Research On Mechanical Behavior Of Magnesium Alloy Hybrid Sandwich Panel With Various Configurations Of Lattice Cores

Hybrid lattice sandwich panels are composed of lattice core layers and metal panels.Due to the abundant and regular porosity of lattice core materials,they have obvious advantages over traditional structures in mechanical properties,such as specific strength,specific stiffness,energy absorption and shock absorption.In this paper,a new lattice sandwich panel(LSP)was fabricated by using AZ31 B magnesium alloy plate and 3D-printed polylactic acid(PLA)micro-lattice material,and its three-point bending performance was studied by means of experiment tests and numerical simulations.On this basis,the dynamic mechanical characteristics under low-speed impact loading were further studied.In addition,ISIGHT software was used to conduct multi-objective optimization for lattice cells,and the impact performance of the sandwich panel before and after optimization was analyzed.In order to better describe the constitutive behavior of FDM 3D-printed PLA material in finite element simulation accurately.The stress-strain relationship of the material is obtained by tension test firstly,and the constitutive model with damage variable is used to fit the relationship,and the material model is introduced into ABAQUS/Explicit by VUMAT subroutine.In addition,the cohesive model with an exponential T-S relationship is introduced through cohesive unit and VUMAT subroutine for bonding layer.For damage morphologies and mechanical properties of BCC hybrid lattice laminates under three-point bending,the simulation results are consistent with the experimental data,showing the validity of the numerical model.Furthermore,the three-point bending process of the composite lattice sandwich panels with four types of body-centered cubic(BCC)derived lattice configurations is simulated by FEM.The results show that the bending resistance of the composite lattice sandwich panel is superior to that of the PLA sandwich plate.BCCG sandwich panel with gradient distribution of Z-strut has higher shear resistance and fracture collapse resistance.In addition,the core structure and core density have a coupling effect on the bending resistance of LSP significantly,so the sandwich structure with optimized and lower core layer density can have better bending resistance.In order to explore the influence of core layer on the impact resistance of composite sandwich panels,the low-speed impact process was simulated in this paper.Multi-objective optimization for the BCCG cellular configuration was carried out based on ISIGHT software by considering maximization of the specific stiffness and the specific plastic platform strength.By comparing and analyzing the impact simulation results of hybrid sandwich plates with the different core layers,it is found that compared with the PLA lattice,aluminum alloy sandwich panel has better impact stiffness and strength,and can maintain better structural morphology after impact,but its peak impact force is higher.Furthermore,the optimized lattice core layer can enhance the impact strength and reduce the impact induced deformation deflection of the sandwich panels,and improve its local fracture failure and the energy absorption characteristics.