ABSTRACT


Effect of epoxy adhesive on Joining Characteristics
of Dissimilar Al5052-CFRP

Park Jae-Woo
Advisor : Prof. Bang, Hee-Seon, Ph.D.
CO-Advisor : Prof. Bang, Han-Sur, Ph.D.
Department of Welding and Joining Science Engineering,
Graduate School of Chosun University


In recent years, regulations on automobile emissions and fuel consumption have been gradually strengthened. Vehicle weight reduction has become an essential element in the automotive industry. Hot stamping, hydro-forming and other methods are adopted to lighten the vehicle. However, it is difficult to meet the tightening regulations. Therefore, In this study, we are trying to satisfy the emission gas and fuel efficiency regulations of automobiles by using lightweight material, which is not a new method for lighter vehicles.

There are many materials such as super high tensile steel plate, non-ferrous material and carbon fiber reinforced plastic as lightweight materials, among which Al and CFRP were selected. There are many methods such as SPR and the like as the joining method between Al and CFRP, but FSJ is selected among them.
The purpose of this study is to improve the bonding between lightweight materials (CFRP and Al alloy) by using friction stir welding and epoxy adhesive. The materials used were CFRP (PA66) with a thickness of 1.5 mm and Al alloy (Al5052) with a thickness of 1.0 mm. The Al alloy was placed on top of the CFRP and overlapped. In order to increase the joint strength by causing interlocking phenomenon between materials, 5 surface roughness was given by Wet-Grinding to the bonding surface of Al alloy.

The process variables include tool rotation speed, plunge depth, and dwell time. Mechanical and metallurgical properties of the joints were evaluated by friction stir welding, adhesive bonding, and hybrid bonding. In this study, thermal distribution characteristics of Al/CFRP joints were investigated using numerical analysis program and compared with the experiment.

As a result, maximum tensile-shear strength in Friction Spot Joining was obtained approximately 3.3kN(400rpm, 0.3mm, 25s) and bonding with adopted adhesive was obtained approximately 6.4kN(400rpm, 0.2mm, 25s). Also, tensile shear strength in adhesive bonding was achieved approximately 6.1kN. The effect of bubble formed in the specimen and surface roughness is also considered in accordance with the results of tensile-shear strength.