Study On The Mechanical Properties Of Epoxy Resin Adhesive Modified By Nanoparticles

With the rapid development of automobile industry,the use of new lightweight materials poses new challenges to the connection technology between components.Compared with the traditional connection method,structural bonding has the advantages of no damage to the surface of the connected parts and low stress concentration,which has been more and more widely used.However,due to the brittleness of the cured polymer,the application of epoxy adhesives in many fields is limited.In order to overcome this limitation,meet the demand of automotive industry for high strength and high modulus epoxy resin,and take into account the cost and economy at the same time,the epoxy resin was modified by filling nanoparticles to obtain composite materials with higher comprehensive mechanical properties,which has become a research hotspot in engineering and academic fields in recent years.Based on the above background,silica nanoparticles and superparamagnetic Fe₃O₄ nanoparticles were selected in this paper,and Araldite^?AY105-1/HY 991 epoxy resin was modified according to the mass fraction of 1wt%,3wt%and 5wt%.The preparation process of dumbbell-shaped specimen,double cantilever beam specimen,end notch bending specimen and single lap joint was developed.The mechanical properties under typical loading conditions were tested.In order to verify the accuracy of the finite element model,a three-dimensional finite element simulation model of single lap adhesive joint was established,and the degree of agreement between the tensile shear test results and the simulation results was compared and analyzed.The specific research contents include:（1）The dumbbell-shaped specimens of nano particle modified epoxy resin adhesive were prepared,and the quasi-static tensile test was carried out to obtain the elastic modulus and failure strength of different nano particle modified adhesives.The double cantilever beam specimens and end notch bending specimens of nano particle modified adhesive were prepared,and the mode I/II fracture energy of corresponding specimens was obtained by loading test of mode I/II fracture characteristics.The above tests constitute the determination of the typical loading parameters of nano particle modified epoxy resin,and the test data are used in the subsequent definition of material property parameters of finite element simulation.（2）Using carbon fiber 0°/90° cross-ply CFRP as the substrate and epoxy resin as the bonding agent,the nano particle modified adhesive single lap joint was prepared.Then the quasi-static tensile shear loading test was carried out to obtain the load displacement curve of the joint and the corresponding failure load of the specimen;ABAQUS software was used to define the material parameters and establish a three-dimensional finite element model of single lap joint to simulate the quasi-static tensile shear loading adhesive layer failure process.The simulation results are compared with the experimental results to verify the accuracy of the finite element model.The results show that the elastic modulus,tensile failure strength,mode I fracture energy,mode II fracture energy and shear failure load of the epoxy resin modified by the two kinds of nanoparticles are improved at the mass fraction of 1 wt.%and 3 wt.%;When the mass fraction of particles is 5wt.%,the above mechanical properties are inconsistent.Compared with the two kinds of particles,the mechanical properties of epoxy resin were improved more obviously by silica nanoparticles.The results show that the failure load test curve of the single lap joint is in good agreement with the simulation curve,which verifies the reliability of the finite element modeling in this paper,so as to provide reference for the test and modeling of the mechanical properties of adhesives and the modification methods of adhesives based on nanoparticles.