Technical progress summary for the period, March 1, 1992--January 1, 1993 Page: 1 of 9
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1. TECHNICAL PROGRESS SUMMARY
FOR THE PERIOD 3/1/92-1/1/93
During this period work has encompassed: a) development of electropotential drop
techniques to monitor the growth of cracks in steel specimens for a variety of specimen
geometries; b) micromechanical modeling of fracture using finite element calculations of
crack and notch-tip stress and strain fields; 3) examining helium effects on radiation
damage in austenitic and ferritic stainless steels; 4) analysis of the degradation of the
mechanical properties of austenitic stainless steels for the purpose of assessing the
feasibility of using these steels in ITER; 5) development of an integrated approach to
integrity assessment; and 6) development of advanced methods of measuring fracture
a. Potential Drop Techniques
The work on electropotential drop techniques is a continuation of efforts to develop a data
base from a variety of fracture specimen geometries to support the development of failure
criteria for thin-walled structures containing part-through surface cracks. We have
previously developed procedures for monitoring the evolution of cracks in miniaturized
compact tension (CT) geometries. During the last work period we helped develop that
capability at ORNL (with A. Rowcliffe and D. Alexander) in order to perform single-
miniaturized specimen fracture toughness tests on ferritic and austenitic steels irradiated
in HFIR. We have also continued to develop techniques for monitoring the growth of
part-through cracks. This work is being carried out by a PhD candidate Mat Enmark. An
experimental calibration between potential drop and crack size and shape has been
developed and successfully used to assess surface crack growth in HT-9. The potential
fields in a specimen containing a semi-elliptical crack have also been modeled using
finite element techniques. The agreement between finite element predictions and
empirical calibrations is excellent. Finally, the experimental and FEM studies are being
extended center crack panels. The wide array of specimen geometries (three-point
bend/compact tension, center-cracked panels, and surface-cracked panels), including a
variety of crack depth to specimen width variations, will provide a reliable basis to
predict failure conditions in complex fusion structures.
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Technical progress summary for the period, March 1, 1992--January 1, 1993, report, February 1, 1996; United States. (digital.library.unt.edu/ark:/67531/metadc668318/m1/1/: accessed December 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.