کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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775069 | 1463761 | 2015 | 9 صفحه PDF | دانلود رایگان |
This work presents a novel methodology for characterising fatigue cracks under biaxial conditions on a low carbon steel. It allows both short crack and early propagation stages to be studied in tubular specimens. Short crack growth is studied with a long-distance microscope acquiring images of the bare metal surface. Results showed oscillations in crack growth rate due to microstructure. Early propagation stage is studied with high magnification Digital Image Correlation (DIC) technique for measuring displacement and strain crack-tip fields. By applying micro-speckle pattern on the metal surface it is possible to achieve high magnification for DIC technique. Ultra-fine black and white speckles were created by electro-spray technique. The validity of this novel technique is demonstrated by direct comparison with extensometer measurements, under combined tension–compression and torsion conditions. It was also possible to estimate satisfactorily the mixed-mode stress intensity factor.
Journal: International Journal of Fatigue - Volume 71, February 2015, Pages 17–25