Effect Of Surface Topography On Shear Performance Of FRP/Metal Adhesive Parts

Fiber reinforced polymer(FRP)bonded with metal materials can give full play to the excellent properties of the two materials.By means of bonding technology,the impact toughness of FRP and the fatigue properties of metallic materials were all improved.FRP bonded with metal materials applied in the Strengthening and repairing of the bearing metal structure in large equipment such as ships and bridges can obviously improve the bearing capacity of the metal structure.The bonding interface between FRP and metal materials is the weakest in the whole structure.In the use of FRP strengthening and repairing metal structure,the bonding interface is often subjected to various shear loads.Excessive load will cause interlayer cracks between FRP and metal.When the crack extends to the whole interface,it will cause bonding failure.Surface topography of metals is an important factor that affecting the shear strength of FRP and metal bonding structure.The study of effect of surface topography on the shear properties can provide theoretical basis for improving the shear strength and ensure the reliability of the FRP and metal bonding application.In this paper,different types of sandpaper are used to grind aluminum alloy surface to obtain different metal surface topography.Single lap specimens of FRP and aluminum alloy were prepared by CO curing process.The shear test was carried out to study the relationship between roughness parameters Rc(mean height of profile elements),Rsm(mean width of the profile elements),Rlo(developed length)and shear strength.On this basis,the change trend of shear strength with the ratio of Rsm to Rc is studied.In addition,short fibers was added to adhesive to improve the structure's toughness and the 3ENF test was carried out to study the effect of different surface topography.The results show that too rough surface is not conducive to the bonding of GFRP and aluminum alloy.When the ratio of Rsm to Rc is in a reasonable range,the adhesive can fully fill the surface profile of aluminum alloy and Rlo is the main influencing factor of bonding strength.When short fiber is used for toughening,high surface roughness is more suitable for bonding.