Design And Mechanical Behavior Of Composite Lattice Truss Sandwich Structures With Stiffened Facesheets

Composite lattice truss sandwich structures exhibit multifunctional benefits,such as energy absorption and shock resistance,in addition to high specific strength and high specific stiffness,making them have wide application prospects in aerospace.In this paper,we presented a deep research into the preparation technic and mechanical properties of lattice truss sandwich structures with stiffened facesheets.The first chapter introduces the the main purpose and meaning of this research.Published research into composite pyramidal lattice sandwich structure was reviewed.At last,the main contents of this paper were listed.In the second chapter,by altering the geometry of pyramidal lattice sandwich structure,three new kinds of lattice sandwich structures were designed.Method was explored for fabricating the composite panels by combining precision cutting and interlocking process.Besides,the basic mechanical properties of carbon fiber reinforced composite used in this paper were tested.In chapter three,both theoretical and experimental methods were developed to investigate the out-of-plane compressive performances of the three panels.Based on Euler-Bernoulli beam theory,equations were deduced for predicting the equivalent stiffness and strength of the panels under out-of-plane compressive loading.Three-dimensional and two-dimensional analytically based failure mechanism maps were provided to understand the relationship between structure's failure mode and physical dimension.Specimens were designed and tested to observe the typical failure,verifying the correctness of the theoretical model.Based on the experimental results,the load-carrying efficiency and energy absorption efficiency were evaluated.The shear performances of the three panels were systematically studied in chapter four.Analytical models were developed to analyze the shear performances by taking the main failure modes into account.Three-dimensional and two-dimensional analytically based failure mechanism maps of the panels under shear load were provided.shear tests were conducted to reveal the failure mechanisms of pyramidal lattice structure and the three new-designed panels.By comparing the experimental results,it can be concluded that the new designed panels do make the debonding strength remarkably improved.