The behavior of the crack tip region under in-plane fracture toughness testing was observed by means of CCD camera with enlarging lens system, and was quantitatively analyzed as "crack opening". From the relationship between "crack opening" and displacement, the start point of the crack propagation can be clearly determined. It varies with specimen direction and size. Smaller specimens tend to start at the maximum load point, while larger specimens start earlier. Generally, the start point of MD specimens are not so far from the maximum load point as in the case of CD specimens. Specimens with smaller ligament length were confirmed to satisfy the prerequisite of "Essential Work of Fracture" method to obtain the fracture toughness of paper.
|Journal||Nihon Hoso Gakkaishi|
|Publication status||Published - 1997|
|MoE publication type||A1 Journal article-refereed|
- fracture toughness
- crack propagation
- CCD camera
- infrared thermography