Fabrication And Mechanical Performance Of New Composite Pyramidal Lattice Structures

Since the composite lattice truss core sandwich structure has the high specific strength and high specific stiffness, it has attracted more and more attentions in recent years. At present, two bottleneck problems that restrict the application of the composite lattice truss core sandwich structure are to reduce the preparation cost and to further improve the mechanical properties. For this purpose, this paper proposes a new preparation method for the composite lattice truss core sandwich panel in which the lattice core is integrally strengthened and the core rod is reinforced with unidirectional fibers.Chapter One introduces the background and current status of the composite lattice truss core sandwich structure and demonstrates the overall structure and main contents of this paper.Chapter Two describes the fabrication technology of the composite pyramid lattice truss core structure. Using the present fabrication technology, we has sucessfully manufactured this new composite lattice structure. The proposed fabrication technology has the following advantages:(1) The bonding strength between the core and face-sheets can be effectively enhanced by increasing the bonding area between the upper(lower) metal connectors and the upper(lower) face-sheets;(2) The lattice truss core has the ability of collaborative deformation and can jointly resist the appied load after it is integrally strengthened by the upper and lower metal connectors;(3) When fibers are paved along the rod direction, the lattice truss core has the maximum load-carrying efficiency;(4) Materials are not wasted and more fully utilized by using the present fabrication technology.The out-of-plane compressive performance of the composite pyramid lattice structure have been investigated in Chapter Three, including the theoretical prediction of out-of-plane compressive stiffness, out-of-plane compressive strength and failure modes, out-of-plane compressive tests and finite-element simulations. The results show that the new composite pyramid lattice structure manufactured by the present fabrication technology has the significant advantages compared with other existing composite pyramid lattice structures.The shear performance of the new composite pyramid lattice structure are then investigated in Chapter Four, including the theoretical prediction of shear stiffness, shear strength and failure modes, shear tests and finite element simulations. The results show that the shear performance of the composite pyramid lattice structure has been effectively improved by designing metal connectors which increase the bonding area between the core and face-sheets.In a word, for the preparation of composite lattice sandwich structures, the fabrication technology proposed in this paper has overcome some deficiencies of the existing techniques, and provides a new way for the preparation of composite lattice sandwich structures.