TY - JOUR
T1 - Real-time measurement of shear fatigue crack propagation at high-temperature using the potential drop technique
AU - Spitas, V.
AU - Spitas, C.
AU - Michelis, P.
N1 - Funding Information:
The research was partially sponsored by the European Commission within the 5th Framework Programme (G5RD CT-2002-00819).
PY - 2008/5
Y1 - 2008/5
N2 - In this paper, a direct method for real-time measurement of the advancement closed cracks propagating in Mode II (in-plane shear) is presented. The method is based on a modified potential drop technique applied on a patented shear specimen, the geometry of which ensures that under certain loading conditions a uniform shear field is developed in its central region (gauge area). Therefore, by continuously measuring the change in the electrical resistance (potential drop) between the two electrodes attached on the specimen it is possible to correlate this change with the progression of the crack within the specimen and in turn correlate the crack length with the stress intensity factor at the crack tip. This information can be used to create dα/dN - ΔKII plots as the experiment is progressing on-line from the acquired electrical data. The electrical field and the stress intensity factor in Mode II (KII) have been calculated for the shear specimen using finite element analysis (FEA) for various crack lengths and graphs indicating the change in crack length versus the change of the resistance of the specimen have been plotted. The method has been calibrated with optical measurements using a long distance observation microscope and it can be used in high-temperature testing of electrically conductive materials (i.e. nickel-based superalloys).
AB - In this paper, a direct method for real-time measurement of the advancement closed cracks propagating in Mode II (in-plane shear) is presented. The method is based on a modified potential drop technique applied on a patented shear specimen, the geometry of which ensures that under certain loading conditions a uniform shear field is developed in its central region (gauge area). Therefore, by continuously measuring the change in the electrical resistance (potential drop) between the two electrodes attached on the specimen it is possible to correlate this change with the progression of the crack within the specimen and in turn correlate the crack length with the stress intensity factor at the crack tip. This information can be used to create dα/dN - ΔKII plots as the experiment is progressing on-line from the acquired electrical data. The electrical field and the stress intensity factor in Mode II (KII) have been calculated for the shear specimen using finite element analysis (FEA) for various crack lengths and graphs indicating the change in crack length versus the change of the resistance of the specimen have been plotted. The method has been calibrated with optical measurements using a long distance observation microscope and it can be used in high-temperature testing of electrically conductive materials (i.e. nickel-based superalloys).
KW - Mode II cracks
KW - Potential drop method
KW - Real-time measurement
KW - Shear machine
UR - http://www.scopus.com/inward/record.url?scp=40949114613&partnerID=8YFLogxK
U2 - 10.1016/j.measurement.2007.01.003
DO - 10.1016/j.measurement.2007.01.003
M3 - Article
AN - SCOPUS:40949114613
SN - 0263-2241
VL - 41
SP - 424
EP - 432
JO - Measurement: Journal of the International Measurement Confederation
JF - Measurement: Journal of the International Measurement Confederation
IS - 4
ER -