Study On Mechanical Performance And Manufacturing Process Of Alternating Pin-press Method For Pyramid Lattice Structure Of 6061 Aluminum Alloy

The three-dimensional lattice structure is widely used in various important fields because of its multi-functional characteristics such as light weight,high strength,heat insulation,noise reduction and high energy absorption efficiency.In this thesis,the alternating pin-press method is applied to the preparation of the pyramid lattice core of 6061 aluminum alloy.After that,the lattice structure is prepared by cementing the panel and core,and its static and dynamic mechanical properties are studied by experiments and finite element simulation.The main contents are as follows:(1)Study on the forming process of aluminum alloy pyramid lattice core.The influence of temperature on the formability of 6061 aluminum alloy was studied by hot tensile test combined with microanalysis.Lattice core was formed by alternating pin-press method at different temperatures,and optimized process parameters of aluminum alloy by alternating pin-press method were obtained.(2)Study on the connection process of the surface and core.The influence of phosphoric acid anodizing treatment parameters on the tensile shear strength of the bonding was studied by response surface method.The parameters of phosphoric acid anodizing treatment were determined,and the bonding curing mold with lattice structure was designed.Based on this,the complete aluminum alloy pyramid lattice was obtained by the bonding process.(3)Study on the static mechanical performance of aluminum alloy pyramid lattice prepared by alternating pin-press method.Flat compression,bending and shear experiments were carried out to study the deformation rule and failure behavior of lattice structure under different static loads.The corresponding finite element simulation was carried out to verify the correctness of the simulation model.The stress distribution of lattice bearing deformation is studied with the experimental results.In the flat compression experiment,the lattice core buckling deformation is resistant to compression load,and the stress is mainly concentrated in the rib deformation region.In the bending experiment,plastic deformation occurs in the middle of the panel under compression,and the stress is mainly concentrated in the middle bearing position.In the shear test,the main failure modes are tensile fracture of the bars and degumming cracking of the joints,and the stress mainly concentrates on the joints.(4)Study on the dynamic mechanical performance of the aluminum alloy pyramid lattice prepared by alternating pin-press method.The effects of impact energy and impact position on the load-bearing and energy-absorbing characteristics of lattice structure were analyzed.Experiments show that with the increase of impact energy,the lattice deformation becomes more severe and the energy absorption efficiency is improved due to the interaction of failure forms such as bar buckling and panel cracking.The initial peak load of the lattice is higher when the impact position is directly above the node.When the impact energy is low,the energy absorption efficiency of the lattice is higher while the impact position in the center of the back panel of the node.When the impact energy is high,the energy absorption efficiency of the lattice is higher while the impact position is directly above the node.Then,the finite element simulation was carried out to study the deformation and stress distribution of the lattice under the impact of falling hammer.The energy-load curves obtained from the simulation and the experiment have good consistency.