四核钴铁簇合物Co_3Fe(mp)_4(Hmp)(PBu_3~n)_3的FAB质谱研究(Hmp=2-巯基苯酚,Pbu_3~n=三正丁基膦

本文选择质量为1460μ且金属原子具有三种不同配位环境的四核钴铁簇合物Co3Fe（mp）4（Hmp）（PBu）3（Hmp＝2-巯基苯酚,PBu＝三了基膦）为研究对象,以快原子轰击软电离方法,研究其质谱断裂行为及其可能的裂解途径。     

大电机轴电压研究

分析了大电机轴电压的性能,产生原因,检测方法和预防措施。     

Studying single nanocrystals under high pressure using an x-ray nanoprobe

In this report, we demonstrate the feasibility of applying a 250-nm focused x-ray beam to study a single crystalline NbSe(3) nanobelt under high-pressure conditions in a diamond anvil cell. With such a small probe, we not only resolved the distribution and morphology of each individual nanobelt in the x-ray fluorescence maps but also obtained the diffraction patterns from individual crystalline nanobelts with thicknesses of less than 50 nm. Single crystalline diffraction measurements on NbSe(3) nanobelts were performed at pressures up to 20 GPa.     

液压电磁阀故障机理分析与瞬态特性仿真

液压电磁阀作为液压系统中的关键元件,是电控系统和液压系统的控制中枢,在大型武器装备中使用数量多、分布广,且故障率较高,对其实施在线监测诊断对于确保液压系统的正常运行十分重要.在收集整理电磁阀常见故障的基础上,深入研究了各类故障的发生机理;通过对电磁阀常见故障和特征信号的可测性分析,提出了一种基于磁场和振动敏感的电磁阀非介入式测试诊断技术;通过对电磁阀工作过程中的磁路分析和阀芯受力分析,建立了电磁阀的瞬态响应仿真模型,并进行了实验验证,为电磁阀故障的快速检测诊断奠定了基础.     

端面周向波度密封中流场的数值模拟

建立端面周向波度密封密封端面间液膜流场的数值模型,采用计算流体力学软件FLUENT对密封间隙中的液膜进行三维数值模拟,得到液膜流场的压力分布,求得密封的泄漏量、开启力和刚度等密封特性参数,分析密封几何参数(如波幅、波数、密封环坝区的宽度与密封环宽度之比)对密封性能的影响.结果表明:随着液膜厚度的增加,开启力减小,泄漏量增大;密封几何参数对密封特性参数的影响存在一定的规律,如波幅越大、波数越多,密封环端面的流体动压效应越明显,而随密封环坝区的宽度与密封环宽度之比的增加,开启力、泄漏量和刚度都减小.     

Numerical simulation on the local stress and local deformation in multi-point stretch forming process

Multi-point stretch forming (MPSF) is a new flexible forming technique to form aircraft outer skin parts. The multi-point stretching die (MPSD) replaces the traditional fixed shape stretching die, and the sheet metal is formed over a MPSD composed by the punch element. The MPSD is a discontinuous surface of discrete stretching die, and the stress concentration and local strain occur on formed parts. These lead to generate dimples on the surface of formed part. In this paper, a series of numerical simulations on MPSF processes for stretching parabolic cylindrical, spherical, and saddle-shaped parts were carried out. The local stress and local strain in thickness distribution of MPSF part were analyzed by dispersed the blank into solid elements. The forming results of MPSF were compared with those that use traditional stretch forming, and the influences of thickness of elastic cushion and the size of punch element on the stress concentration and local strain were surveyed. The simulation results show the distribution of local stress and local deformation in different layers, and the elastic cushion and the small size of punch element can reduce the stress concentration and local deformation. The results may understand the stress distribution on the sheet and prevent the defect of dimple.     

Cu-P-Cr-Ni-Mo耐候钢高温变形奥氏体的动态再结晶

用Gleeble-3500热模拟试验机研究了Cu-P-Cr-Ni-Mo耐候钢(%:0.10C、0.075P、0.65Cr、0.22Ni、0.43Mo、0.28Cu)在应变速率0.01～1 s-1、温度850～1150℃时的动态再结晶行为,得出该钢奥氏体区的真应力-真应变曲线和动态再结晶图,分析了变形参数对峰值应力的影响和不同热变形时耐候钢的动态再结晶体积分数与真应变的关系,建立了该钢的奥氏体热变形方程、动态再结晶临界条件回归方程和奥氏体动态再结晶体积分数数学模型。结果表明,随变形温度升高,峰值应力下降;随变形速率增大,峰值应力升高;随Z参数增大即变形温度降低,应变速率增加,发生再结晶的临界应变εc和发生完全再结晶的应变εs均呈线性增加。     

人体温度数字式无线检测微机电系统的设计与研制

通过理论分析和实验研究,提出了一种用于人体温度数字式无线检测的微机电系统的设计方法。针对人体的特殊使用条件及环境,本着微体积可靠性高等设计原则,分别讨论了温度传感器的选择和设计、封装外壳的设计和无线温度信号发射与接收的设计,并研制出符合设计要求的微机电系统,对系统进行了体外温度测量实验,实验结果表明系统设计可行。     

冷拉伸滚压成形新工艺参数研究

采用ADINA有限元软件对高强度柔性螺栓在此加工工艺中定义材料性能,建立滚压模型,划分网格,约束边界条件,施加载荷.对在不同拉力,滚压量两个实验参数下进行冷拉伸滚压新工艺加工模拟仿真,得到端面中点的最大应力,有效应力及位移与时间函数的图形,并分析结果得出最有利于加工的工艺参数.为下一步做轴类冷拉伸滚压成形实验提供重要的实验参数.     

大型机械结构的分层动态优化方法

针对大型机械结构动态优化设计维数高,同时涉及外形尺寸和截面尺寸两类变量,采用整体优化策略,存在收敛困难的问题,提出了采用分层优化结合子结构方法的机械结构动态优化策略。以有限元方法为基础,将外形尺寸和截面尺寸分离到两个相对独立的设计空间,从而将整体优化问题分解为整体层优化和局部层优化两个子优化问题。在整体层以整体结构动态特性最优为目标,完成对外形尺寸的优化;在局部层以子结构动态特性最优为目标,完成对截面尺寸的优化;两层优化交替进行直至问题最后收敛。某型大跨自动扶梯金属结构的动态优化工程实例表明,该方法优化效果良好且优化效率高。