微粒等方性黒鉛の破壊靱性に及ぼす切欠き先端形状の影響
Effect of notch-tip geometry on the fracture toughness of fine-grained isotropic graphite
松島 友貴*; 山田 輝明*; 黒田 雅利*; 角田 淳弥 ; 柴田 大受 ; 沢 和弘
Matsushima, Yuki*; Yamada, Teruaki*; Kuroda, Masatoshi*; Sumita, Junya; Shibata, Taiju; Sawa, Kazuhiro
微粒等方性黒鉛(ETU-10)の破壊靱性に及ぼす切欠き先端形状の影響を明らかにするため、切欠き先端角度が約15及び約30の2種類の試験片を用いて、三点曲げ破壊靱性試験を実施した。線形破壊力学に基づき、荷重-変位曲線上の最大荷重を用いて計算した破壊靱性値は、切欠き先端角度が約15と約30の試験片について、それぞれ0.933(MPa m), 0.926(MPa m)となった。両者の破壊靱性値がほぼ等しい値を示したことから、破壊靱性値は切欠き先端角度の影響を受けないことがわかった。また、破壊靱性値に及ぼす切欠き先端角度や曲率半径の影響を有限要素法解析により評価したシミュレーション結果と実験結果の比較結果についても議論する。
In order to investigate the effect of notch-tip geometry on the fracture toughness of fine-grained isotropic graphite ETU-10, three-point-bending fracture toughness tests have been performed by using two types of single-edge notched beam specimens with different notch angles of approximately 15 and 30. The values of the fracture toughness were calculated based on linear elastic fracture mechanics by using the maximum force which could be obtained by the load-displacement curve. As a result, the values of the fracture toughness of the specimens with the notch angles of approximately 15 and 30 were 0.933 MPa mand 0.926 MPa m, respectively. This suggested that the values of the fracture toughness were not affected between the notch angles. Further work has been ongoing to discuss the effect of the notch-tip geometry such as angle and root radius of notch in terms of finite element analysis.