航空发动机涡轮出口总温测控系统在线校准方法

以气流温度测量原理为基础,简述了航空发动机试车台涡轮出口总温测控系统的现场校准方法,分析航空发动机试车台涡轮出口总温测控系统的现场校准存在的缺陷,提出了在现场校准的基础上,通过在校台用航空发动机上安装精密抽气式热电偶组, 对航空发动机试车台涡轮出口总温测控系统进行在线校准的方法,同时给出了测量不确定度的评估.     

离子氮化炉的精确测控温

根据离子氮化设备测控温的特殊性,设计了一种操作简单、使用方便、测温准确并能自动控涅的方式,即由双波比色温度仪、热电偶、测温头及其它测控温仪表组成的系统和用此系统测温、校温、自动控温的方法,论述了有关仪表的改装。考察了氮化工艺参数、村质对测控温精度的影响,指出这种测控温方式有明显的优越性,不仅精度高,而且可以测量炉内工件温度的均匀性及准确控制工件某一部位的温度。     

大型板材真空退火炉多温区均温性控制研究

针对大型稀有金属板材真空退火炉加热工艺特点以及炉室容积大、加热温区多、检测与控制不一致性等,提出基于Fuzzy-PID的控温与均温策略,并进行了实际控温与均温控制测试分析。生产运行表明,系统实现温度高精确度和多温区高均温性的控制,对提高稀有金属板材的真空退火质量具有重要意义。     

高性能恒温环境的设计及MAX1978性能测试

设计一种基于半导体制冷器的恒温控制系统.温度测量传感器采用标定测量不确定度为6.6mK的热电偶.主控温系统和辅助控温系统核心采用专用芯片MAX1978,主控温器设计目标是保障测量环境内无热源时,环境内温场稳定度和均匀度达到±0.01℃,测量环境内存在热源时,通过调节辅助控温器以获得较好的温度分布.性能测试结果表明MAX1978控温稳定度优于0.003℃/h,控温分辨率优于0.01℃,温度与MAX1978的输入电流间存在一一对应关系.     

锌点炉控温装置的数字化改造

介绍了锌点炉控温设备的改造,成功研制出控温精度高、稳定性好的锌点炉自动控温装置的全过程.着重叙述了控温仪表的程序如何与相变曲线相配合、配套电路的设计以及如何与控温仪表相配合形成合适的加热电流等关键问题.     

高精度梯度控温系统应用研究

为满足某型号航天产品热真空试验中梯度控温需求,设计了一套高精度梯度控温系统.系统由热沉、加热器及配套的控温系统等组成,可实现载荷等产品梯度控温需求,控温精度可达±0.2℃.本文介绍了该系统控温结构的设计、温控结构框架、PID控温原理.采用该系统对产品分区进行梯度控温试验,试验中系统运行稳定可靠,结果表明该系统满足产品分...     

基于双半导体制冷器的谐振式露点仪主控温系统设计

针对高精度石英谐振式露点仪中所涉及的露点温度双闭环跟踪控制的问题,本文提出了一种基于双半导体制冷器的主控温系统,该系统采用STM32作为主控芯片,利用PID控制算法通过DAC分别对两路半导体制冷器进行驱动和温度跟随控制。该系统在-15~15 ℃温度范围内进行了控温效果试验,结果显示该主控温系统线性制冷速率误差不高于10%,连续线性控温精度高,可为基于双制冷面的高精度石英谐振式露点仪实现双闭环露点跟踪测量提供有效的温控解决方案。     

4.2—280K宽温区低温电磁驱动式热开关实验研究

为了在低温温度标定系统中实现超宽温区控温,研制了一种以电磁力驱动的主动机械式热开关,相比常规的气隙式或者材料热胀冷缩式热开关,具有工作温区宽、响应速度快等优点。以一台两级G-M低温制冷机为冷源,搭建了温度低至4.2 K的低温热开关性能试验台。通过升降温过程中的控温对比实验,测得该热开关在50 K时闭合热导为1.5 W/K,断开热导为1.2 m W/K,开关比为1 250;在240 K时闭合热导为0.4 W/K,断开热导为0.5 m W/K,开关比为80。     

一种带有校温孔的控温热电偶设计及其在现场校温中的运用

本文介绍了一种带有校温孔的控温热电偶设计及其在现场校温中的运用.通过对现场热处理炉的现状分析,提出了一种新的现场校温方法,设计出一种带校温孔的新型热电偶,并介绍了它在实际现场中的运用,进一步验证了它的实用性.     

高纯氮终端纯化装置用智能控制仪

用单片微机对高纯N_2终端纯化装置进行测控,具有精度高,自动化程度高及体积小,成本低等优点。叙述的智能控制仪充分利用单片微机软硬件,对测量信号进行线性补偿处理,并采用PID算法进行控制;允许操作人员设置各种控温参数及报讯时间;不仅可用数码管显示11种运行参数,还可用灯光显示8种运行状态;此外,还具备超温声光报警功能;在抗干扰方面也有独到的处理。从系统要求及控制方法、硬件配置、软件设计等方面进行论述,为化工设备自动化提供了可借鉴的方法和思路。     

Use of small specimen creep data in component life management: a review

Small specimen creep testing techniques are novel mechanical test techniques that have been developed over the past 25 years. They mainly include the sub-size uniaxial test, the small punch creep test, the impression creep test, the small ring creep test and the two-bar creep test. This paper outlines the current methods in practice for data interpretation as well as the state-of-the-art procedures for conducting the tests. Case studies for the use of impression creep testing and material strength ranking of creep resistant steels are reviewed along with the requirement for the standardisation of the impression creep test method. A database of small specimen creep testing is required to prove the validity of the tests.     

Anomalous creep behaviour of a Ni-22 at % Cu alloy and the miscibility gap

The purpose of this study is to understand the anomalous creep behaviour of Ni-22 at % Cu alloy at the suggested critical miscibility gap temperature, below 598 K (0.36T _m). The Cu-Ni system is classified as a class II solid solution at temperatures above 0.4T _m, and it is also experimentally verified by the authors that the characteristic creep behaviour of the alloy used for this work is that for a class II solid solution. However, at low temperatures, this particular alloy shows different creep behaviours, with small stress increment in the steady state, sigmodial creep deformation is observed while with large stress increases normal primary creep occurs. When unloading the stress during creep and ageing at the test temperature, no softening due to recovery is observed but the same creep rate is achieved. The activation energy of the creep for the quenched and aged specimen is anomalously high, 326 kJ mol^–1, however, for the annealed specimen it was 167 kJ mol^–1 which is the same for that of pipe diffusion. On the basis of the observed experimental results and proper analysis, it is hypothesized that, at the test temperature, the possible formation of the solute clustering is responsible for the high activation energy and stress exponent for the creep deformation. Using the mechanical testing, creep test, it is experimentally verified that Cu-Ni system has a miscibility gap at low temperature.     

持久蠕变试验自动巡回测温软件设计

通过对持久蠕变试验测温软件系统的设计，使原测试设备控温的精度和可靠性得到了提高，同时也提高了试验员的劳动效率，减轻了劳动强度。     

3D-C/SiC复合材料拉伸蠕变损伤和蠕变机理

对3D-C/SiC复合材料进行拉伸蠕变试验,蠕变进行一段时间后,用扫描电子显微镜(SEM)观察试样表面的变化,同时测量试样的共振频率.结果表明,3D-C/SiC除通常CMC所产生的蠕变损伤外,纤维束滑动,纤维束之间的夹角变化,孔隙变形,部分孔隙表面空间位置改变,孔隙表面产生基体微裂纹,损伤在纤维束交叉处更为集中,这些可作为3D-C/SiC蠕变变形的独特机理.电阻和模量的相对变化与蠕变曲线相似,因此电阻和模量都可表征C/SiC材料的蠕变损伤,作为损伤变量.该材料的蠕变属于损伤引起.     

A hybrid experimental-numerical procedure for determining creep crack growth rates

Creep crack growth in a nickel base superalloy at elevated temperatures was analyzed through a hybrid experimental-numerical (HEN) procedure. This HEN procedure consisted of simultaneous use of creep crack growth test displacement data from center cracked plate specimens of IN-100 at 732°C and a theoretical finite element model of the test specimen.A method for getting creep crack growth behavior solely from high resolution displacement measurements, in conjunction with a cracked specimen model which utilizes realistic constitutive relationships, has been developed. The constitutive law, in the form of the Bodner-Partom material model, was especially tailored to the nickel base superalloy studied which displays time-dependent nonlinear inelastic behavior at elevated temperatures. It has been demonstrated that the technique can be applied where crack extension is very small and could not otherwise be resolved by conventional experimental crack measuring techniques. This method provides realistic monotonically increasing crack growth values. The predictions agreed to within 10% of post-test measurements.     

HTR-10燃料元件装卸控制模拟装置的研制

在研制以ＬＣ－ＩＰＣ为核心的高温气冷实验堆燃料元件装卸控制系统的过程中,设计了燃料元件装卸控制模拟装置,文中介绍了装置结构,现场信号及执行模拟运行实现方式。实现了燃料元件装卸循环过程模调试控制、状态监控、等功能。     

Impression creep test of a P91 steel: a round robin programme

The process of standardisation of small specimen creep testing techniques, specifically the impression creep test requires the repeatability of the test method. In this study it is accomplished through a round robin programme involving four different labs which have slightly different test set-ups adhering to predefined recommendations stated in previous work. The labs all conducted the same stepped stress test on a reference heat of grade 91 power plant steel and the displacement traces of the tests are analysed to outline the effects of different test set-ups and their efficacies. Main differences are in temperature control and loading application and control.     

基于声辐射模态的Η∞解耦控制器设计

根据声辐射模态的特点提出四组控制力布置方法。在此基础上采用Η∞算法设计了四个独立的控制器,控制前四阶声辐射模态的伴随系数使辐射声功率最小化。该方法能够将复杂的四输入/四输出控制系统转化为四个独立的单输入/单输出系统,从而使得每组控制力可以单独控制对应阶声辐射模态的伴随系数。模拟仿真结果表明,该方法能够实现系统解耦控制,使辐射声功率明显降低。     

缓冲材料蠕变特性测试系统设计

目的介绍一种缓冲材料蠕变测试系统的设计方法,该系统包括测试装置的硬件设计和相应的测试软件开发。方法设计一种新的缓冲材料蠕变特性的测试装置,并用Lab VIEW软件开发其测试软件系统,采用PC机自带的声卡作为数据采集卡,配合传感器、压频(V/F)转换器等硬件对缓冲材料在一定静压下的厚度变化量进行数据采集与分析,得出缓冲材料蠕变特性曲线。结果位移传感器采集缓冲材料随时间的位移形变,经信号调理、低通滤波后,输入给以LM331芯片所组成的V/F转换器,声卡采集该转换器所输出的频率信号并转换为数字信号,计算机读取该数字信号并在测试软件界面输出蠕变-时间、位移-时间、应力-时间等曲线。结论该测试装置和软件测试系统操作简单,使用PC自带声卡替代昂贵的数据采集卡作为数据采集系统,降低了成本,灵活性和可靠性较高,使缓冲材料的蠕变特性测试更加方便快捷,为更好地掌握缓冲材料蠕变特性进行缓冲设计提供了强有力的工具。     

Microstructure and creep properties of a cast intermetallic Ti–46Al–2W–0.5Si alloy for gas turbine applications

The microstructure and creep properties including minimum creep rate, time to 1% creep deformation and creep fracture time of a cast TiAl-based alloy with nominal chemical composition Ti–46Al–2W–0.5Si (at.%) were investigated. The creep specimens were prepared from investment-cast plate and two large turbine blades. Constant load creep tests were performed in air at applied stresses ranging from 150 to 400 MPa in the temperature range 973–1073 K. The microstructure of the specimens is characterised by optical, scanning and transmission electron microscopy before and after creep deformation. The minimum creep rate is found to depend strongly on the applied stress and temperature. The power law stress exponent of minimum creep rate is n = 7.3 and the apparent activation energy for creep is Q_a = 427 ± 14 kJ/mol. The initial microstructure of the creep specimen is unstable. The ₂(Ti₃Al)-phase transforms to γ(TiAl)-phase and needle-like B2-precipitates during long-term creep testing at all testing temperatures. At lower applied stresses, the creep specimens fail by the growth and coalescence of cavities and small cracks formed along the γ/₂ interfaces. At the highest applied stresses, the specimens fail by nucleation and propagation of cracks.