CT local reconstruction of solid rocket motor based on PI-POCS-TVM

In order to test the defects of solid rocket motor (SRM) accurately and efficiently, the computed tomography (CT) inspection scheme for SRMs defects was investigated and a CT local reconstruction algorithm called prior information projection onto convex sets total variation minimization (PI-POCS-TVM) was developed. The SRM was first inspected by industrial CT (ICT) to generate a low resolution SRM image used as the prior information, then high resolution local inspection was carried out for SRM's defects. To validate the effectiveness of the CT inspection scheme for SRMs defects, one SRM was inspected by a narrow fan beam ICT system. Filtered back projection (FBP) algorithm, POCS, POCS-TVM and PI-POCS-TVM algorithms were applied to reconstruct CT images. The performance of these algorithms was also compared. Results demonstrated the effectiveness of the CT inspection scheme for SRM's defects. Moreover, the PI-POCS-TVM algorithm has better local reconstruction image quality than the other three algorithms, showing great significance for accurate measurement of SRM's defects.      

战术导弹用MEMS陀螺仪研制进展及关键技术

MEMS陀螺仪具有体积小、质量轻、启动快、可靠性高、价格低、易于大批量生产、能承受恶劣环境条件等突出优势,可广泛应用于防空导弹、反坦克导弹、便携式导弹、航空制导炸弹等制导武器.介绍了MEMS陀螺仪的基本原理、发展现状,分析了战术导弹对MEMS陀螺仪的应用需求,指出了MEMS陀螺仪在战术导弹型号应用中需解决微机械加工工艺、全温性能指标、复合力学环境等关键技术问题,对MEMS陀螺仪在战术导弹中的应用具有指导意义.     

CFD优化火箭涡轮泵间隙密封静动态特性计算模型

Bulk flow模型被广泛应用于计算火箭涡轮泵间隙密封泄漏量和动力学系数,然而半经验性的边界条件和阻力系数会降低模型的准确性。CFD数值模拟近年来被应用于间隙密封的研究,表现出优越的性能,然而瞬态计算动力学系数效率较低。结合两种方法的优势,利用CFD稳态流场分布,计算密封间隙边界条件,同时基于泄漏量相等优化目标,确定Bulk flow模型中阻力系数,并采用有限单元法数值求解优化后Bulk flow方程组。与文献中数值结果对比,数值结果与试验结果更加吻合,主刚度和交叉刚度最大偏差率为10.15%和7.54%。     

三维随机振动环境下MEMS加速度计输出特性分析

对MEMS惯性测量单元进行了三维随机振动试验,初步探讨了MEMS惯性测量单元在三维振动试验条件下的故障模式:3个轴的MEMS加速度计均出现了零位偏移,该现象在单轴振动试验环境中并没有出现.从理论和仿真分析了该现象产生的机理,提出了解决办法并通过了试验验证.结果表明:三维振动比单轴的振动更能接近真实的振动环境,结构被激发的模态更丰富.通过采取措施,减小了加速度计的零偏值,从9.4m/s2降至1.97m/s2.     

超精密直线度测量技术

介绍了一种结构简单,但性能稳定、精度高的电感传感器.并介绍了操作方便、置信度高、可用于短工件测量的直线度空间域的组合测量方法.利用它们进行超精密直线度测量,具有良好的效果.     

非线性下降因子智能单粒子算法

下降因子是基本智能单粒子算法中一个非常重要的参数,控制着算法由全局搜索转向局部搜索的速度,平衡算法的全局和局部搜索性能。基本的智能单粒子算法采用定值下降因子,不能随着计算的需要实时作出调整,对算法的性能造成了一定的不利影响。在基本的智能单粒子算法基础上,通过引入最大下降因子和控制因子这两个参数,提出一种基于非线性策略下降因子智能单粒子算法,成功地使得下降因子能够根据计算的需要而实时改变。函数测试和气动优化结果表明,改进算法能在相同的计算规模下获得比基本智能单粒子算法更好的解。     

等静压技术在材料加工领域的应用现状

主要阐述了等静压技术在金属、金属基复合材料、无机非金属材料以及聚合物材料等领域的应用现状,分析了等静压技术与3D打印复合成型技术的发展趋势,介绍了国内外等静压仿真模拟技术的研究进展,并对等静压技术的发展趋势提出展望。     

Multi-scale thermodynamic analysis method for 2D SiC/SiC composite turbine guide vanes

Ceramic Matrix Composite (CMC) turbine guide vanes possess multi-scale stress and strain with inhomogeneity at the microscopic scale. Given that the macroscopic distribution cannot reflect the microscopic stress fluctuation, the macroscopic method fails to meet the requirements of stress and strain analysis of CMC turbine guide vanes. Furthermore, the complete thermodynamic properties of 2D woven SiC/SiC-CMC cannot be obtained through experimentation. Accordingly, a method to calculate the thermodynamic properties of CMC and analyze multi-scale stress and strain of the turbine guide vanes should be established. In this study, the multi-scale thermodynamic analysis is investigated. The thermodynamic properties of Chemical Vapor Infiltration (CVI) processed SiC/SiC-CMC are predicted by a Representative Volume Element (RVE) model with porosity, leading to the result that the relative error between the calculated in-plane tensile modulus and the experimental value is 4.2%. The macroscopic response of a guide vane under given conditions is predicted. The relative error between the predicted strain on the trailing edge and the experimental value is 9.7%. The calculation of the stress distribution of micro-scale RVE shows that the maximum value of microscopic stress, which is located in the interlayer matrix, is more than 1.5 times that of macroscopic stress in the same direction and the microscopic stress distribution of the interlayer matrix is related to the pore distribution of the composite.     

行星滚柱丝杠动力学特性分析及试验研究

准确的舵机模型是舵机系统控制及颤振分析的关键,为实现舵机模型快速而准确的控制,需要建立高精度的行星滚柱丝杠动力学模型。依据赫兹接触理论建立了考虑螺纹啮合刚度的行星滚柱丝杠动力学力学模型,搭建行星滚柱丝杠动力学特性试验台。试验结果表明:行星滚柱丝杠前两阶固有频率试验结果分别为195Hz和747Hz,与仿真结果误差小于6.7%,验证了模型准确性。研究了螺纹接触角和滚柱半径对行星滚柱丝杠啮合刚度以及行星滚柱丝杠的前两阶固有频率的影响。结果表明:螺纹接触角增加,会导致行星滚柱丝杠的螺纹啮合刚度及其第一、二阶固有频率增加;而滚柱半径的增加同样会使行星滚柱丝杠的螺纹啮合刚度增加,但其第一、二阶固有频率会在半径为某特定值时达到最大。     

压阻式压力传感器及其应用电路设计

介绍了压阻式传感器的工作原理以及相关应用电路，并给出了一个应用示例加以说明。