Coating Thickness Characterization of Composite Materials Using Terahertz Waves

Recently, terahertz ray imaging has emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques for the area applications. In this study, a new time-domain spectroscopy system was utilized for measuring the coating thickness on CFRP composite laminates. Extensive experimental measurements in reflection mode were made to map out the T-ray images. Also, the refractive index was estimated based on the electromagnetic properties. The CFRP composite laminates were observed in reflection mode and limitations will be discussed in the T-ray processing. By using these characterized material properties, the characteristics was successfully demonstrated for T-ray behavior propagating through the Shim Stock films for acquiring the refractive index. The T-ray technique has been developed for the measurement of the thickness of the Shim Stock films and the coating thickness on CFRP composites. Good results have been obtained in tests made on the thickness of the standard film samples with the coating thickness ranging from around hundreds of μm.

Terahertz Ray Imaging: A New Ray of Hope in Imaging Science

Imaging technology is becoming increasingly prevalent in our society.Even though there were many successful imaging modalities ever since the advent of roentgen rays, they all have their shortcomings. And imaging of dental tissue had always been a challenge in imaging science due to the various layers which differ in physical and chemical and structural properties. Considerable improvisations of existing techniques and new research activities.

T-Ray NDE Inspections on the Fiber Direction of Thermoplastic PPS-Based CFRP Composites

Terahertz ray (T-ray) imaging has been emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques, and new application systems are under processing development for the area applications. The terahertz time domain spectroscopy (THz TDS) can be considered as a useful tool using general non-conducting materials; however it is quite limited to conducting materials. In this study, a new time-domain spectroscopy system was utilized for detecting and evaluating layup effect and flaw in FRP composite laminates. In order to solve various material properties, the index of refraction (n) and the absorption coefficient (α) are derived in reflective and transmission configuration using the terahertz time domain spectroscopy. However, the T-ray is limited in order to penetrate a conducting material to some degree. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS (poly-phenylene sulfide)-based CFRP solid laminate.

Terahertz Ray Nondestructive Characterizations in FRP Composites

Recently, terahertz ray imaging has emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques, and new application systems are under processing development for the area applications. In this study, a new time-domain spectroscopy system was utilized for detecting and evaluating layup effect and flaw in FRP composite laminates. Extensive experimental measurements in reflection mode were made to map out the T-ray images. Especially in this characterization procedure, we estimated the electromagnetic properties such as the refractive index. Estimates of properties are in good agreement with known data. Furthermore layup effect and flaw of FRP composite laminates were observed in reflection mode and limitations will be discussed in the T-ray processing.