We equipped a composite wing structure fiber Bragg grating (FBG) arrays including 246 FBGs with 10 mm gauge
length, eight and six long-length FBGs with 300 mm and 500 mm, respectively. The length of the wing was 6 m and it
was made of carbon fiber reinforced plastics (CFRP). The sensing system based on optical frequency domain
reflectometry (OFDR) was used in a series of load tests. The measured results by FBG arrays showed the overall
deformation of the wing and good agreement with analysis results. Additionally, strain distributions of stress
concentration zones were successfully measured by long-length FBGs.
The objective of this study is to clarify the fracture mechanism of unidirectional CFRP (Carbon Fiber Reinforced Plastics) under static tensile loading. The advantages of CFRP are higher specific stiffness and strength than the metal material. The use of CFRP is increasing in not only the aerospace and rapid transit railway industries but also the sports, leisure and automotive industries. The tensile fracture mechanism of unidirectional CFRP has not been experimentally made clear because the fracture speed of unidirectional CFRP is quite high.
We selected the intermediate modulus and high strength unidirectional CFRP laminate which is a typical material used in the aerospace field. The fracture process under static tensile loading was captured by a conventional high-speed camera and a new type High-Speed Video Camera HPV-1. It was found that the duration of fracture is 200 microseconds or less, then images taken by a conventional camera doesn't have enough temporal-resolution. On the other hand, results obtained by HPV-1 have higher quality where the fracture process can be clearly observed.
This paper examines damage monitoring for woven graphite/epoxy laminate by means of an electrical resistance change method. The method has been proposed by the authors and successfully applied to cross-ply and quasi-isotropic laminates; the method has yet to be applied to woven laminates. Therefore, a woven graphite/epoxy composite is selected for the target material of the electrical resistance change method to identify the damage. Beam type specimens consisting of woven laminates are the focus of this paper. The influence of a different electrical property of woven laminate upon the electrical resistance change is investigated both analytically and experimentally, and the condition of the electrical contact between the electrode and the specimen is investigated experimentally. For the purpose of identification, the response surface is adopted as a solving method for the inverse problem. As a result, the method shows excellent performance for estimating delamination locations and sizes.