Theory and application of laser ultrasonic shear wave birefringence measurements to the determination of microstructure orientation in transversely isotropic, polycrystalline graphite materials

摘要: Abstract Laser ultrasonic line source methods have been used to study elastic anisotropy in nuclear graphites by measuring shear wave birefringence. Depending on the manufacturing processes during production, can exhibit various degrees of material related preferred crystallite orientation and microcracking. In this study, laser measurements birefringence NBG-25 performed assess anisotropy. sources allow specific polarizations for waves be transmitted – corresponding wavespeeds compute bulk, moduli that serve quantify These modulus values interpreted using physical property models based distribution coefficients microcrack-modified, single crystal represent combined effects microcracking Ultrasonic results are compared contrasted with coefficient thermal expansion show relationship from these techniques.