外文翻譯--關于北歐的疲勞實驗室的比較—測量結果不確定值的反映

1、中文 中文 4060 字 出處： 出處：Accreditation and quality assurance, 2005, 10(5): 208-213附錄附錄 1英文原文Reflections regarding uncertainty of measurement, on the results of a Nordic fatigue test interlaboratory comparisonMagnus Holmgren,

2、 Thomas Svensson, Erland Johnson, Klas JohanssonAbstract This paper presents the experiences of calculation and reporting uncertainty of measurement in fatigue testing. Six Nordic laboratories performed fatigue tests on

3、steel specimens. The laboratories also reported their results concerning uncertainty of measurement and how they calculated it. The results show large differences in the way the uncertainties of measurement were calculat

4、ed and reported. No laboratory included the most significant uncertainty source, bending stress (due to misalignment of the testing machine, “incorrect” specimens and/or incorrectly mounted specimens), when calculating t

5、he uncertainty of measurement. Several laboratories did not calculate the uncertainty of measurement in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) [1].Keyword： Uncertainty of measurem

6、ent, Calculation, Report, Fatigue test, Laboratory intercomparisonDefinitions ：R Stress ratio Fmin/Fmax · F Force (nektons) · A and B Fatigue strength parameters · s and S Stress (megapascals) · N Num

7、ber of cycles. IntroductionThe correct or best method of calculating and reporting uncertainty of measurement in testing has been the subject of discussion for many years. The issue became even more relevant in connectio

8、n with the introduction of ISO standards, e.g. ISO17025 [2]. The discussion, as well as implementation of the uncertainty of measurement concept, has often been concentrated on which equation to use or on administrative

9、handling of the issue. There has been less interest in the technical problem and how to handle uncertainty of measurement in the actual experimental situation, and how to learn from the uncertainty of measurement calcula

10、tion when improving the experimental technique. One reason for this may be that the accreditation bodies have concentrated on the very existence of uncertainty of measurement calculations for an accredited test method, i

11、nstead of on whether the calculations are performed in a sound technical way. The present investigation emphasizes the need for a more technical focus.One testing area where it is difficult to do uncertainty of measureme

12、nt calculations is fatigue testing. However, there is guidance on how to perform such calculations, e.g. in Refs. [3, specimens were distributed to the participants by the organizer.ResultsThe primary laboratory results

13、that should be compared are the estimated Whaler curves. In order to present all results in the same way, the organizer transformed some of the results. The Whaler curves reported by the participants are shown in Fig. 1.

14、It can be seen that there are considerable differences between laboratories. An approximate statistical test shows a significant laboratory effect. Material scatter alone cannot explain the differences in the Whaler curv

15、es. In order to investigate if the laboratory effect was solely caused by the modeling uncertainty, we estimated new parameters from the raw data with a common algorithm. We then chose to use only the failed specimens an

16、d to make the minimization in the logarithmic life direction. The results are shown in Fig. 2. A formal statistical significance test was then made, and the result of such a test shows that the differences between the la

17、boratories shown in Fig. 1 could be attributed only to modeling.Uncertainty of measurement calculationsOne of the most important objectives with this investigation was to compare the observed differences between laborato

18、ry test results with their estimated uncertainties of measurement. The intention was to analyze the uncertainty analyses as such, and to compare them to the standard procedure recommended in the ISO guide: Guide to the E

19、xpression of Uncertainty in Measurement (GUM) [1].The laboratories identified different sources of uncertainty and treated them in different ways. These sources are the load measurement, the load control, the superimpose

20、d bending stresses because of misalignment and the dimensional measurements. Implicitly, laboratory temperature and humidity, specimen temperature and corrosion effects are also considered. In addition, the results show

21、a modeling effect. The different laboratory treatments of these sources are summarized in Table 1.Specific comments on the different laboratoriesAll laboratories gave their laboratory temperature and humidity, but did no

22、t consider these values as sources of uncertainty, i.e. the influence of temperature and humidity was neglected. This conclusion is reasonable for steel in the temperature range and humidity range in question [7].Laborat

23、ory 1. The uncertainty due to the applied stress was determined taking load cell and dimensional uncertainties into account. The mathematical evaluation was made in accordance with the GUM. Specimen temperature was measu

24、red, but was implicitly neglected. The modeling problem was mentioned, but not considered as an uncertainty source. Laboratory 2. The report contains no uncertainty evaluation. The uncertainties in the load cell and the