基于MBD的三维数字化装配工艺设计及现场可视化技术应用

基于MBD的三维数字化装配工艺设计技术是现代航空数字化制造中的一门新兴学科,也是未来飞机三维装配工艺设计的发展趋势.该技术主要通过对DELMIA、3DVIA Composer、CAPP等工艺设计、工艺仿真软件进行客户化定制和多系统集成应用,完成基于MBD三维产品模型的工艺分离面的划分、BOM重构、工艺仿真以及三维装配指...     

面向MBD的数控加工工艺三维工序模型技术研究

正本文在分析面向MBD的复杂零件数控加工工艺设计过程的基础上,对面向MBD基于DELMIA的数控加工工艺三维工序模型技术进行了研究。MBD(Model Based Definition基于模型的定义)是一个用集成的三维模型来完整表达产品定义信息的方法,它以三维标注技术[1]为基础,详细规定了三维模型中产品尺寸、公差等的标注规则和工艺信息的表达方法[2]。基于MBD技术的三维     

A/C Three-dimensional Paralleled Assembly Process Planning and Designing Based on DELMIA

随着信息技术和三维CAD技术的飞速发展,飞机的三维设计技术日益成熟,基于MBD的飞机产品设计已经在国内航空领域广泛应用.本文论述了应用数字化企业精细制造交互式应用软件DELMIA进行基于MBD三维产品数模的三维飞机装配工艺规划、设计及装配仿真,并进行了某型机项目实施验证.     

基于模型定义技术及其实施

MBD技术体系是以MBD数据集为核心的应用体系,借助标准管理系统、标准工艺管理系统、CAD系统、工艺设计和分析以及产品数据管理等系统,通过MBD数据集集成产品的设计制造信息,并建立了一套基于MBD数据集的工艺设计分析方法和数据管理办法,使工程制造能够在脱离图纸的环境下,按照设计系统给出的内容组织框架实现对产品生产和检验的监督控制。     

基于模块的飞机消耗式三维工艺设计技术研究

随着MBD技术的发展,三维工艺设计技术逐步代替传统的二维工艺设计.结合国内外飞机研制过程中三维工艺设计技术发展现状,立足国内飞机研制实际情况,介绍了基于模块的产品数据管理方式及消耗式三维工艺设计技术原理,阐明了基于模块化的消耗式三维工艺设计管理思路和实施过程,并对应用效果进行总结.     

基于MBD的数控加工工艺设计系统

MBD模型作为制造过程中唯一依据逐步成为航空制造业的发展趋势,并已应用到CAD/CAM中。但MBD技术尚未在CAPP中展开应用,导致MBD数据集在CAD/CAPP/CAM的集成设计制造过程中无法连续传递。针对航空数控加工需求,建立了基于图层的数控加工MBD工艺模型,提出了基于MBD的数控工艺设计流程,并设计开发了基于MBD的数控加工CAPP系统,实现了UG平台上集成设计制造的MBD应用。     

基于MBD的数字化检测工艺分工技术研究

随着数字化集成制造系统的发展与应用,数字化检测技术在数字化集成制造过程中起到了至关重要的作用,工程需求日益强烈.针对数字化检测过程中缺少较合理的检测工艺分工规划的现状,结合MBD技术,提出了基于MBD的数字化检测工艺分工的相关概念和关键技术.在考虑检测成本及检测时间为约束条件的前提下,根据检测变量构造检测工艺路线函数,实现了最优检测工艺路线的生成与检测工艺分工规划的匹配.     

基于全三维模型的复合材料构件成型工艺设计系统研究

分析了复合材料构件数字化设计制造技术的发展状况,阐述了基于全三维模型的工艺设计系统的研究现状.针对复材构件成型工艺设计特点,研究了基于全三维模型的复材构件成型工艺设计系统构建技术,阐述了系统的主要功能和实现方法.在CATIA环境下开发了基于全三维模型的复材构件成型工艺设计系统,并通过多个构件的工艺设计对系统功能进行了验证.     

基于MBD的三维装配BOM重构技术

<正>本文提出基于MBD的三维装配BOM重构技术实现在BOM重构过程中的数字化。考虑到MBD作为制造过程中的唯一依据,以贯穿产品数字化定义到数字化装配工艺设计的数据流为目标,研究MBD模式下的三维BOM重构技术,为实现三维数字化装配工艺设计提供数据基础。     

基于MBD的复杂特征检测工艺规划技术研究

随着数字化集成制造系统的发展与应用,数字化检测技术作为数字化集成制造系统中的重要组成部分,工程需求日益强烈.针对数字化检测过程中缺乏合理的检测工艺的问题,在研究了传统检测方法的基础上,结合MBD技术,提出了基于MBD的三维检测工艺的关键技术.分析了影响采样点数量及其分布的主要因素,利用量化分析法推导得出了确定规则曲面、不规则平面的测量点数公式.根据采样点数量和被测元素特点,提出了自适应划分形心采样方法,获得了基于复杂特征的检测工艺规划.通过试验验证了所提出测量点数公式和自适应划分形心采样方法的合理性和准确性.     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.