The Fabrication And Mechanical Properties Of Pyramidal Lattice Stitched Foam Sandwich Composites

With unique structure, the lattice enhance foam sandwich makes up the deficiencies of the foam sandwich in interface is weak and the shortage of the strength stiffness in all directions. The novel structural composites well satisfy the requirements for light weight and high strength of the materials for high technology, such as aeronautics and astronautics etc. The existent researches were mostly focus on the theoretical analysis of the mechanical properties of the lattice stitched foam sandwich while the research of its failure mechanism and dynamic damage were little.In this paper, a weaving method was suggested to fabricate carbon fiber reinforced lattice enhance foam structures. By the contrast analysis lattice stitched foam structures and foam structures in compression, shear and 3-point bending test. The results showed that the lattice core in stiffness and strength of lattice stitched foam structures has significantly enhanced role. The mechanical properties model predicting of the lattice stitched foam sandwich structures was established based on the periodic unit cell. The theoretical values of stiffness and strength of the lattice stitched foam sandwich structures were calculated using homogenization theory and introduction of end restraint correction factor.Theoretical and experimental values were compared, failure mode is given a reasonable explanation.The FE software, ABAQUS was also employed to research low-velocity impact response and failure mode of lattice stitched foam sandwich and foam sandwiched composite. while the Hashin criteria gave an insight about the failure of the face sheets. Comparative experimental and simulation results show thatlattice core enhanced obviously for sandwich structures at low impact energy,The load-time curves, energy absorption and failure mode were obtained to compare the numerical and experimental results at several impact energy levels has a good agreement. It was observed that the damages at the core can be classified as foam cracking or foam crushing and the core rod buckling and crushing. Damages to the face sheet were through matrix cracking and delamination. Pyramid lattice stitched foam sandwich structure of this study has a higher specific stiffness and specific strength compared to the foam sandwich structure, and can be designed easily, will be applied to other lattice reinforced foam sandwich structure.