実物試験片による光ファイバの破壊靱性の評価

概要

論文の詳細を見る
The fracture toughness of optical glass fibers, the dimension of which is very small in diameter, has been evaluated directly. The method and results are summarized as follows. A silica glass fiber 125 μm in diameter without a silicone resin coating was indented with a Vickers diamond pyramid. A pre-crack was then introduced by pulling the indented fiber specimen in a longitudinal direction. Each pre-cracked fiber specimen was tested under constant tensile loads in atmospheric air. After the delayed fracture of the fiber specimen occurred, the fracture surface was observed in order to see the crack shape at the onset of the final unstable fracture. Next, based on the observed crack front, the stress intensity factor K_I at the onset of the final unstable fracture, i.e., fracture toughness K_<IC> was evaluated by the 3-D boundary element method. The fracture toughness K_<IC> of optical glass fibers was 0.77Mpa√m, which was slightly smaller than that obtained from the indirect evaluation using a WOL-type CT specimen.
一般社団法人日本機械学会の論文
1989-04-25