Delamination detection in fiber metal laminates using the mode conversion of Lamb waves

Yoji Okabe, Hibiki Hirakawa, Hayato Nakatani, Shinji Ogihara

Research output: Contribution to conferencePaperpeer-review

1 Citation (Scopus)

Abstract

Fiber metal laminates (FMLs) consisting of FRP composites and thin metal foils are gathering attention as structural materials for aircrafts. However, it is difficult to apply the conventional ultrasonic method to detect the inside damages because of the total reflection at the first interface between the FRP and the metal. Recently, the authors have developed a new delamination detection method based on the mode conversion of Lamb waves. In this research, therefore, this method was applied to detect the inner delamination in the FML. MFC actuators and FBG sensors were bonded to both top and bottom surfaces of the laminate in order to excite or receive only A modes or S modes separately. The laminates with an artificial delamination were manufactured by embedment of Teflon films in the middle of the thickness, and Lamb waves were propagated through the delaminated area. The results indicated that excited A1 mode was converted into S0 mode in the delaminated area and it returned to A1 mode again after passing through the delamination. Since the velocity dispersion is clearly different between the two modes, the delamination length could be estimated quantitatively from the change in the dispersion of received A1 mode.

Original languageEnglish
Pages2212-2219
Number of pages8
Publication statusPublished - 2014
Event7th European Workshop on Structural Health Monitoring, EWSHM 2014 - Nantes, France
Duration: 8 Jul 201411 Jul 2014

Conference

Conference7th European Workshop on Structural Health Monitoring, EWSHM 2014
Country/TerritoryFrance
CityNantes
Period8/07/1411/07/14

Keywords

  • Delamination
  • Fiber metal laminates
  • Lamb wave
  • Mode conversion

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