First direct measurements of transformation strains in crack-tip zone

Mahyar S. Dadkhah; David B. Marshall; Winfred L. Morris

doi:10.1117/12.49504

1 December 1991 First direct measurements of transformation strains in crack-tip zone

Mahyar S. Dadkhah, David B. Marshall, Winfred L. Morris

Proceedings Volume 1554, Second International Conference on Photomechanics and Speckle Metrology; (1991) https://doi.org/10.1117/12.49504
Event: San Diego, '91, 1991, San Diego, CA, United States

Abstract

Computer automated high-accuracy strain-field mapper (HASMAP) was used to measure strains responsible for crack tip shielding in partially stabilized zirconia containing 9% MgO (Mg-PSZ). HASMAP is used to determine the strain fields from the measured displacement fields by cross-correlation analysis of the relative positions of visible surface texture on the micrograph. The system is used to determine the relative displacement fields by comparing a pair of SEM or optical micrographs, one recorded before the load is applied (the reference micrograph) and the other afterwards. This system is capable of measuring both in-plane and out-of-plane displacements to accuracies approaching ± 60 A for optical microscopy, and ±10 A for scanning electron microscopy. Measured strains were used to evaluate the crack tip shielding stress intensity factor. Dilatational strain accounts for most, but not all, of toughening in Mg-PSZ.

Citation Download Citation

Mahyar S. Dadkhah, David B. Marshall, and Winfred L. Morris "First direct measurements of transformation strains in crack-tip zone", Proc. SPIE 1554, Second International Conference on Photomechanics and Speckle Metrology, (1 December 1991); https://doi.org/10.1117/12.49504

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