脆性材料を対象とした衝撃曲げ試験に関する研究 : 数値解析による検討(モルタル試験体)

Abstract

The purpose of this study is to establish the standardized testing method of the impact bending strength for brittle materials. We have proposed a testing method to measure the acceleration of the hammer. The basic properties of mortar specimens under impact bending load have been obtained by some experiments. In this paper, it was analytically clarified that the testing method in this study was reasonable to evaluate the impact bending strength of specimens. The behaviors of mortar specimens under impact bending load were calculated by FEM analysis that solved the two-dimensional wave equations. The acceleration curves measured in the experiments were used as input loadings for numerical analysis. The strains of the specimens calculated by FEM analysis coincided with the experimental results, so the acceleration of the hammer could be a value to express the magnitude of impact load to the specimen. Then it seemed that the mortar specimen cracked by tensile stress within the limits of the hammer velocity in this study because the calculated shearing stress of specimen was so small. The strain of specimen increased in proportion to the magnitude of impulse when the period of impact loading was shorter than the period of first normal mode of specimen. So it was reasonable to express the impact strength of the specimen by physical unit of impulse. In conclusion, it seems that the testing method and analytical method in this paper would be useful to evaluate the toughness of brittle materials under impulsive bending load.