Effects of Surface Treatment for Mg Alloy and Hot-Melt Adhesive Film on Bending Properties of CFRTP and Mg Alloy Multi-Material Hat-Shaped Member

Abstract

In case of multi-material hat-shaped members, the bonding strength between dissimilar materials has a great influence on the bending stiffness of the entire structural member, thus it is an important issue to secure the bonding strength between dissimilar materials. In this study, in order to develop a multi-material hat-shaped member with high specific strength and high specific stiffness, the effects of surface treatment for Mg Alloy and hot-melt adhesive film on the bonding strength were clarified from tensile shear tests of thermally welded CFRTP and Mg alloy. In addition, three-point bending tests were conducted on multi-material hat-shaped members that were fabricated by press-injection hybrid molding. The effects of the surface treatment for Mg alloy and hot-melt adhesive film on the bending properties of the hat-shaped members were clarified. When CFRTP and Mg alloy were heat welded, the use of chemical-treated Mg alloy showed higher bonding strength than that of untreated Mg alloy; and the use of hot-melt adhesive film showed even higher bonding strength. In the three-point bending test of the multi-material hat-shaped member, when stacked CFRTP laminate and Mg alloy were used as the surface material, the use of chemical-treated Mg alloy showed higher maximum load and stiffness. Meanwhile when the hot-melt adhesive film at the bonding interface between the CFRTP laminate and the Mg alloy was used, the highest maximum load and stiffness were obtained. However, as there was no significant difference in the maximum load and stiffness between untreated and chemical-treated Mg alloy when the hot-melt adhesive film was used, chemical-treatment for Mg alloy is not necessary.