Crack growth characterization in single-edge notched tension testing by means of direct current potential drop measurement. (September 2017)

• Record Type: Journal Article
• Authors: Van Minnebruggen, Koen; Hertelé, Stijn; Verstraete, Matthias A.; De Waele, Wim
• Is Part Of: International journal of pressure vessels and piping. Volume 156(2017)
• Page Start: 68
• Page End: 78
• Publication Date: 2017-09
• Subjects: SENT test -- Direct current potential drop -- Johnson -- Unloading compliance; Pressure vessels -- Periodicals; Pipe -- Periodicals; Récipients sous pression -- Périodiques; Tuyaux -- Périodiques; Pipe; Pressure vessels; Periodicals; 681.76041
• DOI: 10.1016/j.ijpvp.2017.06.009
• Languages: English
• ISSNs: 0308-0161

Abstract

Abstract: Single-edge notched tension (SENT) testing has gained attention for the characterization of crack growth resistance in scenarios of low crack tip constraint conditions. One challenge of SENT testing is the experimental characterization of crack extension during the test. Two common methods exist: unloading compliance and direct current potential drop (DCPD). Whereas the former method is fairly extensively described in existing procedures, applying the latter mostly depends on user experience and in-house developed analysis algorithms. This paper describes Ghent University's approach for DCPD measurements of ductile crack extension in SENT testing. A reference voltage drop measurement is advised, aiming to account for current leak and changes in electrical conductivity. Then, attention goes to the sensitivity of the procedure with respect to changes in crack size and its robustness with respect to probe positioning errors. Finally, DCPD is shown to have similar capabilities to unloading compliance with respect to defect sizing accuracy. The results of this paper are aimed to contribute to a more prescriptive description of DCPD measurements in revised SENT test procedures or standards. Highlights: A procedure is presented to measure crack growth in SENT testing by means of DCPD. A dual probe technique eliminates effects of current leak and temperature change. Positions for current pins and measurement probes are motivated. Crack growth is estimated with an accuracy similar to unloading compliance. Weld metal specimens have larger crack sizing errors than base metal specimens.