脆性材料の衝撃曲げ試験に関する基礎的研究 : セメントモルタル試験体による場合

抄録

We have proposed the method of measuring the acceleration of the hammer as a standardized testing method of the impact bending strength of brittle materials. The specimen resists the impact load by the strength of the material and the body force of the specimen. The former is named "Impact Bending Strength (E_s)", the latter is "Inertia Resistance (F_I)" and sum of these is named "Impact Bending Toughness (P)". In this paper, the impact bending properties of cement-mortar specimen are examined. In § 4, the deformation of the specimen under impact bending load is investigated by the elastic analysis and some experiments. In § 5, the calculation method of the "Inertia Resistance (F_I)" is described. The method is based on the theory that substitute the deformation and movement of the specimen for the revolution movement of a reged body and the theoretical calculated results almost coincides with the experimental results in the experiments to determine whether the assumption used in this theory is good or not. "Inertia Resistance (F_I)" increase with the hammer's speed being faster and when the specimen shows localized bending defor-mation (E_I) is smaller than the (F_I) when the specimen deforms in the whole span. In § 6 and § 7, the values of (F_s) and (P) of the specimens are investigated by several impact bending test. It was clear that the specimen has least "Impact Bending Toughness (P)" when the hammer strikes the specimen at the speed that corresponds to the period of first normal mode of the specimen. "Impact Bending Strength (E_s)" decrease with the hammer's speed Vo being faster in the slower limits than the speed that corresponds to the period of first normal mode of the specimen, but (F_s) is constant in the higher speed than that.