AE源となる孔を屈曲して配置した試験片のAE計測システム評価への適用性の検討

抄録

The applicability of the specimens with drop-like holes aligned to the polygonal line for generating intended acoustic emission (AE) signals to evaluate the performance of AE measurement systems was investigated. The stress distribution of the specimen subjected to a tensile load determined by finite element analysis demonstrates that high-stress areas appear along the line from the tip of the hole to the center of the arc of the next hole. This fact implies that cracks will generate in the direction toward the hole tip so that the location of the crack generation is enlarged by aligning such holes in two-dimension. It was found that intermittent crack generation is expected for the specimen with the holes having an angle of not small since the degree of stress concentration decreases monotonically in the order lined up, while multiple cracks might generate simultaneously for the small-angle due to a slight difference in the degree of stress concentration between some holes. The result of a tensile test shows that multiple load decreases appeared under loading, and generations of cracks between each hole were observed at the time of load decreases. A large number of AE counts with high amplitude were measured at the time of load decreases, and those sources were located around the tip of holes and the notch. Therefore, one can obtain AE signals caused by cracking at the intended location. Consequently, it was revealed that the specimens are suitable to evaluate the systems from the viewpoints of AE parameters and source location.