プラスチックの破壊じん性試験のための予き裂導入法に関する研究
Precracking Techniques for the Fracture Toughness Tests of Plastics
Zhenlin Pang・栗山 卓・成澤郁夫
Pang, Zhenlin / Kuriyama, Takashi / Narisawa, Ikuo
The technique of introducing an initial crack in specimens for Kc and Gc tests has a significant effect on their values. This study is concerned with the technique of sliding a razor blade a method which is recommended in the ASTM Standard protocol. A new equipment for machining a saw slit and subsequently sliding a razor blade at the bottom of the slit has been made and the machining and sliding conditions which introduce a residual stress-free crack have been investigated. The polarized observations revealed that the most stress-fee crack tip could be obtained by machining using a U-shaped blade at low rotational speeds while moving the specimen at high speeds. The slow sliding of a razor blade is also preferable to reduce the residual stress at the crack tip.
Key words: Fracture toughness / Sliding / Precracking / Tapping / Slitting