Preparation And Mechanical Property Analysis Of Novel Hybrid Sandwich Structures With Lattice Cores

Hybrid lattice sandwich panels are composed of lattice cores and metal face sheets.Compared to a traditional single-layer plate,the sandwich structures with high porosity lattice cores show superior performance in terms of weight reduction,energy absorption,cost reduction and production time,etc.Thus,the sandwich panels have been paid more and more attention in the aerospace,automobile and other fields.In practical applications,lattice-core sandwich panels are often subjected to external compression and impact loads,resulting in deformation and damage or even interface debonding.Therefore,it is particularly important to study and analyze the static and dynamic properties and heterogeneous interface of lattice-core composite sandwich panels with AZ31B magnesium alloy face sheets and modified polylactic acid?PLA?lattice cores.In this paper,the material model of modified polylactic acid was obtained by the fused deposition modeling?FDM?3D printing technology.On this basis,the mechanical characteristics of four lattice topologies with body-centered and face-centered structures under quasi-static compression loading were analyzed numerically.The validity of the numerical model was conducted through theoretical derivation and comparison with existing results.In order to enhance the interface bonding properties between the AZ31B magnesium alloy face sheets and the PLA lattice cores,the surfaces of the magnesium alloy face sheets and the modified PLA lattice microgroove structure were preprocessed by using the mechanical and chemical treatment methods.Then,the interface parameters of the heterogeneous bonding layer were obtained through experiments.Based on the exponential cohesion model,VUMAT subroutine of the interfacial layer was written and verified.In addition,the impact simulation by using the interfacial subroutine was carried out for the hybrid AZ31B magnesium alloy skin and PLA lattice-core sandwich panels with high energy absorption characteristics under static compression.Finally,the influence of the bonding interface,impact position and matrix material on the dynamic impact characteristics of the lattice-core sandwich composite structure is further analyzed.Results are as follows:Compared with the body-centered cubic structure?BCC?and face-centered cubic structure?F₂CC?,the BCCZ and F₂CCZ lattice configurations with Z-direction pillars exhibit better quasi-static compression characteristics,and they have higher equivalent elastic modulus,peak stress and energy absorption characteristics.Interlayer fracture toughness values G_ICC and G_IICIC of the interface between the AZ31B magnesium alloy face sheets and the modified PLA microgroove lattice cores can reach up to 0.47kJ/m² and8.32 kJ/m²,respectively.Compared with the interface parameters between the AZ31B magnesium alloy face sheets and the modified PLA lattice cores with smooth surface,the interface strength is significantly improved.Under dynamic impact loading,the sandwich panels with F₂CCZ lattice cores exhibit better impact resistance than that of the sandwich panels with BCCZ lattice cores.In addition,the impact position has a great influence on the deformation and damage evolution of the lattice-core sandwich composite structure.Compared with the modified PLA lattice-core sandwich panel,it is found that the titanium alloy lattice-core sandwich panel with the same mass fraction has better impact stiffness and strength.