Design Method for Conformal Lattice-Skin Structure Fabricated by AM Technologies

Parts with complex geometry can be produced by additive manufacturing processes without a significant increase in fabrication time and cost. One application of AM technologies is to fabricate customized lattice-skin structures which can enhance the functional performance of products with less material and less weight. In this paper, a brief comparison between different types of lattice structures and their related design methods has been done. The result shows that conformal lattice structures may perform better than other types of lattice due to its unique configuration for some design cases. However, most existing design methods of conformal lattice have a limitation to deal with complex external geometry. To solve this issue and fully utilize conformal lattice structures, a general design method for a conformal lattice-skin structure is proposed. This design method consists of two major design stages. At the beginning design stage, conformal surfaces are selected based on proposed general design guidelines. Then two different lattice frame generation methods are provided to generate conformal lattice to fit the selected conformal surfaces. A comparison between these two methods is made to help designers select a suitable method for their design cases. In the second design stage, the thickness of each lattice strut is calculated based on a defined mapping function. This mapping function generally considers two important factors from the result of topology optimization. They are optimal relative density distribution and its related principle stress direction. Based on the calculated strut’s thickness, the geometry model of heterogeneous conformal lattice can be generated. At the end of the design process, skin structures can be added on the generated heterogeneous conformal lattice. To further illustrate and validate the proposed design method, a design case of handle connector is provided. The result of this case study shows this method can provide an efficient tool for designers to generate the conformal lattice-skin structure for a complex external shape.