近赤外線放射光を用いた全視野計測法の提案とSUS304製薄板引張試験片に生じる特異な変形挙動の観察への応用

抄録

In a tensile test by using a thin sheet specimen made of SUS304, the propagation of X-shaped region with strain localization has been observed in a later stage of deformation. Some researchers have considered this behavior is caused by strengthening the region because of strain-induced martensitic transformation (SIMT). The deformation behavior of SUS304 can be observed easily by full-field measurement methods such as the DIC and ESPI by tracking speckle correlation patterns, however, pre-processings with some complicated techniques are required. In this study, a new full-field measurement method based on near-infrared radiation to the specimen from one direction is proposed. The anomalous deformation behavior is observed by using the proposed method during the tensile test of SUS304. As a result, irregularly-reflected infrared ray from the surface of the specimen is captured as a random pattern. For a comparison, the tensile tests of A5052 and SS400 are also carried out to observe the Portvin Le-Chatlier and Luder’s bands. At the same time, the anomalous deformation behavior can be directly observed by applying simple post-processing of the images without establishing speckle patterns as pre-processing.