| With the rapid development of science and technology in the fields of aerospace and automobile,the requirements for material mechanical properties are getting higher and higher.However,a traditional single material is far from meeting the needs of the application fields,so the development of composite materials has become an inevitable trend.The composite material is a hybrid engineering material,consisting of various single materials,which not only has the characteristics of each component material,but also show some new properties.Carbon fiber composite materials have received extensive attention due to their outstanding mechanical properties.The carbon fiber reinforced metal laminate(FML)is composed of thin metallic sheets and fiber reinforced composite layers at different stacking arrangements by using resin adhesive between layers,which has been applied in many fields.Although the resin binder has the advantages of lightweight and simple bonding process,the interface bonding strength using the resin adhesive is relative low and the heat resistance is poor.Therefore,in practical situations,the interlaminar delamination and damage often occurs,resulting in the performance degradation of the entire structure.This in return restricted the performance development of the FMLs.Therefore,it is rather essential to do the research on bonding properties of the FMLs.First of all,in order to improve the bonding properties of the magnesium alloy based FMLs(Mg-based FMLs),a new type of Mg-Al-Zn solder was self-made.A certain proportion of graphene nanosheets were added as the reinforced phase,which can further improve the bonding ability of the solder.The preparation of graphene was based on the modified Hummers method in which natural graphites were first oxidized into graphene oxides and then graphene oxides were further reduced to graphene nanosheets under the action of reducing agent.Using the above Mg-based alloy solder with and without graphene nanosheets,the AZ31 magnesium alloy sheet and carbon fiber woven fabric were hot pressed into Mg-based FMLs,and their mechanical properties were tested.Through the double cantilever beam and three-point bending experiments,when using the solder without graphene between the adhesive layers,the mode-I and mode-II fracture energies were 0.732 kJ/m~2 and 5.89kJ/m~2,respectively;while graphene was added as the reinforced phase in the Mg-based alloy solder,the mode-I and mode-II fracture energies for the Mg-based FMLs were 0.825 kJ/m~2and 6.20 kJ/m~2,respectively.Compared with the mode-I(0.262 kJ/m~2)and mode-II(5.81kJ/m~2)fracture energies of the resin bonded Mg-based FMLs,the fracture energies of the Mg-based FMLs bonded by the Mg-based alloy solder with or without graphene nanosheets are improved greatly.On this basis,the tensile tests were also carried out for the Mg-based FMLs with different volume fractions.It is found that when the volume fraction of fiber resin composites is 30%,the tensile strengths of the Mg-based FMLs bonded by Mg alloy solder without and with graphene nanosheets were 331.2 MPa and 313.5MPa,respectively,which showed a substantial increment of 10.7%and 4.8%compared to the tensile strength of 299.0MPa for the resin bonded Mg-based FMLs.When the volume fraction of fiber resin composites is 37%,the tensile strengths for the two Mg-based FMLs with and without incorporation of graphene nanosheets can be increased by 29.2%and 35.7%compared to the resin adhesive bonded Mg-based FMLs.In order to predict the dynamic responses of the Mg-based FMLs under medium velocity impact loading,the cohesive model parameters were obtained using inverse analysis method based on the double cantilever beam tests.And then,the numerical simulation of the Mg-based FMLs under various initial velocities(20m/s,35m/and 50m/s)were conducted.The prediction results for the Mg-based FMLs with different configurations under different impact velocities are finally compared,and it can be seen that the overall simulation results were reasonable. |
PDF Full Text Request