Influence of terahertz waves on the penetration in thick FRP composite materials

Kwang-Hee Im¹, David K. Hsu², Chien-Ping Chiou², Daniel J. Barnard², In-Young Yang³ and Je-Woong Park⁴


Abstract

Fiber reinforced plastics (FRP) are increasingly utilized in engineering structures because of their performance and fabrication advantages. With this increased utilization, a technique to gage quality and further characterize the materials would be beneficial. The nondestructive applications for Terahertz (T-ray) methods have also experienced increased utilization for evaluating engineering materials and will be reported on here in applications for the inspectionand characterization of FRP materials used in wind energy components. First, refraction and transmission T-ray modes are used to determine the refractive index (n) of a glass fiber reinforced plastic (GFRP) reference sample, and extended for calculating the refractive indicesfor a sample of GFRP, balsa and epoxy. Additionally, carbon fiber reinforced plastic (CFRP) samples were evaluated with respect to fiber directions versus T-ray electric field polarization direction to evaluate the level of penetration of T-ray energy due to the fiber orientation dependent conductivity of this composite material. Finally, an evaluation of T-ray data was made to evaluate resonance effects, where the resonance frequency was found to agree with that expected from reflections from individual plies in thick GFRP laminates.

This study was performed using TeraView's CW Spectra 400 system. (TeraView, Cambridge, UK)

Full Article: http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4865010