Study on the Fatigue Strength of Dissimilar Adhesive Joints between Steel and Aluminum Alloy

Teppei Oe･Teppei Oe (Mazda)･Takahiro Suzuki (Toyota Auto Body)･Kouhei Yamamoto (Yamaha Motor)･Hiroaki Kawamura (Toyota Motor)･Takefumi Murai (Sunstar Engineering)･Hiroyuki Oguma (National Institute for Materials Science)･izuru Nishikawa (Osaka Institute of Technology)･Atsushi Sugeta (Hiroshima University)･Yoshihiko Uematsu (Gifu University)

The fatigue characteristics behavior of adhesively bonded dissimilar joints between steel plate and aluminum alloy plate was investigated, covering specimen fabrication, acquisition of fundamental data, and evaluation methodologies. Through these efforts, the influences of adherend stiffness and adhesive-edge geometry on the fatigue strength of dissimilar material joints were clarified. Furthermore, by introducing the stress intensity factor, a unified approach for evaluating fatigue strength was proposed.

Investigation of the Effects of Water Absorption and Post-Absorption Drying on Adhesive Strength

Takahiro Miyawaki (Mitsubishi motors)･Kazuo Hattori (AISIN)･Ryuuta Kubota (TOYOTA MOTOR KYUSHU)･Takaaki Inoue (SUNSTAR ENGINEERING)･Masaki Tani (TOYOTA INDUSTRIES)･Hiroyuki Oguma (National Institute for Materials Science)･Izuru Nishikawa (Osaka Institute of Technology)･Atsuhsi Sugeta (Hiroshima University Graduate School)･Yoshihiko Uematsu (Gifu University)

The degradation and control conditions of test specimens required to quantitatively evaluate the effects of adhesive layer thickness and post-absorption moisture content factors considered to influence the fatigue strength of adhesive joints have not yet been established. In this study, we examined specimen fabrication methods using lap shear specimens to quantitatively assess the impact of moisture-induced degradation on fatigue properties. Additionally, we investigated the effects of moisture absorption and subsequent drying on static strength.

Loosening phenomenon of a thin plate bolted joint subjected to bending moment

Shoma Osaka (Shibaura Institute of Technology, Graduate school)･Yutaro Kurabayashi･Shinji Hashimura (Shibaura Institute of Technology)

In our previous study, we have revealed that when a bending moment is applied to a thin plate bolted joint, the reduction of clamping force, that is loosening, occurs even if the bending moment has been released. We investigated effects of various tightening conditions of the thin plate bolted joint, such as the clamping force, plate thickness, and plate width, on loosening.

Influence of Temperature on the Friction of Contact Surface Treated in case of the Bolted Joints

Yukio Morozumi (Toyota Motor)･Yuuya Omiya･Hayate Shimoyama･Shotaro Terao (Kagawa University)

Bolt fastening is a joining technique that relies on frictional force. Since vehicles are sometimes exposed to high temperatures, understanding the friction characteristics at the contact surfaces under such conditions is considered important for ensuring reliability. In this study, a test equipment to measure friction coefficients was developed, and measurements were conducted on specimens with anti-corrosion surface treatment utilized to screw parts. Based on observations and characteristics of the contact surfaces, the influences of temperature are discussed.

Effects of Substrate Surface Roughness and Adhesive Elongation on the Adhesion Strength of Metal–Composite Joints

go yoshida･souichiro nishino (Ibaraki University)

With the progress of multi-material usage in structural components, adhesive bonding has gained attention as a joining technique for metal materials and polymer composites. In this study, the effects of substrate surface roughness and adhesive elongation on adhesion strength were investigated.

Strain-Life Fatigue Life Prediction of Arc Welded Joints Incorporating Detailed Weld Bead Notch Geometry Modeling in chassis parts

Dooyoung Kim･Jae Hong Park･Hyunki Kim (HMG(Hyundai Motor Group))･Wansoo Youk (Hwashin)･Fatemi Ali (Memphis University)

This study aims to improve the accuracy of fatigue life prediction for chassis components that include arc welds. The conventional S-N approach based on Equivalent Structural Stress (ESS) is highly versatile, but it has limitations in defining and accurately identifying stress concentration points (hot spots) at notches such as the toe and root of weld beads. To overcome these limitations, this study seeks to develop a modeling technique that can reflect the complex three-dimensional notch geometry of actual weld beads. Using the developed modeling technique, the applicability of the strain-life (ε-N) approach, which considers local plastic deformation, can be ensured, thereby providing a more reliable fatigue life prediction than existing methods. The predicted life is validated by comparison with fatigue test results of RR CTBA components.