Skip to main content
SHARE
Publication

Effects of graphite porosity and anisotropy on measurements of elastic modulus using laser untrasonics...

Publication Type
Conference Paper
Book Title
Procceedings of IEEE International 2014 Ultrasonics Symposium
Publication Date
Volume
N/A
Publisher Location
Chicago, Illinois, United States of America
Conference Name
2014 IEEE International Ultrasonics Symposium
Conference Location
Chicago, Illinois, United States of America
Conference Date
-

Laser ultrasonic techniques can be used to study the ultrasonic properties of nuclear graphites and can serve as tools in establishing relationships between materials microstructure and the macroscopic stiffnesses of graphite. Establishing structure-property relationships permits improved ultrasonic sensing of graphite microstructural changes related to service-induced degradation. Laser ultrasonic measurements were made using a pulsed Nd:YAG laser source and detection was performed using a Michelson-type interferometer. This source-receiver combination provides for non-contacting, highly linear transduction of broadbanded, ultrasonic pulses permitting simultaneous determination of longitudinal and shear stiffnesses. Measurements show that among the graphites examined, a change in density of 0.26 g/cm3 (average 1.8 g/cm3) results in a change in the longitudinal elastic stiffness of 9.2 GPa (average 11.3 GPa) and 3.2 GPa (average 4.3 GPa) for the shear stiffness. Larger variations in density were produced by controlled oxidation of IG-110 and NBG-18. Shear wave birefringence measurements using laser line sources in IG-110 and PCEA indicate that IG-110 behaves isotropically while PCEA displays texture characteristic of transversely isotropic materials.