Testing And Modeling Of Steel And Aluminium Joints With Flow Drilling Screws

With the continuous consumption of global energy,the automotive industry will pay more and more attention to lightweight development.The development trend of automotive lightweight is bound to apply more lightweight materials to the automotive field,which places higher requirements on the connection process.In today’s aluminum body joining process,aluminum spot welding and SPR riveting are widely used,but the characteristics of aluminum alloys,such as strong thermal conductivity,easy oxidation,and large linear expansion coefficient,bring great difficulties to welding.Especially in the case of steel-aluminum hybrid connection,spot welding cannot be used at all,and there are many cavity structures on automobiles,and SPR riveting is also limited.The single-sided connection advantage of the FDS process can solve this problem.Therefore,it is extremely important to study this process,especially in the case of steel-aluminum hybrid materials.This paper mainly conducts mechanical performance test and simulation research on steel-aluminum mixed plates connected by the FDS process.Firstly,the principle and advantages and disadvantages of the process are briefly introduced,and a new type of detachable screw is designed based on the disadvantages.Then,the influence of the following variables on the plates connected by the FDS process is discussed through experiments,such as the combination order of steel and aluminum plates,pre-punching and pre-punching positions;Then,based on the experimental basis,the detailed solid simulation model was established and solved,and the simulation results were relatively consistent.The model has a guiding significance for the future virtual simulation of the mechanical properties of the FDS process.Finally,based on the fine solid simulation model,the equivalent simplified model of solid screw is established accurately,which greatly reduces the cost of virtual simulation.In addition,the mesh free particle algorithm is introduced to study the FDS process,and the Eulerian algorithm and fluid structure coupling method are used to simulate the hot melt drilling process.The test research shows that under the combination of steel and aluminum mixed plate,the aluminum plate under the steel plate is more conducive to improving the connection strength of the process.The internal reason is that the aluminum plate under the steel plate will be more conducive to the formation of longer bushings and longer threads effective connection length,thereby improving connection strength;Secondly,it is obvious that the connection strength of the pre-punched hole is lowerthan that of the non-opened hole,but when the product part does not need a large connection strength,it is necessary to consider the high strength of the upper plate material and the processing cost.Finally,for the combination of three-layer plates,the connection strength of the top plate with pre-punched holes is higher than that of the middle plate.In addition,a large number of simulation studies on the FDS process have been carried out in this paper.The virtual finite element simulation method has always been an important means of process product design,and the various simulation models established this time have been successfully matched,which has guiding significance for further research on the FDS process.