Investigation Of Bending And Buckling Behavior Of Sandwich Beams With Asymmetric Graded Lattice Core

The lattice sandwich structure is a new type of lightweight multifunctional structure with excellent mechanical properties,which is widely used in aviation,aerospace,shipping,transportation and other fields.However,the traditional lattice structure is a uniform structure composed of periodic unit cells.In engineering practice,the structure is often subjected to local concentrated loads or asymmetric loads,which cannot fully exert its load-bearing efficiency.In order to further improve its load-bearing capacity,this paper proposes as a new type of asymmetric graded lattice sandwich structure.And based on the classic ALLEN sandwich beam theory,the bending and buckling characteristics of asymmetric graded lattice sandwich structure are systematically studied by theoretical analysis and finite element simulation.The main contents are as follows:Firstly,the representative volume element is taken as the research object.Based on the unit cell equivalent theory,the unit cell equivalent elastic constant and equivalent strength of the asymmetric graded lattice sandwich beam are calculated.By linear fitting method,the graded lattice structure of discontinuous medium is equivalent to the graded material of continuous medium.And based on the classic ALLEN sandwich beam theory,a theoretical calculation method for asymmetric graded lattice sandwich beam with arbitrary core properties is proposed.At the same time,the script program is written in Python language to realize the parametric modeling of the asymmetric graded lattice sandwich structure,and the finite element analysis is carried out.The calculation results are compared with the theoretical analysis results to verify the correctness of the equivalent theory in this paper.Secondly,the bending performance of the asymmetric graded lattice simply supported beam under the action of three-point bending load is studied.The deformation hypothesis of asymmetrical graded lattice simply supported beam is presented and its theoretical model is established and the theoretical formula for predicting the mechanical properties of the structure under three point bending load is derived through improving ALLEN’s classical theory.Four asymmetric graded lattice sandwich structures with different structural parameters are designed,and the corresponding numerical simulation analysis is carried out to verify the accuracy of the theoretical model proposed in this paper.Thirdly,the bending behavior of the asymmetrical graded lat tice cantilever beam is investigated.The theoretical model of the asymmetrical graded lattice cantilever beam under uniform distribution load is established and the theoretical formula for predicating the mechanical properties of the structure is derived,which are verified by numerical simulation.Three kinds of structures with the same mass but different graded distribution are designed and the influence of gradient coefficient and geometric parameters on the mechanical properties of the structure of asymmetric graded lattice cantilever beam is investigated.Finally,the overall macroscopic buckling of an asymmetric graded lattice sandwich structure under in-plane load is studied.A theoretical model of an asymmetric graded lattice sandwich structure under in-plane load is established.The calculation formula of critical buckling load of the structure under simply supported boundary is derived by energy method,which is verified by numerical simulation.The influence of structural geometrical parameter s on the macroscopic buckling performance of the sandwich beam with asymmetric graded lattice is studied through the combination of theoretical analysis and numerical calculation.