外文翻譯--關(guān)于北歐的疲勞實(shí)驗(yàn)室的比較—測(cè)量結(jié)果不確定值的反映（英文）

1、Accred Qual Assur (2005) 10:208–213 DOI 10.1007/s00769-005-0910-x P R A C T I T I O N E R S R E P O R TMagnus Holmgren Thomas Svensson Erland Johnson Klas JohanssonReflections regarding uncertainty of measurement, on the

2、 results of a Nordic fatigue test interlaboratory comparisonReceived: 20 October 2003 Accepted: 20 August 2004 Published online: 21 April 2005 ? Springer-Verlag 2005M. Holmgren ()) · E. Johnson · K. Johansson S

3、P Swedish National Testing and Research Institute, Box 857, 501 15 Bor?s, Sweden e-mail: magnus.holmgren@sp.se Tel.: +46-33-165007 Fax: +46-33-165010T. Svensson Fraunhofer-Chalmers Research Centre for Industrial Mathemat

4、ics, Box 857, 501 15 Bor?s, SwedenAbstract This paper presents the experiences of calculation and re- porting uncertainty of measurement in fatigue testing. Six Nordic labora- tories performed fatigue tests on steel spec

5、imens. The laboratories also re- ported their results concerning un- certainty of measurement and how they calculated it. The results show large differences in the way the un- certainties of measurement were cal- culated

6、 and reported. No laboratory included the most significant uncer- tainty source, bending stress (due to misalignment of the testing machine, “incorrect” specimens and/or incor- rectly mounted specimens), whencalculating

7、the uncertainty of mea- surement. Several laboratories did not calculate the uncertainty of measure- ment in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) [1].Keywords Uncertainty of mea

8、surement · Calculation · Report · Fatigue test · Laboratory intercomparisonDefinitions R Stress ratio Fmin/Fmax · F Force (newtons) · A and B Fatigue strength parameters · s and S Stres

9、s (megapascals) · N Number of cyclesIntroductionThe correct or best method of calculating and reporting uncertainty of measurement in testing has been the sub- ject of discussion for many years. The issue became eve

10、n more relevant in connection with the introduction of ISO standards, e.g. ISO17025 [2]. The discussion, as well as implementation of the uncertainty of measurement con- cept, has often been concentrated on which equatio

11、n to use or on administrative handling of the issue. There has been less interest in the technical problem and how to handle uncertainty of measurement in the actual experi- mental situation, and how to learn from the un

12、certainty of measurement calculation when improving the experi- mental technique. One reason for this may be that the accreditation bodies have concentrated on the very exis- tence of uncertainty of measurement calculati

13、ons for an accredited test method, instead of on whether the calcu- lations are performed in a sound technical way. Thepresent investigation emphasises the need for a more technical focus.One testing area where it is dif

14、ficult to do uncertaintyof measurement calculations is fatigue testing. However, there is guidance on how to perform such calculations, e.g. in Refs. [3, 4]. To investigate how uncertainty of measurement calculations are

15、 performed for fatigue tests in real life, UTMIS (the Swedish fatigue network) started an interlaboratory comparison where one of the most essential parts was to calculate and report the uncertainty of measurement of a t

16、ypical fatigue test that could have been ordered by a customer of the participating labora- tories. For cost reasons, customers often ask for a limited number of test specimens but, at the same time, they re- quest a lot

17、 of information about a large portion of the possible stress-life area [from few cycles (high stresses) to millions of cycles (low stresses) and even run-outs]. The way the calculation was made should also be reported. T

18、he outcome concerning the uncertainty of measurement from the project is reported in this article.210glected. The modelling problem was mentioned, but not considered as an uncertainty source. Laboratory 2. The report con

19、tains no uncertainty evaluation. The uncertainties in the load cell and the micrometer are considered, but neglected with refer- ence to the large material scatter. Specimen tempera- ture was measured. Modelling problems

20、 are mentioned by a comment regarding the choice of load levels. Laboratory 3. The report contains no uncertainty evaluation. However, the accuracy of the machine is given and the load was controlled during the tests to

21、be within specified limits. The bending stresses were measured on one specimen, but their influence on the fatigue result was not taken into consideration. Laboratory 4. The uncertainties in the load cell and the dimensi

22、onal measurements are considered in an eval- uation of stress uncertainty. The method for the eval- uation is not in accordance with the GUM method, but was performed by adding absolute errors. The bending stress influen

23、ce and the control system deviations are considered, but not included in the uncertainty evalu- ation. The failure criterion is mentioned and regarded as negligible, and corrosion is mentioned as a possible source of unc

24、ertainty. Laboratory 5. Uncertainties in the load cell and the load control were considered, and the laboratory stated in the report that the evaluation of the load uncertainty was performed according to the CIPM method.

25、Laboratory 6. No report was provided, but only ex- perimental results and a W?hler curve estimate.No laboratory reported the uncertainty in the estimated material properties, the W?hler parameters, but at most the uncert

26、ainty in the applied stress. The overall picture of the uncertainty considerations is that only uncertainty sources that are possible to estimate from calibration re- ports were taken into account in the final evaluation

27、.One important source that several laboratories men-tioned is the bending stresses induced by misalignment in the testing machine, incorrectly mounted test specimens or “incorrect” specimens. The amount of bending stress

28、 was also estimated in some cases, but its influence on the uncertainty in the final W?hler curve was not investi- gated.The results from this experimental investigation showthat there are different ways of determining t

29、he W?hler curve from the experimental result. One problem is the surviving specimens, the run-out results. Four laboratories used only the failed specimens’ results for the curve-fit, one laboratory neglected all results

30、 at the lowest level, and one laboratory included the run-outs in the estima- tion. Another problem is the mathematical procedure for estimating the curve. Common practice, and the recom- mendation in the ASTM standard,