###### Abstract  
Graphene/copper matrix composites have a wide range of application prospects, but the mechanical properties of the interface have been one of the key problems restricting their wide application. In this paper, the mechanical behaviors at the interface of graphene/copper matrix composites, such as pulling up, pulling out, and cohesion, and the effects of temperature and graphene content on them were studied by the molecular dynamics method. The results show that the pull-up force and cohesiveness show two stages in the whole process. The pulling force increases rapidly and then decreases to 0 slowly. The pull-out force shows three stages: it rises rapidly at first, then fluctuates continuously, and finally drops to 0. The mechanical properties of the interface deteriorated with the increase in temperature. When the temperature increased from 0 K to 1100 K, the interface normal strength, shear strength, and cohesion strength of the interface decreased by 26.3%, 32.9%, and 24.8%, respectively. In addition, with the increase in graphene content, the normal strength of the interface increases, the shear strength decreases, and the cohesion strength almost stays the same. When the graphene content increases from 6.71 at% to 11.75 at%, the normal strength increases by 6.8%, while the shear strength decreases by 37.4%. The influence mechanism of temperature and content is explained from the aspects of the influence of atomic thermal motion and the hindering effect of graphene on the dislocation motion of the copper matrix. The relevant results have certain reference values for the engineering application and theoretical research of graphene/copper composites. graphene; copper; strength; interface properties +
Footnote †: journal: Applied Sciences  
[PERSON] et al. [16; 17] systematically studied the shear and frictional properties of graphene/copper matrix composites by molecular dynamics method. The results showed that the shear strength of the composites increased with the increase in the volume fraction of graphene. In addition, the size of the defect diameter in graphene also has a direct effect on the strength of the composite. In terms of frictional properties, graphene can improve the surface morphology of materials, making the surface smoother, and reducing the friction coefficient of 64.4-72.9% under different pressing depths. [PERSON] et al. [18] revealed the self-lubricating behavior and friction process inside the composite materials through the molecular dynamics method. Van der Waals gap will be formed between the matrix and graphene sheets, which will reduce the sliding resistance and show the effect of lubrication. [PERSON] [19] simulated the friction behavior of silicon needle on the surface of bare copper- and graphene-coated composites using molecular dynamics method, and concluded that the friction behavior mainly occurred between silicon needle and graphene film. [PERSON] et al. [20] has theoretically studied the bonding, stripping, and folding behavior of graphene on different surfaces of single-crystal copper. The results show that the number of graphene layers on the copper surface can be distinguished by a simple spelling test. Further studies of graphene folding/unfolding on Cu surfaces have shown that Cu(111) is beneficial for monolayer graphene growth. Other researchers [21; 22] have also prepared graphene/copper matrix composites through different methods, and the results all show that graphene can enhance the mechanical properties of the composites to varying degrees, such as compressive strength and hardness. Although there have been many studies on graphene/copper composites, there are still many problems in the interface properties, such as the influence of extreme environments such as high temperature and high loading rates on the mechanical properties of the interface. In this paper, the pull-out, pull-out, and cohesion of graphene/copper composites were studied by the molecular dynamics method.