Session: MF-29-01 Mechanical Properties of Nuclear Graphite and their Implementation in Codes and Standards (Joint with CS-15)

Paper Number: 107838

107838 - Integration of Full Field Digital Image Correlation With Standard Disc Compression Test on Small Size Nuclear Graphite Samples 

The ASTM C749 “Standard Test Method for Tensile Stress-Strain of Carbon and Graphite” requires dog-bone shaped test specimens. Unfortunately, the specimen sizes required for ASTM C749 are not only too large for efficient irradiation within a material test reactor, but are also incompatible with available irradiation capsule volumes, molten salt degradation facilities, and oxidation testing apparatus. To resolve these incompatibilities, the ASTM D8289 “Standard Test Method for Tensile Strength Estimate by Disc Compression of Manufactured Graphite” was developed as an alternative method for smaller specimens when geometric constraints were present. However, the test results collected under ASTM D8289 are limited to estimates of the graphite’s tensile strength. Due to the difficulties of using traditional strain gauges or extensometers on such small specimens, the disc splitting test in ASTM D8289 cannot record the important stress-strain relation throughout the test loading history. To gather stress-strain data, a digital image correlation (DIC) method has been used that provides full-field, non-contact, surface displacement measurements. This method was applied along with the ASTM D8289 splitting tensile test on small graphite samples from graphite grades Mersen 2114 and IG-110 to track their deformation during compressive loading. Initial results showed that the DIC technique can measure the surface displacement/strain on these small (Ø6 × 3 mm) graphite specimens with high accuracy and good repeatability. It is expected that combining DIC techniques with small disc splitting tensile tests can provide the stress-strain evolution through the loading history yielding additional useful information when applying ASTM D8289. Further comparison of measured strains with analytical and numerical simulation results is expected to shed light on the mechanical behavior of these nuclear graphite materials in complex stress state.

Presenting Author: Lianshan Lin Oak Ridge National Laboratory

Presenting Author Biography: Dr. Lianshan Lin of Oak Ridge National Laboratory holds a Ph.D. degree in Mechanical Engineering from the Manchester University, and is currently a staff member of the Oak Ridge National Laboratory. Dr. Lin works in the areas of structural materials in nuclear engineering including high temperature alloys and graphite, with current research projects focusing on nuclear graphite mechanical properties characterization, digital image correlation (DIC) application in graphite tests, and the physical solid-fluid reaction between molten salt and graphite.

Authors:

Lianshan Lin Oak Ridge National Laboratory
Charles Hawkins Oak Ridge National Laboratory
Cristian Contescu Oak Ridge National Laboratory
James Spicer Johns Hopkins University
Jose Arregui-Mena Oak Ridge National Laboratory
Nidia Gallego Oak Ridge National Laboratory