高速高压低温温度传感器的试验研究

简要介绍了高速高压低温条件下温度传感器的试验研究方法。试验研究的着重点是尽量利用现有的设备、试验条件和有关的氢氧发动机研制过程中的试验，对传感器进行一些针对性试验，以取得可靠的试验数据。通过对试验数据的分析和研究，验证考核传感器的性能。主要给出了强度试验、动态特性试验和恢复系数试验的模拟试验方案和方法及搭载试验方法，给出了某传感器进行上述试验的试验结果，结果表明，这种试验研究方法是可行且可靠的。     

导弹模型的靶道试验技术研究

本文针对弹道靶道试验的基本特点,在分析研究导弹模型在无控飞行条件下的运动特征和试验测试方法的基础上,系统研究了导弹模型的靶道试验原理和方法、试验模型发射技术、导弹试验模型设计、试验数据处理方法等,最后进行了试验方法的验证试验.试验结果证明,采用本文所述的试验技术在弹道靶道中进行导弹模型的自由飞行试验是切实可行的.     

GB/T 228.1-2010中金属材料拉伸试验速率控制方法的分析

通过两组拉伸试验分析了不同试验阶段及试验数据特性、试验过程的速率控制方法及其对试验数据的影响,研究了位移速率控制方法在试验过程中的控制状态,为相关试验人员合理选择试验速率控制方式提供参考。     

在干热环境条件下汽车主要户外大气暴露试验方法分析

本文首先对户外大气暴露试验的意义进行分析,对汽车主要的户外大气暴露试验方法进行分类和概述,分别阐述了汽车零部件的黑箱试验、太阳跟踪聚光暴露试验、IP／DP箱试验以及整车的暴露试验,并对其试验场地、试验准备以及试验方法进行探讨。     

基于虚拟试验的冲击磨损可靠性强化试验研究

为缩短可靠性试验周期、降低试验成本,结合虚拟试验技术对系统进行可靠性强化试验研究。以机械系统磨损失效为研究对象,通过磨损试验理论分析确定了磨损强化试验机理,提出了虚拟强化试验技术确定原则,推导了接触磨损强化系数,并利用MATLAB软件编制了相应的计算程序。基于炮闩系统虚拟样机,对平面接触的冲击磨损零部件进行了具体的强化试验,制定了强化试验技术方案,试验结果表明所采用的强化试验技术可行,研究成果有助于促进虚拟试验在可靠性强化试验领域的应用。     

讲座：仪器仪表的可靠性（完）——第四讲 仪器仪表的可靠性试验与可靠性评定

可靠性试验是指为评价、分析产品可靠性而进行的试验，而可靠性评定则是根据可靠性试验或仪器仪表运行使用中得到的数据，利用概率统计的方法，推断出产品的可靠性指标，可靠性试验的种类习惯上可以分为环境试验、寿命试验、筛选试验、鉴定试验以及可靠性增长试验等。     

力控振动试验与过试验现象分析

传统的卫星加速度控制试验是根据特定的加速度规范,测量并控制振动台台面的加速度,由这种试验方法做出的估计往往过于保守,会在试件结构的固有频率处产生过试验现象,对结构造成过响应的危害.力控试验是测量并控制卫星结构与振动台台面之间的界面力,这种试验方法能够有效地改善由加速度控制试验造成的过试验现象.本文在传统加速度控制试验产生过试验的原因和力控试验方法的过试验补偿原理的分析的基础上,进一步提出了双控试验这一方法,即同时测量并控制界面力与台面加速度,并且可以更好地模拟真实发射过程中的卫星结构的动力学环境.本文通过数值仿真算例,验证了力控试验对过试验现象具有明显的改善效果,以及双控试验是最为理想的卫星动力学环境试验方法.为力控和双控试验方法真正应用于我国卫星动力学振动试验提供了理论依据.     

实时耦联动力试验方法理论与实践

实时耦联动力试验是将物理试验与数值计算实时耦联的一种结构动力试验方法。这一试验方法兼具了常规振动台试验与拟动力试验的优点,被认为是结构动力试验方法发展的趋势之一,成为当前结构抗震试验研究的热点。该文首先阐述了实时耦联动力试验方法的基本原理以及关键问题,并综述了实时耦联动力试验研究的发展现状;然后介绍了清华大学水工振动研究组在实时耦联试验方面的研究实践;最后提出了实时耦联动力试验亟待突破的研究问题。     

离子推力器寿命试验总结与展望

在充分调研国内外成熟度较高的离子推力器产品地面寿命试验的基础上,总结了关键失效磨损试验、工程型号寿命试验、产品极限寿命试验和综合评价寿命试验等四类离子推力器寿命试验的目的、方法、结果及应用.通过不同寿命试验方法之间、试验验证寿命与工程应用寿命之间、不同失效模式及其试验验证方法之间的对比分析,总结了各类寿命试验的成功经验...     

智能机器人全自动冲击试验系统在夏比摆锤冲击试验中的应用

全自动冲击试验机由于结构设计的原因,在进行夏比摆锤冲击试验时,测量设备状态及试验的人工冲击操作等降低了试验效率和结果准确率。介绍了智能机器人全自动冲击试验系统的构造、试验概述和优势,将自动冲击与人工冲击进行了对比分析。结果表明:智能机器人全自动冲击试验系统按照夏比摆锤冲击试验标准设定,冲击试验时间恒定,保证了试验节奏的一致性,得到的试验结果偏差小且数据分布更为集中,减少了人为误差和试验结果的波动性,降低了试验结果的误判和错判的概率,提高了试验效率和结果准确率。     

Beurteilung des Haftvermögens von PVD-Hartstoffschichten mittels tribologischer Kurzzeit-Tests

Assessment of the Adhesion of PVD-Coatings by Means of Tribological Short-Time Tests As a result of an increasing use of wear resistant coatings in tribological applications, the evaluation of adhesion by means of a simple, fast and reproductial test method becomes more and more important. Although various standard adhesion tests already exist, the transferability of these results to real applications is often insufficient. To assess the adhesion of different PVD-coatings tribological short-time tests were carried out under sliding friction conditions. The testing parameters were chosen in such a way, that on the one hand information concerning adhesion of the coating were shortly obtainable, but on the other hand the coatings were not worn out to early. Finally the results of the tribological short-time tests were compared with that of real cutting tests. The results of the tribological short-time tests show a very good qualitative correlation with cutting tests. TiN- and (Ti, Al)N-coatings which demonstrate inadequate adhesion in short-time tests, fail during cuttings tests very shortly. This is also value for coatings with a good adhesion, which do well in tribological short-time tests as well as in real cutting tests. Therefore the tribological short-time tests may be an interesting method for evaluating adhesion of PVD-coatings in a fast and cheap way.     

Residual strength of reinforced concrete columns exposed to fire

Abstract

Several methods were employed to evaluate the residual strength of reinforced concrete columns exposed to different durations of fire. These methods included the analytical method, ultrasonic tests, hammer tests and load tests. Fifty columns were involved in the tests. Calculated temperatures and residual strengths of the test columns were compared with those measured. Comparisons were also made between results from load tests and those from nondestructive tests. The results showed that using analytical procedures is acceptable while the nondestructive test methods are accurate only for shorter durations of fire.     

Constitutive relationship of polyolefin fibre–reinforced concrete: Experimental and numerical approaches to tensile and flexural behaviour

Flexural tensile tests are usually used to evaluate the suitability of fibre‐reinforced concrete (FRC) in structural applications. The constitutive relationships of FRC are derived from such tests by using several inverse analyses. Given that the structural design of FRC is based on the residual load‐bearing capacities obtained under flexural tests, the approach to analyse fracture behaviour by means of uniaxial tensile tests would mean use of more direct and reliable constitutive curves compared with those obtained by indirect means. The significance of this paper lies in the characterisation of polyolefin fibre–reinforced concrete (PFRC) not only by using fracture flexural results tests but also by comparing such results with the direct tensile behaviour of the material obtained from uniaxial tests. This comparison would both extend the knowledge of the PFRC mechanical properties and broaden the reliability of structural design by comparing the behaviour of PFRC under flexural and tensile stresses. Moreover, the suitability of an iterative method proposed by the authors for obtaining the constitutive relations of PFRC from flexural tests has been checked by performing a series of numerical simulations of the tensile tests performed. The differences in the properties obtained in the flexural tests and the tensile tests have been assessed. The experimental results gathered from the tensile tests have been accurately reproduced by using a cohesive crack approach with trilinear softening functions by the iterative inverse analysis proposed.     

Impact on HDPE and PVC plates – Experimental tests and numerical simulations

This paper presents first material tests on HDPE and PVC, and subsequently impact tests on plates made of the same materials. Finally, numerical simulations of the plate impact tests are compared with the experimental results. A rather comprehensive series of mechanical material tests were performed to disclose the behaviour of PVC and HDPE in tension and compression. Quasi-static tests were carried out at three rates in compression and two in tension. Digital image correlation, DIC, was used to measure the in-plane strains, revealing true stress–strain curves and allowing to analyze strain-rate sensitivity and isotropy of Poisson's ratio. In addition, dynamic compression tests were carried out in a split-Hopkinson pressure bar. Quasi-static and dynamic tests were also performed on clamped plates made of the same PVC and HDPE materials, using an optical technique to measure the full-field out-of-plane deformations. These tests, together with the material data, were used for comparative purposes of a finite element analysis. A reasonable agreement between experimental and numerical results was achieved.     

Bonding strength test method assessment for Cross-Laminated Timber Derived Stressed-Skin Panels (CLT SSP)

Different methods, including bending tests and small and medium size shear tests, were used to assess the skin to stringer glue line shear strength of Radiata Pine Cross-Laminated Timber Derived Stressed-Skin Panels (CLT SSP). Bending test shear strengths were estimated using the mechanically jointed beam theory (gamma method) for Cross-Laminated Timber (CLT) panels with modifications in the layers’ effective widths, and then compared with results from the small and medium size shear tests. Small and medium size shear tests proved to be possible methods for assessing bonding strength for factory production control. The small shear tests provided lower strength values and higher scatter results than those gathered from the medium size tests. The mean shear strength results obtained from bending tests were inferior to the values obtained from the small and medium size specimens. The bending tests proved necessary for assessing the mechanical behaviour of CLT SSP.     

Effect of test frequency on fatigue strength of low carbon steel

Ultrasonic fatigue tests (test frequency: 20 kHz) and conventional tension–compression fatigue tests (10 Hz) have been conducted on annealed and 10% pre-strained specimens of 0.13% carbon steel. Small holes were introduced on the specimen surface to investigate the effect of test frequency on small crack growth. The dynamic stress concentration factor and the stress intensity factor under ultrasonic fatigue tests were checked to be almost the same as those of conventional tension–compression fatigue tests. However, the fatigue properties were dependent on the test frequency. Ultrasonic fatigue tests showed longer fatigue life and lower fatigue crack growth rate for the annealed and 10% pre-strained specimens. Slip bands were scarce in the neighbourhood of cracks under ultrasonic fatigue tests, while many slip bands were observed in a wide area around the crack under conventional fatigue tests. In order to explain the effect of test frequency on fatigue strength, dynamic compression tests with Split Hopkinson bars were carried out. The stress level increases substantially with the strain rate. Thus, the increase in fatigue strength might be, to a large extent, due to a reduction in crack tip cyclic plasticity during ultrasonic fatigue tests.     

Fracture characteristics of three metals subjected to various strains,strain rates,temperatures and pressures

This paper considers fracture characteristics of OFHC copper, Armco iron and 4340 steel. The materials are subjected to torsion tests over a range of strain rates, Hopkinson bar tests over a range of temperatures, and quasi-static tensile tests with various notch geometries. A cumulative-damage fracture model is introduced which expresses the strain to fracture as a function of the strain rate, temperature and pressure. The model is evaluated by comparing computed results with cylinder impact tests and biaxial (torsion-tension) tests.     

Small punch testing and its numerical simulations under constant deflection force conditions

A comparison of results of small punch tests on miniaturized discs under a constant force with their simulation by means of FEM is presented. A heat-resistant steel of type CSN 41 5313 (EN 10CrMo9-10) was selected for our investigations. The small punch tests as well as the necessary conventional creep tests on massive specimens were performed at 873 K. For simulations, the Norton power-law and the exponential relationships were applied in the FEM model of the SPT arrangement. Parameters of both relationships were derived from stress dependences of minimum creep rate obtained from the conventional creep tests. While at higher loads the Norton power-law yields results more comparable with those obtained from experiments, at lower loads the exponential relationship gives better results. The investigation also confirms the simple relation between stress in conventional tests and force in small punch tests resulting in identical time to fracture of both types of tests. __________ Translated from Problemy Prochnosti, No. 1, pp. 32–35, January–February, 2008.     

Identification of process and distribution characteristics by testing monotonic and non-monotonic trends in failure intensities and hazard rates

Statistical tests are developed for testing monotonic and non-monotonic trends in failure data. A procedure is presented, by using a set of six tests as an example, to determine whether a failure process is a renewal process, a homogeneous or a non-homogeneous Poisson process, or none of these. The same tests with different data transformations can also be used for testing the goodness of fit of candidate hazard rates (i.e. distributions) and failure intensities. Several examples illustrate the potential power of these tests and the importance of testing for non-monotonic as well as monotonic trends. The efficiency of these tests is discussed in several special cases.     

Bedeutung von Prüfmethoden für die Auslegung verschleißbeanspruchter Bauteile

Test Methods and Dimensioning of Tribologically Loaded Parts Owing to the complexity of tribological systems the testing of wear components is of particular significance. Here is an effort to show the advantages and disadvantages of product tests, component tests and model tests. Even with model tests good results for the products are attainable when relevant parameters are systematically varied. Hereto some examples are given.