汽车空调环境模拟试验室设计及特点

本文阐述了汽车空调系统环境模拟试验室设计及特点，结合国内外汽车空调环境模拟试验室的技术资料分析，提出了汽车空调性能模拟试验技术的发展趋势。     

高速公路水泥比对试验分析

通过试验室的水泥对比试验进行试验室内和试验室间的一致性实际统计值K的分析，客观反映试验过程的影响因素，针对参加奉次比对试验的试验室提出改进。     

马瑞利动力系统公司中国技术中心的空调设计

阐述了各种发动机性能试验室的设计工况和工艺要求,介绍了相应的空调、通风和水系统的系统设计。     

风冷式冷藏柜试验室的设计

本文叙述了冷藏柜试验室的设计要求及所采用的空调设计和计算机自动控制检测系统的设计。该试验室投资省,运行费用低、测量精度高、调试方便。     

人工环境试验室内空气流场的研究

采用数值模拟方法对人工环境试验室内的送风腔腔体结构进行模拟计算，结合实际情况分析试验室现有送风结构的特点，对试验区域的空气流场进行详细的分析，对工程设计选型与空调检测试验具有实用参考价值。     

强制对流空气冷却器性能试验室设计研究

本文对近年来在渔获物保鲜，食品冻结加工及低温保藏过程中，使用越来越广泛的强制对流翅片管空气冷却器的试验室设计作了研究。考虑到这类空气冷却器里空气的流动和传热过程都是很复杂的，有一系列的特点，而且空气冷却器结构形式多样，使用条件又各异，不可能用理论推导的数学关系来概括全部因素和过程，所以本文选择了建立性能测试试验室的方法来研究上述问题。我们根据国内这类空气冷却器使用的特点，参照国外标准方法，采用了夹套试验室方案。试验内容包括：评定空气冷却器产冷量；测定传热系数；翅片排管空气侧阻力降；制冷剂侧阻力降等。试验室最低温度可达到－３５℃，能满足国内蒸发面积２５－４００平方米的各型空气冷却器的性能试验。从已进行的多次空气冷却器性能检测表明试验室能较好满足使用要求。文中还介绍了试验室主要测试仪表的要求，参照资料［６］，［９］可知，如果能满足文中所提测试仪表的要求，可望把制冷量测定的误差控制在±１０％以内。     

大型风冷冷水机组工况试验室声学设计

以实际工程为例,介绍了在大型风冷冷水机组性能试验室中如何进行试验室声学设计,在满足大型风冷机组性能试验的基础上,在兼顾工况试验所需要的温度变化、湿度变化以及气流组织需要的同时,考虑噪声测试的特殊需要,采取合理组织气流走向等技术措施,保证大型空调冷冻设备性能试验室内的声场效果达到预期要求。     

机车及柴油机噪声测试试验室研究

在声学试验室进行机车部件及柴油机噪声测试试验和研究,规划设计噪声测试试验室整体布局及相关技术参数。     

数字试验室技术在建设工程检测行业应用的研究

本文分析了数字试验室技术在国际上的发展阶段,并结合目前国内试验室管理水平及计算机软硬件技术的现状,提出了数字试验室在国内的几大研究方向,并结合数字试验室的具体功能特点,阐述了这一技术对试验检测行业的促进作用并展望了其在国内的发展前景。     

浅谈新风系统在环境风洞试验室中的应用

在环境风洞试验室中,新风系统是净化试验舱内空气,补充新鲜干燥的空气以及维持试验舱内湿度稳定的必要系统。该文主要介绍了在某环境风洞试验室中新风系统的设计和应用,着重从该新风系统的除湿原理、主要工作部件、工作过程以及控制系统等方面进行阐述。     

Application of the reference stress method for interpreting impression creep test data

Impression creep tests have been performed on a 316-stainless steel at 600°C, for which conventional uniaxial creep test data are available. It is shown that the technique, based on the reference stress approach, for converting impression creep test data to equivalent uniaxial creep data, is accurate. The results show that the impression creep technique can be used for obtaining creep properties for materials which have high creep resistance at high temperature and test pressure conditions. The difficulties and limitations associated with such situations are described and methods of dealing with them are outlined.     

Long-term creep strength predictions from short-term creep test data for high Cr creep-resistant steels and microstructural evolution origin of over-predictions

A new tensile creep model that integrates the tensile strength at creep temperature is investigated for its generic applicability in predicting the long-term creep strengths from short-term creep test data for high Cr creep-resistant steels using creep and tensile strength data measured for a grade of 11Cr steel. The results show that, when the long-term creep strengths are specified by stresses producing the required minimum creep rate, they can be accurately predicted using short-term creep test data. However, when they are specified by stresses giving the required creep rupture time, using only short-term creep test data will lead to over-predictions. The microstructure evolution origin of such over-predictions is traced to the Z-phase precipitation during creep in creep-resistant steels with more than 9 wt.% Cr. The conventional concept on the relationship between creep test stress and creep mechanisms is also re-evaluated in light of the new results.     

High temperature test rig for inert atmosphere miniature specimen creep testing

A creep test rig is described which allows to perform creep experiments with miniature tensile creep specimens under an inert gas atmosphere at temperatures up to 1150°C. Previous work on the development of a miniature tensile creep test procedure is described. The key elements of the new inert gas system are then described. The test rig yields reliable creep data. Three examples for applications of the new system addressing grain boundary sliding in a TiAl alloy, creep cavitation and damage accumulation in copper and to provide high temperature creep data for a Co‐Re‐Cr alloy are given.     

Improved prediction model for time-dependent deformations of concrete: Part 4—Temperature effects

This Part presents a refinement of the BP model for the effects of temperature on the basic creep and drying creep of concrete. The temperature effect on basic creep is introduced through two different activation energies, one for the effect of temperature increase on the rate of hydration, which causes a decrease of creep, and one for the effect of temperature increase on the rate of creep, which causes an increase of creep. The dichotomy of these two opposing temperature influences is an essential feature, required for good agreement with test data. The greatest error in basic creep is again caused by the prediction of the material parameters from concrete composition and strength. This error can be largely eliminated by conducting limited short-time basic creep tests at different temperatures. Comparisons with 13 different data sets from the literature show a satisfactory agreement, better than that achieved with previous models, while at the same time the scope of the present model is broader. The effect of temperature on the creep of drying specimens is rather different because heating causes a moisture loss from unsealed specimens. The paper presents prediction formulae which modify those for drying creep at room temperature on the basis of the activation energy concept and take into account the effect of heating on the moisture loss. Comparisons with the limited test data that exist show satisfactory agreement. No additional material parameters depending on concrete composition and strength are introduced for drying creep.     

Long-term Creep Behavior of austenitic steel S-590 (X 40 CoCrNi 20 20)

Typical data from discontinuous long-term stress rupture tests were adapted for a differentiated creep analysis. A test series of more than 2000 000 h (23 years) single test time was available for austenitic steel S-590. This alloy was formerly used for high temperature applications. Various factors influence the creep behavior and cause anomalies from classical three-stage creep division. These phenomena are: microstructural instability, early creep damage (cavitation, microcracks) and corrosion. Typical features of diffusion creep were not observed. The procedure used in this examination and the principal findings can be applied to other high temperature materials.     

火灾下平行钢丝束温度膨胀及高温蠕变试验研究

采用非接触式应变视频测量系统,对常用于实际工程的1670级平行钢丝束进行了15个温度水平下的温度膨胀试验以及多应力水平下的高温蠕变试验,并对历经2 h高温蠕变试验后冷却至室温的平行钢丝束试件进行了抗拉强度测试,获取了平行钢丝束热膨胀应变历程及高温蠕变应变历程曲线。试验结果表明:平行钢丝束热膨胀应变随着温度升高呈非线性增长,且在750 ℃附近材料微结构发生相变;温度和应力水平对高温蠕变历程均会产生显著影响;蠕变试验温度愈高,应力水平对历经高温后平行钢丝束的剩余抗拉强度的影响愈显著;与1860级预应力钢绞线相比,1670级平行钢丝束具有较小的高温蠕变应变。基于试验数据,建议了平行钢丝束热膨胀系数关于温度的函数式及高温蠕变模型。该文所建议的平行钢丝束热膨胀系数及高温蠕变模型有利于预应力钢结构火灾高温下的力学响应分析。     

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.     

An assessment of three creep–fatigue life prediction methods for nickel‐based superalloy GH4049

High‐temperature low‐cycle fatigue tests with and without a 10‐s strain hold period in a cycle were performed on a nickel base superalloy GH4049 under a fully reversed axial total strain control mode. Three creep–fatigue life prediction methods are chosen to analyse the experimental data. These methods are the linear damage summation method (LDS), the strain range partitioning method (SRP) and the strain energy partitioning method (SEP). Their ability to predict creep‐fatigue lives of GH4049 at 700, 800 and 850 °C has been evaluated. It is found that the SEP method shows an advantage over the SRP method for all the tests under consideration. At 850 °C, the LDS and SEP methods give a more satisfactory prediction for creep–fatigue lives. At the temperatures of 700 and 800 °C, the SRP and SEP methods can correlate the life data better than the LDS method. In addition, the differences in predictive ability of these methods have also been analysed. The scanning electron microscopy (SEM) examination of fracture surfaces reveals that under creep–fatigue test conditions crack initiation mode is transgranular, while crack propagation mode is either intergranular plus transgranular or entirely intergranular, dependent on test temperature.     

基于VB、Excel和Access的蠕变实验机测控软件系统

数据采集和控制软件系统采用串口通协议,实现了对4台蠕变实验机多点数据采集和数据的自动记录。遵循温度控制器的RS485通讯协议,软件系统可以自动调控蠕变高温炉的温度。通过OLE技术和人工代码,VB与Access、Excel无缝连接,将试验数据保存到Access数据库中。运行结果表明系统的软、硬件工作稳定,可靠性高,完全实现了蠕变实验机的温度自动控制和试验数据的自动记录。     

Creep characterization of a type 316 austenitic steel

Creep data on a type 316 austeni tic steel are presented covering the temperature range 550-675°C and in volving test times up to 30 000 h. The data have been used to inv estigate the efficiency of traditional and recent methods of presenting creep data , the formulation of creep constit utive equations, and the valid ity of certain parametric relationships designed to aid extrapolation. Th e article introduces a form of the steel which will subsequently appear in a study of multi-axial stress/creep relationships and the development of a design method for creep conditions.