Development of new dynamic elastic constant estimation method for FRP and its validation using FDTD method

Speaker:
SAITOH, Takahiro; Gunma University; Japan

Authors:
Saitoh, T.; Gunma University; Japan
Ooashi, K.; Gunma University; Japan
Nakahata, K.; Ehime University; Japan

ID: ECNDT-0539-2018
Download: PDF
Session: Materials Characterization UT
Room: G1
Date: 2018-06-13
Time: 15:40 - 16:00

FRP (Fiber Reinforced Plastic) is known as one of the anisotropic materials and has been used as a member of aircraft, civil and architectural structures. The anisotropic property sometimes makes it difficult for inspectors to detect flaws in FRP because the phase and group velocities of the ultrasonic waves in anisotropic materials depend on their propagation directions. These velocities of the ultrasonic waves in a material can be determined by using the dynamic elastic constants of it. Therefore, it is important task to determine the dynamic elastic constants of the anisotropic material such as FRP.

In this research, a new dynamic elastic constant estimation method using the laser ultrasonic visualization testing is developed for FRP. The laser ultrasonic visualization technique is incorporated to measure the ultrasonic wave velocities which are required for elastic constant estimation. First, the procedure of our developed elastic constant estimation method is described with the anisotropic elastodynamic theory. An image processing technique for the visualized data obtained by the laser ultrasonic visualization testing is utilized to determine the phase and group velocities of the ultrasonic waves. Next, the FDTD (Finite Difference Time Domain) formulation used in this research is discussed. As numerical examples, the elastic constants of an FRP specimen are estimated by our proposed method. In addition, the simulation of ultrasonic wave propagation in the FRP with the estimated elastic constants is implemented by using the FDTD method previously discussed, and the results are compared with those obtained by the laser ultrasonic visualization testing to validate our proposed method.