端面比压,使用摩擦磨损试验机对比分析了配对摩擦副的摩擦磨损特性,系统研究了载荷和转速对密封副配对摩擦系数的影响规律,揭示其密封摩擦学特性。通过机械密封在温度应力下的工作可靠性分析以及密封副整机稳态工作性能验证,为超高速涡轮泵的寿命与可靠性试验验证提供了一个合理的、高效费比的技术途径。