科研之友
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摘要
Fry method is a graphical technique that displays the strain ellipse in the form of central vacancy on a point distribution, the Fry plot. For objective strain estimation from the Fry plot, the central vacancy must appear as a sharply focused ellipse. In practice, however, a diffused appearance of the central vacancy in the Fry plots induces considerable subjectivity in direct strain estimation. Several alternative computer based methods have recently been proposed for objective strain estimation from the Fry plots. Relative merits and limitations of these methods are, however, not yet well understood. This study compares the accuracy and efficacy of the six recent methods proposed for objective strain estimation from the Fry plot. The six methods are based on four different approaches, the point density contrast, the image analysis, the Delaunay triangulation and the point distribution analysis. We test and compare these methods by: (i) generating variously sorted object sets through computer simulations, (ii) distorting the object sets, with the help of computer graphics software, by pure shear, simple shear and simultaneous pure-and-simple shear and, (iii) estimating the errors. Results from more than 2900 tests imply that the continuous function method and the Delaunay triangulation method yield most accurate strain estimates. The image analysis method gives very accurate principal strain orientations but overestimates the strain ratio, specially, in strongly distorted object sets. The point distribution analysis methods are successful mostly on those point distributions that are obtained by pure shear distortion of well-sorted objects with specific boundary conditions. With respect to the time-efficiency, the image analysis method and the Delaunay triangulation method are found to be most rapid.
- 出版日期2014-6
