Chapter 22 Observation of Dynamic Deformation Behavior Around Interface of Bi-material Using DIC Yu Oishi, Shuichi Arikawa, Satoru Yoneyama, Hiroyuki Yamada, and Nagahisa Ogasawara Abstract In this study, the impact deformation behavior at the interface of a bi-material having different elastic wave velocities difference of each material is investigated. A split Hopkinson pressure bar method is used for the impact test. The deformation behavior of each material are observed using high-speed digital camera at the speed of one million frames per second and the strains distributions at the interface are measured using digital image correlation. The results are compared with the strains in a specimen without interface. The results show that the strain distribution in one material near the interface is affected by the strain in another material. The complicated deformation behavior is observed at the bi-material interface as the results of the interaction of elastic weaves in both materials. Keywords Digital image correlation • High-speed digital camera • Bi-material • Displacement distributions • Strain distributions 22.1 Introduction Recently, composite materials such as CFRP are used for transportation equipments, for example airplane or car, and small products, for example, golf club or tennis racket. Situations of using composite materials will increase because of the requirement of high strengthening and weight saving. Additionally, situations that the composite materials are used under impact loading increase. Therefore, it is necessary to investigate the dynamic mechanical characteristic of the composite materials. An investigation of residual strength after a impact loading has been performed [1]. Moreover, mechanical characteristics of CFRP under various dynamic conditions have been investigated [2–4]. The macroscopic behaviors of the composites have been studied, but each dynamic behavior of the fiber, matrix and its interface of the materials have not been investigated. The reason is that the observation of the elastic wave is difficult because this wave speed is very fast. In contrast, such micro scale observation has been performed in static deformation by digital image correlation [5–9]. When the impact load is applied to the bi-materials it is considered that the shearing impact deformation occurs at the interface according to the different wave speed of different materials. The investigation of the dynamic deformation mechanism around the interface is important. By using high-speed camera and digital image correlation, it is expected that the observation of dynamic deformation is possible. However it is difficult to observe the micro scale deformation under the impact load. Then it can be observed by the enlargement of the material. In this study, to investigate the dynamic deformation around the interface, a dynamic deformation behavior of a bi-material having different wave velocities is observed by digital image correlation using the high-speed camera. Accordingly, bi-material is prepared by bonding materials with different velocity of elastic wave. Then, materials having comparatively low elastic wave velocity are applied for the experiment to make observation easier. For the impact test, a Y. Oishi (*) • S. Arikawa • S. Yoneyama Department of Mechanical Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan e-mail: c5613113@aoyama.jp H. Yamada • N. Ogasawara Department of Mechanical Engineering, National Defense Academy of Japan, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686, Japan B. Song et al. (eds.), Dynamic Behavior of Materials, Volume 1: Proceedings of the 2014 Annual Conference on Experimental and Applied Mechanics, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-06995-1_22, #The Society for Experimental Mechanics, Inc. 2015 141
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