Mid-infrared pulsed laser ultrasonic testing for carbon fiber reinforced plastics

Masahiro Kusano; Hideki Hatano; Makoto Watanabe; Shunji Takekawa; Hisashi Yamawaki; Kanae Oguchi; Manabu Enoki

doi:10.1016/j.ultras.2017.11.015

Mid-infrared pulsed laser ultrasonic testing for carbon fiber reinforced plastics

Ultrasonics. 2018 Mar:84:310-318. doi: 10.1016/j.ultras.2017.11.015. Epub 2017 Nov 24.

Authors

Masahiro Kusano¹, Hideki Hatano², Makoto Watanabe³, Shunji Takekawa², Hisashi Yamawaki⁴, Kanae Oguchi⁵, Manabu Enoki⁵

Affiliations

¹ Research Center of Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan. Electronic address: KUSANO.Masahiro@nims.go.jp.
² Research Center for Functional Materials, National Institute for Materials Science, 1-1, Namiki, Tsukuba, Ibaraki 305-0044, Japan.
³ Research Center of Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan; Research Center for Advanced Science and Technology, The University of Tokyo, The University of Tokyo, 4-6-1, Komaba, Meguro, Tokyo 153-8904, Japan.
⁴ Research Center of Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
⁵ Department of Materials Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-0033, Japan.

PMID: 29197737
DOI: 10.1016/j.ultras.2017.11.015

Abstract

Laser ultrasonic testing (LUT) can realize contactless and instantaneous non-destructive testing, but its signal-to-noise ratio must be improved in order to measure carbon fiber reinforced plastics (CFRPs). We have developed a mid-infrared (mid-IR) laser source optimal for generating ultrasonic waves in CFRPs by using a wavelength conversion device based on an optical parametric oscillator. This paper reports a comparison of the ultrasonic generation behavior between the mid-IR laser and the Nd:YAG laser. The mid-IR laser generated a significantly larger ultrasonic amplitude in CFRP laminates than a conventional Nd:YAG laser. In addition, our study revealed that the surface epoxy matrix of CFRPs plays an important role in laser ultrasonic generation.

Keywords: Carbon fiber reinforced plastics; Laser ultrasonic testing; Mid-IR laser; Wavelength conversion.