| 摘要 |
PURPOSE: To evaluate damage on a metal sample, e.g. the blade of gas turbine, because of creep and the residual service life accurately. CONSTITUTION: A metal sample is irradiated with ultrasonic wave and the energy of backscattering wave between the surface and the bottom face is determined as the total sum of energy of respective frequency components. The ratio P/P0 is then determined by normalizing with the energy P0 at the initial stage of creep and the damage is evaluated based on the phenomenon that the ratio increases as the damage because of creep increases. Similarly, creep damage and residual service life are evaluated based on the phenomenon that the central frequency fc of the energy of backscattering wave decreases as the damage because of creep decreases. |
