Manufacturing And Properties Of Two-dimension Lattice Composite Structures

A carbon fiber reinforced epoxy composite load-carrying cylinder with lattice structure was studied in this paper. Research was focused on design, manufacturing process and loading capacities of the lattice structure under axial compression loadings.A finite element model (FEM) of two-dimension Lattice Composite Structures (2D-LCS) was built. The analyzed results show that helical ribs of the lattice structure were in compresion and the circumferential ribs were in tension under the compression loads; high shear stress can be observed in circumferential ribs; the most possible failure mode of the lattice structure is the broken of helical ribs under compression stress and the broken of circumferential ribs under shear stress.Effects of structural parameters of the lattice on load-to-weight ratio and integral stiffness of the composite lattice structure were studied and the optimum structural parameters were obtained. Results show that the composite lattice structure would have the best load-to-weight ratio and integral stiffness as the helical angle was between 30°and 36°and the equivalent parts of the 2D-LCS bottom perimeter is set to 20. The ultimate load and integral stiffness both increased linearly as the width or height of ribs increased. The optimum configuration parameters of composite lattice structures with given outer diameter and length were: helical angleφ=30°, the width b and the height H of ribs satisfy with H≥b and the equivalent parts of the 2D-LCS bottom perimeter should be 20.The manufacturing process of 2D-LCS cylinders was investigated. The 2D-LCS cylinders were fabricated successfully by filament winding process on a silicon rubber mould. Effects of resin system and winding fiber tows on quality of 2D-LCS cylinders were studied, and optimum process paremeters were obtained.Composite undirectional laminates with the same Vf (fiber volume fraction) of 2D-CLS cylinders were fabricated. Properties of the laminates in tension, compression, bending and shearing were tested. The testing results show that T700/E-51 composite undirectional laminate with 22.2% of Vf are of the longitudinal tensile strength of 871.6 MPa, the longitudinal tensile modulus of 50.1GPa, the longitudinal compressive strength of 555.8MPa, the bending strength of 630 MPa and the shear strength of 47.3MPa, respectively.Axial compressive property of the 2D-LCS cylinders was tested. Experimental results show that the maximum compressive load, load-to-weight ratio and stiffness of T700/E-51 2D-LCS cylinders were all higher than that of Glass fiber/E-51 2D-LCS cylinders. The maximum compressive load, load-to-weight ratio and stiffness of the T700/E-51 2D-LCS cylinder is 183.77kN, 69.35kN/kg and 71.94kN/mm, respectively. The dominated failure modes for the 2D-CLS cylinders were delamination and fracture of the helical ribs.