Abstract
This study deals with a non-destructive evaluation technique for detecting defects in composite panels. In this non-destructive evaluation technique, various low-frequency techniques are applied such as a tapping technology. Another terahertz wave application will be utilized. In particular, the tapping technique is utilized in order to evaluate the characteristics of the honeycomb member based on the hysteresis effect analysis. Here, the area surrounded by the hysteresis loop in the force-displacement curve is related to the increased internal friction loss that is the cause of the energy absorption absorbed by the composite member after the load is applied. The loop area where the composite member was damaged was well agreed with the damage level. Artificial defects were manufactured on the surface of honeycomb sandwich composite panels. An NDE technique was proposed in order to detect defects by using terahertz waves and was discussed for tuning the practical use.
Highlights
Composite materials have the advantage of high specific strength and stiffness over compared to metals, but are brittle to impact damages
The resultant internal damage can produce a hysteresis loop in the load-displacement response of the impact site. This approach shows the stiffness reduction and the mechanical hysteresis caused by impact damage in composites and strives to develop nondestructive inspection methods based on these changes
3.1 Impact damages By using time domain spectroscopy (TDS) T-ray waves, the several delaminations in GFRP solid composite laminates were imaged based on the reflection mode from on the power described above
Summary
Composite materials have the advantage of high specific strength and stiffness over compared to metals, but are brittle to impact damages. The purshed system is used to produce images of both the impact duration of the taps and the deduced spring constant that shows the local stiffness of the structure [4,5,6]. The resultant internal damage can produce a hysteresis loop in the load-displacement response of the impact site This approach shows the stiffness reduction and the mechanical hysteresis caused by impact damage in composites and strives to develop nondestructive inspection methods based on these changes. The use of T-rays as an NDE tool for detecting and characterizing flaws and impact damage in GFRP solid composites will be investigated compared with the results of tapping testing
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