Prof. Takahiro Ohashi
Head of Mechanical Engineering Department, Kokushikan University, Japan
Biography: Prof. Takahiro Ohashi is Head of Mechanical Engineering Department at Kokushikan University. Prof. Takahiro Ohashi is one of the representative delegate of Japan Society for Technology of Plasticity from April 2016 to now. Also, he is the board of trustees of Aluminum Forging Association in Japan. Prof. Takahiro Ohashi experienced in directing a national research project for a new die structure of Ministry of Economy, Trading and Industry (METI), as well as experienced in directing 3 research teams of National Institute of Advanced Industrial Science and Technology (AIST). Meanwhile, Prof. Takahiro Ohashi gained the Best Paper Award in ICAMEM2016 at April 2016, and won the Second Paper Award in ICMEA2016 at September.
Speech Title: Proposal of "Easily-Decomposable Dissimilar-Materials-Joining" Concept with Friction Stir Forming
Abstract: Recently, joining dissimilar materials, including steel, CFRP, and aluminum alloy, has been successfully studied due to multiple materials used in the structure of automobiles. The material ratio of normal steel in a car exceeds 60% now; however the U.S. government predicts that it will fall into less 20% in next 20 years. However, it is natural to imagine that such multiple-material products will be a problem for recycling in future. Joining the materials more tightly and wholly makes it more difficult to separate them in the recycling procedure. Therefore, it is worthwhile to discuss methods for easily decomposable joined dissimilar materials. This presentation provides a framework of the "easily-decomposable dissimilar-materials-joining" with friction stir forming approaches. Friction-stir forming (FSF) is a friction-stir process invented by Nishihara in 2002. In FSF, a material is put on a die, and friction stirring is then conducted on its back surface. The material deforms and precisely fills the cavity of the die due to high pressure and heat caused by friction stirring. Materials in the process often display outstanding deformability and moldability. In the presentation, the authors will suggest utilizing the process for the fabrication of a hook-like mechanical joint that can be separated simply by sliding the joined materials each other. Additional opposite hooks generated by the above approach or additional location pins prevent joined members from sliding, and the hooks join them tightly. In recycling, the materials can be separated smoothly by sliding materials each other after cutting them between the hooks, or destroying / removing the location pins. The above separating procedure can be made more complicated for safety with adding more opposite hooks in various direction or more location pins. The presentation also provides some examples of "easily-decomposable dissimilar-materials-joint" and evaluations of their strength.