Abstract
In order to assure the reliability of acoustic emission (AE) method, standardization using specimens that generate the intended AE is expected. Since different shaped holes in the specimen cause the different magnitude of stress concentration, a set of holes having different shapes could be used to occur intended fracture. In this study, the influence of the difference in hole shape on stress concentration was examined by the finite element method. From a discussion based on the comparison between the determined stress distribution of the specimen with rhombic holes and drop-like holes, it was found that cracks generate intermittently in the specimen in the case that the difference in the stress concentration factor between each end of the hole is large such as the drop-like hole. It was also found that changing the opening angle of holes and the distance between holes could change the value of the stress concentration factor and fan-like holes are more useful to align a lot of holes. A tensile test was conducted for a specimen with fan-like holes made by stereolithography to confirm the validity of the proposed concept. It was demonstrated that cracks generate intermittently and AE events corresponding to each crack growth could be measured. So that, it was concluded that specimens with multiple fan-like holes are suitable for standardization of AE measurement.
