研削砥石の破壊に関する研究 (第2報)

AE法による破壊過程の解析

抄録

Previous work dealt with the effects of pores on macroscopic fracture of the vitrified grinding wheels. In the present work, fracture mechanisms of the same materials from the stages of microcrack growth to final fracture under uniaxial tensile loading are discussed by means of the acoustic emission monitoring which provides the information of dynamic morphological changes of them. Results of the emission monitoring revealed that a clear correlation between the crack growth behavior and the emission amplitude distributions was founded, and the incremental microcrack growth in the location of inhomogeniety could be detected throughout loading. It was also found with the specimens having sharp notches that, prior to the final fracture, intermittent fracture (break in two pieces) of abrasive grains or bondbridges or both took place, while with the specimens without notches that a simultaneous coalescence of each microcracks extended sufficiently to critical length should cause the final fracture. Although only qualitative discussion of the results were attempted in this study, the type of information obtained can readily be used for qualitative interpretation of the fracture mechanics of the materials.