钣金零件橡皮囊液压成形技术研究和应用现状

橡皮囊液压成形是钣金成形的主要方法之一,在飞机上有大量橡皮囊液压成形的钣金零件。橡皮囊液压成形工艺制造水平的提升,能大幅提高钣金零件的表面质量和疲劳寿命,从而改善飞机的整体性能。针对国内外橡皮囊液压成形工艺的研究现状进行总结,介绍了橡皮囊液压成形工艺的特点及应用领域,重点从钣金材料成形性能及工艺参数、成形缺陷、有限元仿真建模等方面综述了橡皮囊液压成形工艺的相关研究成果,对今后开展橡皮囊液压成形技术研究提供指导。     

飞机橡皮囊成形零件毛坯精确预示方法研究

 橡皮囊成形是飞机钣金零件成形的主要方法之一,其初始毛坯形状的预示是橡皮囊成形中的一个难点问题。针对橡皮囊成形的工艺特点,提出了一种基于一步逆成形有限元法的飞机橡皮囊成形钣金零件毛坯快速精确预示方法。首先将设计好的飞机钣金零件作为最终构形,然后采用一步逆成形有限元法进行初始毛坯的快速反向模拟,最后将通过该方法获得的毛坯外形应用到实际飞机钣金橡皮囊成形中,实验结果表明该方法可以快速精确地预示出飞机橡皮囊成形钣金零件的初始毛坯形状。     

飞机框肋零件橡皮囊液压成形回弹研究综述木

回弹是影响飞机框肋零件成形质量的主要因素之一,通过分析影响框肋零件回弹的主要因素,对框肋零件橡皮囊液压成形工艺的回弹预测及控制研究情况做了综述,并将预测方法归类为解析法、有限元法、人工神经网络法和试验法4种,最后总结分析了框肋零件橡皮囊成形零件回弹控制方法的发展方向.     

飞机框肋零件橡皮囊液压成形回弹研究综述

回弹是影响飞机框肋零件成形质量的主要因素之一,通过分析影响框肋零件回弹的主要因素,对框肋零件橡皮囊液压成形工艺的回弹预测及控制研究情况做了综述,并将预测方法归类为解析法、有限元法、人工神经网络法和试验法4种,最后总结分析了框肋零件橡皮囊成形零件回弹控制方法的发展方向.     

橡皮囊液压成形回弹补偿技术比较分析

橡皮囊液压成形工艺是航空钣金成形的主要方法之一,而回弹是影响其产品制造精度的主要缺陷。为提高航空钣金零件制造精准化制造水平,国内开展了大量的研究和实践,但各种方法的工程化应用程度并不理想。针对基于数值模拟的回弹预测方法和基于零件几何特征的快速回弹补偿方法进行综述,对比分析了两种方法的优缺点,并结合航空企业工程化应用实际需求提出将两种方法相结合的解决方案。     

飞机橡皮囊成形钣金零件毛坯预示系统开发

<正>基于一步逆成形有限元法的橡皮囊成形初始毛坯设计系统RBSE可以快速准确地预示出橡皮囊成形钣金件所需的毛坯外形,指引下料,有效减少实际生产中手工修整量,缩短生产周期,提高效率。构成飞机产品外形、结构和内装的主要零件基本都是钣金件,其形状复杂、质量控制严格,且对成形后的零件有明确的力学性能和物理性能的要求,所以加工较为困难。目前,航空工业主要采用橡皮囊成形方法来成形钣金件。这是由于橡皮囊成形中利用橡皮作为弹性凸模,用高压液体作为传压介质,在压     

橡皮囊成形的有限元模拟

利用大型通用有限元软件Abaqus处理非线性力学问题的优势,采用显式算法模拟了橡皮囊成形的全过程.算例表明,采用Abaqus处理橡皮囊成形可得到满意的结果.     

铝合金薄蒙皮零件成形工艺

通过分析铝合金薄蒙皮零件的结构及其成形工艺特点,拟定针对性工艺措施,设计了合理的模具结构,实现了该类零件在橡皮囊液压成形机上的液压成形。     

橡皮囊成形模具快速设计方法研究

作为飞机钣金件主要成形方法之一的橡皮囊液压成形,具有效率高、成形后零件表面质量好等优点.随着飞机制造业的发展,橡皮囊液压成形在飞机钣金件成形中所占的比重也越来越大.随着CAD技术的发展,基于数字化设计和数字化制造技术的支持,航空企业已广泛应用CAD/CAE等先进技术来实现橡皮囊成形模具的结构设计与优化[1],从模具三维造型设计到模具的数控生产,数字化技术提高了模具的设计与生产精度,缩短模具设计周期,提高企业生产效率,使我国航空企业步入高效生产、精益生产的时代.由于航空钣金件数量大、类型多、模具结构形式多变,橡皮囊液压成形模具在很大程度上仍然依赖设计人员的经验,模具的快速设计已成为模具设计中的瓶颈.     

橡皮囊液压成形模具快速设计方法及实现

成形模具设计在整个飞机钣金制造体系中起着承上启下的重要作用,快速化、专业化以及精确化是其发展趋势。本文提出的基于知识的设计方案检索、设计流程导航、设计信息快速提取、结构参数化驱动设计等多种方法相结合的解决方案提供了一种实现橡皮囊液压成形模具快速设计和降低设计经验要求的有效途径。     

基于飞机油箱模型形状特征油量测量切片步长选择方法研究

 在分析飞机数字式油量测量过程中目前广泛使用的切片法油量测量原理的基础上,针对现有的定步长切片法无法得到准确、可靠的燃油质量特性数据库的缺陷,结合对飞机油箱模型形状特征的分析,提出了基于飞机油箱模型形状特征的油量测量切片步长选择方法。此方法包括切片步长整体和局部选择两个过程,整体选择以实现相邻两切片平面所夹油箱模型体积近似相等为目的来确定切片步长,以体现油箱模型截面整体变化规律;局部选择以设计切片平面与截面突变平面重合或尽可能接近的方式,突出油箱截面的局部变化特征。实验结果表明：该切片步长选择方法较定步长方法能够建立更为合理、可靠的燃油质量特性数据库,从而提高了油量测量精度。     

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.      

二维翼段颤振的μ控制

 采用超声电机作为作动器来实现含控制面的翼段颤振鲁棒抑制。针对作者设计的二维翼段颤振主动抑制系统，通过理论与实验相结合的方法，建立了考虑沉浮方向阻尼和作动器模型参数不确定性的控制系统模型，设计了μ控制器，并对控制器做了降阶处理。数值仿真和风洞试验表明，μ控制器可有效地抑制颤振的发生，将颤振临界速度提高23.4%。相对于H_∞控制器，μ控制器的控制效果和鲁棒性更好。     

Abnormal Shape Mould Winding

为解决网格化芯模的缠绕问题,本文提出了复合材料面片缠绕机理;接着详细分析了面片缠绕过程中的芯模凹曲面上纤维滑线和架空现象,应用微分几何曲面理论和空间几何理论,提出判据及其解决方案;最后,针对飞机发动机进气道的缠绕成型,编制缠绕控制程序并进行相应的实验,验证了面片缠绕方法的可行性。     

基于H∞性能指标的质量矩拦截弹鲁棒控制

 以所建立的质量矩拦截弹数学模型为基础，利用微分几何的反馈线性化理论，得到一个解耦线性系统，考虑到拦截弹的鲁棒性要求和3个滑块的协调控制问题，提出采用双回路的设计方法，内回路采用线性二次调节器（LQR），外回路采用考虑混合灵敏度问题的H_∞控制设计。仿真结果证明了该方法动态性能满足设计要求，同时对系统参数的不确定性具有较强的鲁棒性。     

航天器返回地球的气动特性综述

航天器返回地球的飞行过程中,气动特性是实现将宇宙飞行速度减到落地前速度、保证再入飞行得到有效控制以及再入防热安全可靠的关键因素。针对简单旋成体气动外形、半弹道式再入控制、烧蚀防热类返回航天器,综述了返回地球过程中变化的空气流域特性、航天器周围的气体绕流环境、空气与航天器作用产生的动力学与热效应等。系统地给出了该类航天器的再入气动特性参数与飞行性能的共性规律,包括:气动阻力与再入减速、气动升力与再入轨迹控制、配平攻角与飞行稳定性、气动加热与防热,以及再入过程中不同气动特性航天器、气象条件变化等对再入飞行性能的影响规律。为航天器开展返回飞行过程的跨流域气动性能工程研制提供设计参考。     

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.     

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 ℃).     

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.