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| Estimation of Measurement Uncertainty for Principal Strains in Plane Field |
| Received:May 01, 2017 Revised:October 15, 2017 |
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| DOI：10.7643/issn.1672-9242.2017.10.018 |
| KeyWord:principal strain measurement of uncertainty second order LPU approach strain rosette strain state theory |
| Author | Institution |
| ZHU Xue-wang |
Institute of Systems Engineering, CAEP, Mianyang , China |
| ZHANG Si-jian |
Institute of Systems Engineering, CAEP, Mianyang , China |
| LIU Qing-lin |
Institute of Systems Engineering, CAEP, Mianyang , China |
| NONG Shao-ning |
Institute of Systems Engineering, CAEP, Mianyang , China |
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| Abstract: |
| Objective To assess the measurement uncertainties of principal strain in plane field. Methods A measurement model of nonlinearity transmission was established for the principle strain. The Law of Propagation of Uncertainty (LPU) approach based on second order Taylor expansion was applied to analyze the measurement uncertainty of the principle strain. The measurement models were established for two typical strain rosettes with the principle strain as the output, the values measured in the three directions of the strain rosettes as the input and the LPU was applied to the models. Numerical examples were designed to illuminate the procedures and methods of assessment and to compare with the first order LPU estimations. Results When strain rosette strain measurements were close in three directions, uncertainty estimation results of the principal strain obtained through this method and the method of first-order LPU had obvious difference. That of the principal strain was greater than that of the strain rosette in numerical value. When strain rosette strain measurements differ in three directions, the results obtained through this method and the first-order LPU method has little difference. Conclusion In special circumstances, the uncertainty value of principal strain is higher than those in any direction of rosette and different from the first order evaluations by one time. |
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