Study On Mechanical Performance Of Interface Between CFRP Laminate And Steel Connected By The Film Adhesive

CFRP is widely used in the field of structural reinforcement because of its excellent mechanical properties and good durability.In the reinforcement of steel structure,the bonding performance of interface between CFRP and steel is the key.There are many factors affecting the interface performance,such as CFRP material,adhesive type,adhesive thickness,surface treatment,curing temperature,etc.In this paper,a new high strength adhesive-epoxy carrier film adhesive is used to solve the problems of the common paste adhesives used in structural reinforcement,such as the difficulty of consistency control of the thickness of the adhesive,the difficulty of vertical forming,and the poor high temperature resistance.The mechanical properties of the film adhesive and the interface mechanical properties of CFRP laminate/steel double lap joints were studied experimentally.Specific research work is as follows:(1)The mechanical properties of the film adhesive were tested by DMA(Dynamic Thermomechanical Analysis),and the dynamic mechanical properties temperature spectrum was obtained,and the glass transition temperature was determined.(2)The mechanical properties of interface between CFRP laminate and steel under different curing pressure,bond lengths and ambient temperature were studied.The surface strain distribution of CFRP laminate,interface shear stress distribution,failure mode and force transfer law were analyzed.The curing pressure value used in specimen fabrication was determined,and effective bond length of CFRP laminate at room temperature(25?)were determined.The bond-slip constitutive relationship of interface between CFRP laminate and steel at different ambient temperature was obtained.The bond-slip constitutive parameters of interface bonded with the film adhesive at room temperature(25?)were compared with those of common paste adhesives for structural reinforcement.Based on the existing CFRP laminate/steel bond shear capacity calculation model,The ultimate bearing capacity of the film adhesive-connected joints and common paste adhesives-connected joints were compared.(3)The durability of interface between CFRP laminate and steel was studied by water bath test.The load-displacement curve,surface strain distribution of CFRP laminate,interface shear stress distribution,failure mode and force transfer law were analyzed.The relationship between water bath specimens and non-water bath specimens and the influence of different water bath temperature on interface durability were compared.