金属橡胶用Cr-Ni-Mn系不锈钢丝的微观组织及力学性能研究

采用光学显微镜、扫描电镜、X射线相定量分析等技术,研究了制备金属橡胶构件用冷变形量分别为36%,64%,84%和91%所得的直径0.4mm,0.3mm,0.2和0.15mm的Cr-Ni-Mn系不锈钢丝的微组织结构和力学性能的变化规律.结果表明,冷拔钢丝中出现了形变马氏体,冷变形量为36%时的马氏体含量已达81.2%,即用于制作金属橡胶构件时奥氏体不锈钢已实际处于以马氏体为主的高强度状态,而非奥氏体状态,且马氏体数量随冷拔变形量有增大趋势;钢丝内部出现平行于拉拔方向的拉长孔洞,其体积分数随冷拔变形量的增大而增加.同时,在所用冷拔变形量条件下,不锈钢微丝的抗拉强度高达1406～2244MPa,延伸率则在13.0%～8.9%范围内变化.从而可以判断,采用上述微丝制作的金属橡胶将是以马氏体相之为主且具有微观和宏观尺度双重尺寸孔洞(孔隙)的多孔金属材料.     

40CrMnSiMoVA钢中准贝氏体组织的疲劳强度和疲劳缺口敏感性

 本文研究了超高强度40CrMnSiMoVA钢中准贝氏体组织和马氏体组织的疲劳强度。与马氏体组织相比,由贝氏体铁素体和残余奥氏体组成的准贝氏体组织,其光滑及缺口疲劳强度均较高。准贝氏体组织虽具有较低的强度,但因其中较多的残余奥氏体,结果并不损害其疲劳强度。由于该组织具有良好的强度、塑性、韧性配合,使其疲劳缺口敏感性较低。拉伸超载同时提高准贝氏体和马氏体组织的缺口疲劳强度。     

等温淬火的40CrMnSiVA钢微观组织与性能

本文研究了40CrMnSiMoVA(GC-4)钢不同等温状态的微观组织与力学性能的关系。研究结果表明:300℃等温状态的微观组织为不同形态的贝氏体、马氏体和残余奥氏体所组成的复合组织,其中的变念贝氏体改善了钢的强韧性及抗疲劳断裂性能,对提高飞机的安全可靠性具有重要的实际意义。     

Q-P工艺下超高强度300M钢的单轴拉伸规律研究

将Q-P工艺应用于300M钢,得到300M钢的单轴拉伸曲线,对拉伸各阶段规律进行分析,并采用TEM、SEM和XRD等方法,研究了Q-P工艺对300M钢性能和组织的影响。结果表明:与传统工艺相比,Q-P工艺下超高强度300M钢的强度大幅降低,弹性变形能E e降低,均匀塑性变形能E p和裂纹形成能E e+E p则大幅提高;残余奥氏体含量可提高至15.62%,并以薄膜状存在于板条间或以小块状存在于原奥氏体晶界、板条束界;其相组成为先形成的板条状马氏体+新鲜马氏体+残余奥氏体+ε-碳化物。Q-P工艺明显提高了300M钢抗裂纹形成和扩展的能力,延长了材料的均匀塑形变形阶段,推迟缩颈发生。     

残余奥氏体及其射线测量法

.4 影响强度测量精度和准确性的因素 若最终的衍射花样和强度测量满足下列条件的话,X射线衍射法测得的残余奥氏体可得到相当满意的精度和准确性。它们是:(1)每条马氏体和奥氏体的hkl线都有高的衍射强度,(2)高的峰背比(P/B),(3)各条(hkl)线之间分得足够开并有足够分辨率,(4)重叠碳化物衍射线的干涉最小,(5)整个2θ扫描范围内有低而     

渗碳钢齿轮中的残余奥氏体

渗碳钢齿轮中的残余奥氏体美通用汽车公司完成的几项试验表明，ＡＩＳＩ８６２０钢和４６２０钢含２０％一３０％残余奥氏体、３３１０钢内残余奥氏体含量达４０％时，可以明显的提高拉伸弯曲性能。在Ｆｅ一５Ｃｒ１．１２Ｃ钢中，当马氏体的百分含量超过７０％时，产生显...     

马氏体时效钢C300焊缝金属强韧化研究

在回顾马氏体时效钢焊接研究现状的基础上,针对我国最新研制的C300钢,从时效处理、合金元素和热输入对TIG焊接焊缝金属强度和韧性的影响展开系统研究,得出了这些因素对基体马氏体组织、逆转变奥氏体、金属间化合物析出相等的演变及对强度和断裂韧性的影响规律,将为我国C300的工业化焊接提供重要的技术指导。     

几项镀层国际标准工作草案介绍(续)

三、在宇航系统σ_b≤1450MP_a的钢零件、铜和铜合金零件上的镀镉 1. 应用范围 非耐蚀钢零件的抗蚀。 耐蚀钢(铁素体、马氏体或奥氏体)以及铜和铜合金与其它金属产生的接触腐蚀(耐蚀钢镀镉前应先予镀镍)。为了提高铜和铜合金     

残余奥氏体及其X射线测量法

1.1 残余奥氏体的形成 奥氏体是面心立方相,在可淬火钢中,它在ACs和ACm相界以上的温度时是稳定的,但在这些温度以下则是不稳定的。从稳定的奥氏体区进行冷却时,它可能分解或转变为几种组成物之一,其类型取决于三个因素:(1)化学成份,就是淬火时固熔体中的合金元素和碳含量(若未溶解的碳化物或其它组成物跟奥氏体共存,这可能和基本成份不同),(2)     

304奥氏体不锈钢喷丸引起的组织转变和两相残余应力测定

采用X射线衍射技术研究了304奥氏体不锈钢喷丸过程所引起的组织结构变化以及两相组织中每相的残余应力。试验结果表明,喷丸强化可使亚稳态304奥氏体材料表面发生γ→α转变,在相同的喷丸强度下转变量与喷丸弹丸种类规格关系很大,而且与喷丸时间有关;表面两相组织γ和α相各自的残余应力可采用X射线衍射应力仪进行测定,两相的残余应力数值相差很大。     

有翼高超声速再入飞行器气动设计难点问题

有翼高超声速再入飞行器是近年来的研究热点,气动设计是飞行器设计的关键。为了更清楚地认识有翼高超声速再入飞行器气动设计的难点问题,对有翼高超声速再入飞行器的发展、优势及总体任务剖面进行了介绍,从5个方面详细介绍了该类飞行器气动设计的难点问题,包括多约束复杂面对称气动布局设计、高温真实气体效应对气动特性影响、天地差异与天地换算方法、反作用控制系统(RCS)喷流干扰对气动特性的影响以及气动数据不确定度等,简要阐明了这些难点问题对总体设计的重要性以及初步的解决思路,为有翼高超声速再入飞行器气动设计提供了一些参考。     

Simulation and Analysis of Crashworthiness of Fuel Tank for Helicopters

Crashworthiness requirement of fuel tanks is one of the important requirements in helicopter designs. The relations among the protection frame, textile layer and rubber layer of the fuel tank are introduced. Two appropriate FE models are established, one is for an uncovered helicopter fuel tank without protection frame, and the other is for fuel tank with protection frame. The dynamic responses of the two types of fuel tanks impinging on the ground with velocities of 17.3 m/s are numerically simulated for the purpose of analyzing energy-absorbing capabilities of the textile layer and protection frame. The feasibility of the current crashworthiness design of the fuel tank is examined though comparing the dynamic response behaviors of the two fuel tanks.     

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.      

突破技术趋同，波音再现竞争优势

 波音公司面临着来自空客公司的巨大挑战,企业战略性创新才是公司成功的关键。为此波音公司的全部战略性研究集中在扩大产品的差异性上,体现在3个方面：电子化（e-Enabled）运营环境、整体复合材料机身部件的制造技术和支持波音787客机的全球协同环境（GCE）。     

ν-gap度量及其在飞行控制律评估中的应用

 传统控制律评估方法主要用于单输入单输出（SISO）系统，且对模型参数摄动考虑不够全面,针对这些不足，研究了ν-gap度量方法。在介绍系统广义稳定裕度相关概念的基础上，给出了ν-gap度量的定义、特点和性质以及近似摄动模型的计算，提出ν-gap度量评估控制律的步骤。实例结果表明，该方法不仅克服了上述传统评估方法的缺陷，而且还有根据所求的各摄动影响情况忽略影响小的元素，以减少计算量及可以找到最坏情况下的参数摄动组合等优点。     

临近空间飞行器测控与信息传输系统频段选择

 临近空间飞行器是高性能信息化武器平台,测控（TT&;C）与信息传输系统是其信息保障的核心,而选择合理、可行的频段是展开系统设计的前提和基础。频段选择影响到整个技术方案的制定,是一个需综合考虑、影响深远并具有战略意义的关键问题,从国际电联（ITU）国际标准、高速数传、接收信噪比（SNR）、“三抗”、超视距中继、黑障、雨衰以及设备研制成熟度8个方面全面、细致论证了近空间平台测控系统的频段选择问题,最终得出在视距链路中以Ka频段为宜,在超视距链路中以Ku/Ka双频段为宜的结论。     

基于弯曲激波压缩系统的高超声速进气道反设计研究进展

总结了近十年来弯曲激波压缩研究的主要成果。提出了弯曲激波压缩系统的新概念,即利用特殊设计的楔形弯曲压缩面或空间弯曲压缩面,产生一系列与前缘弱激波相互交汇或叠加的压缩波系,从而使前缘激波弯曲,形成特殊的弯曲激波,它与波后的等熵压缩波来共同完成对气流的压缩。在此基础上,实现了由给定出口气动参数的超声速内流道反设计,实现了由给定压缩面压力分布和给定压缩面马赫数分布要求的型面反设计,实现了由给定激波波面的压缩型面反设计。研究证明,弯曲压缩面-弯曲激波压缩系统具有良好的综合气动性能,为高性能高超声速进气系统的气动设计提供了一种全新的设计方法。     

Integrated Entry Guidance for Reusable Launch Vehicle

A method for the implementation of integrated three-degree-of-freedom constrained entry guidance for reusable launch vehicle is presented. Given any feasible entry conditions, terminal area energy management interface conditions, and the reference trajectory generated onboard then, the method can generate a longitudinal guidance profile rapidly, featuring linear quadratic regular method and a proportional-integral-derivative tracking law with time-varying gains, which satisfies all the entry corridor constraints and meets the requirements with high precision. Afterwards, by utilizing special features of crossrange parameter, establishing bank-reversal corridor, and determining bank-reversals according to dynamically adjusted method, the algorithm enables the lateral entry guidance system to fly a wide range of missions and provides reliable and good performance in the presence of significant aerodynamic modeling uncertainty. Fast trajectory guidance profiles and simulations with a reusable launch vehicle model for various missions and aerodynamic uncertain-ties are presented to demonstrate the capacity and reliability of this method.     

Experimental Study on Effects of Fuel Injection on Scramjet Combustor Performance

In order to investigate the effects of fuel injection distribution on the scramjet combustor performance, there are conducted three sets of test on a hydrocarbon fueled direct-connect scramjet test facility. The results of Test A, whose fuel injection is carried out with injectors located on the top-wall and the bottom-wall, show that the fuel injection with an appropriate close-front and centralized distribution would be of much help to optimize combustor performances. The results of Test B, whose fuel injection is performed at the optimal injection locations found in Test A, with a given equivalence ratio and different injection proportions for each injector, show that this injection mode is of little benefit to improve combustor performances. The results of Test C with a circumferential fuel injection distribution displaies the possibility of ameliorating combustor performance. By analyzing the effects of injection location parameters on combustor performances on the base of the data of Test C, it is clear that the injector location has strong coupled influences on combus- tor performances. In addition, an inner-force synthesis specific impulse is used to reduce the errors caused by the disturbance of fuel supply and working state of air heater while assessing combustor performances.     

(高)超声速流动试验技术及研究进展

近年来,与高速飞行器相关的(高)超声速流动受到了极大的关注。这类流动所具有的非定常性、强梯度和可压缩性对试验方法和风洞设计技术提出了挑战。超声速纳米示踪平面激光散射(NPLS)技术是由作者所在团队研发的非接触光学测试技术。它能够以较高的空间分辨率来揭示超声速三维流场的一个瞬态剖面的时间解析的流动结构。介绍了NPLS技术以及基于NPLS开发的密度场测量、雷诺应力测量和气动光学波前测量等方法,并回顾了这些技术在超声速边界层、超声速混合层、超声速压缩拐角、激波/边界层相互作用和光学头罩绕流等流动中的应用,清晰地再现了边界层、混合层、激波等典型流场结构及其时空演化特性。另外,为了模拟和研究高空大气条件下边界层自然转捩和超声速混合层的转捩特性,介绍了高超声速静风洞、超-超混合层风洞的设计技术以及层流化喷管的设计方法。