Determination of a Shape- and Size-Independent Material Modulus for Honeycomb Structures made by Fused Deposition Modeling

The purpose of the project is to study how the mechanical properties of cellular structures made by Fused Deposition Modeling (FDM) change depending on the number of unit cells and the cell geometry. Specimens with three geometries of regular hexagon, square, and equilateral triangle were produced by FDM. The number of cells was varied systematically in each of the three geometries. The samples were tested for compressive strength. The specimens were laser-scanned to determine the actual dimensions, and those values were used in calculations to reduce the dimensional errors. Based on the calculations and analysis, it was concluded that for each geometry, the material modulus converged to a limiting value as the number of unit cells approached "infinity", and the convergent values of the material modulus were approximately the same (within 10% of error) for the three geometries. The convergent values for the material modulus of the hexagon, square, and triangle geometries were 273ksi, 248ksi, and 262ksi respectively. The percentages of error of the square and triangle geometries with respect to the hexagon geometry were 4.0%, and 9.2%, respectively.