| With the global energy exhaustion,the aerospace and automobile fields pay more and more attention to reduce cars weight to save energy.The automobile lightweight has gradually become the development trend of the automobile industry.Due to its light weight and high strength,carbon fiber reinforced composite(CFRP)has become an ideal material to replace traditional steel and aluminum,so it inevitably involves the connection methods between metal and CFRP.DP590 steel is widely used in automobile field due to its good anti sag and anti-fatigue properties.Therefore,this paper focuses on the bonding and bonding-rivet between DP590 dual phase steel and CFRP.In this paper,the effects of different surface treatments on the surface micro-properties of steel and CFRP were investigated,including sandpaper polishing,alcohol ultrasonic cleaning,sandblasting and laser cleaning.The surface micro-morphology,roughness,surface energy,contact angle,surface chemical composition and surface element content of steel after different surface treatments were measured by SEM,XPS,contact angle measuring instrument and surface profilometer.The experiments of adhesive bonding and bond-rivet joints of steel and CFRP after different surface treatment were carried out.The mechanical strength of different bonding and bond-rivet joints was measured by universal testing machine to explore the best surface treatment process.The finite element software ABAQUS is used to simulate the tensile process of the adhesive bonding and the adhesive bonding-riveted joint,analyze the failure mode and mechanism.The results show that mechanical treatment(sanding,sandblasting)and laser treatment can improve the surface roughness,reduce the contact angle and improve the surface energy.In addition to changing the micro morphology of the steel surface,laser treatment can also make the steel surface partly melted,the crystal structure changed,the oxide layer increased,the chemical composition and polar functional groups increased,which is not available for mechanical treatment.In addition,the contact angle between water and formamide after laser treatment is far smaller than that after mechanical treatment.With the increase of energy density,the effect of laser treatment becomes better.When the overlap ratio is 50%,the effect of laser treatment is better than that without overlap.The results show that mechanical treatment and laser treatment can improve the bonding strength,and laser treatment has the best effect.For E-120 HP adhesive,laser treatment under appropriate parameters can increase the joint strength by 640%,and the failure mode changes from interface failure to cohesion failure.For PU6700 adhesive,the joint strength also increased from 5.6MPa to 10.67 MPa,but the failure mode was still the mixed failure of interface and adhesive layer.By comparing experimental shear curve with simulation curve of ABAQUS bonding and bonding-rivet model,it is found that the adhesive bonding model can accurately match the shear curve,the front section of the shear curve of the adhesive bonding-rivet model is accurate,and the back section has some differences,but the trend and ultimate load are basically accurate,indicating the accuracy of the bonding and glue riveting models. |
