Elucidation of impact toughness controlling factor of dissimilar joints for multi-materials design of automobile

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K14822
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Composite materials/Surface and interface engineering
• Research Institution: Osaka University
• Principal Investigator: TAKASHIMA Yasuhito 大阪大学, 接合科学研究所, 助教 (50397692)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: 異材継手 / 動的負荷 / 断熱変形 / シャルピー衝撃特性

Outline of Final Research Achievements

In this work, dynamic temperature fields and strain energy distribution in a dissimilar steel joint was numerically analyzed by means of three-dimensional explicit finite element method. The temperature in the soft steel particularly increased during the dynamic loading. A high-speed infrared camera was used to measure the temperature field near the bonded interface. The numerically calculated temperature fields showed reasonable agreement with that measured. Furthermore, the influence of strength mismatch in dissimilar joints on the Charpy absorbed energy was evaluated on the basis of the Weibull stress criterion for brittle fracture. Charpy test results for a clad joint of dissimilar steels were characterized by the strength mismatch ratio.

Free Research Field

破壊力学・衝撃工学

Academic Significance and Societal Importance of the Research Achievements

自動車のマルチマテリアル化を進めるうえで異材接合部には十分な強度とともに耐衝撃性が求められることになるが，この研究によって得られた成果により，異材継手を構成する材料の強度差に応じて継手の破壊抵抗を評価可能な手法構築に至った。この手法を用いることで，強度の組合せに応じて継手の破壊抵抗を予測することが可能となり，強度と軽量性を兼ね備えるバランスの良い異材の組み合わせを導く指針につながるものと見込んでいる。