Terahertz radiation NDE of composite materials for wind turbine applications

  • Je-Woong Park
  • Kwang-Hee Im
  • In-Young Yang
  • Sun-Kyu Kim
  • Sung-Jun Kang
  • Young-Tae Cho
  • Jong-An Jung
  • David Kuei Hsu
Article

Abstract

Nondestructive testing technique using T-ray (terahertz ray) has received more interest as a new capability tool in engineering application. So, T-ray time-domain spectroscopy was used for inspecting and evaluating physical property and defect characteristics in FRP composite materials for a use of wind energy. First of all, a general refraction mode and transmission mode was utilized for calculating a refractive index (n) based on the well-machined sample. In order to obtain the terahertz ray refractive index, a refractive mode and a transmission mode technique was defined for solving a refractive coefficient (n), with which refractive index of GFRP composites, balsa and epoxy for a use of wind turbine blades could be obtained. A method of wind turbine blade composites having one and two saw-cuts delaminations and some angles/directions was suggested based on the E-field vector. The time of flight in T-ray using evaluating a T-ray transmission mode agreed with that using T-ray time-domain spectroscopy with the wind turbine blade. Also, in CFRP composites, T-ray propagation is limited because the carbon fibers are blocking the T-ray. Therefore, we have analyzed difference between E-field vector in T-ray and the carbon fiber direction. Also, it was found that a T-ray time domain data in thick GFRP composite laminates seemed to show peaks with a regular spacing (Δt) which was obvious with the close relation between TOF and FFT.

Keywords

Wind energy Terahertz radiation NDE Composites 

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Copyright information

© Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Je-Woong Park
    • 1
  • Kwang-Hee Im
    • 2
  • In-Young Yang
    • 3
  • Sun-Kyu Kim
    • 4
  • Sung-Jun Kang
    • 4
  • Young-Tae Cho
    • 5
  • Jong-An Jung
    • 6
  • David Kuei Hsu
    • 7
  1. 1.Department of Naval Architecture and Ocean EngineeringChosun UniversityGwangjuSouth Korea
  2. 2.Department of Automotive EngineeringWoosuk UniversityJeonbukSouth Korea
  3. 3.Department of Mechanical Design EngineeringChosun UniversityGwangjuSouth Korea
  4. 4.Division of Mech. System EngineeringChonbuk National UniversityJeonju, JeonbukSouth Korea
  5. 5.Department of Manufacturing Design EngineeringJeonju UniversityJeonjuSouth Korea
  6. 6.Department of Mechanical and Auto. EngineeringSongwon UniversityKwangjuSouth Korea
  7. 7.Center for Nondestructive EvaluationIowa State UniversityAmesUSA

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