Stiffness design method of Gyroid-based functionally graded lattice structures with variable porosity controlled by load path

The design of functionally graded lattice structure (FGLS) with triply period minimal surface can better improve the specific stiffness, strength, and energy-absorption capacity. However, how to design the porosity distribution and accurately control structural stiffness is a challenging task. This paper presents a stiffness design method of Gyroid-based FGLS based on variable porosity controlled by load paths. The continuous space iterative subdivision search method is established to calculate the minimum distance from central coordinate point of the cell to the main load paths. Then the mapping relationship between minimum distance and cell porosity is established. The influence of the dispersion range of cell porosity on mechanical properties is further analyzed. It was found that the mechanical properties increase with the increase of dispersion range. Next, cantilever beam and three-point bending beam are taken as the research object, and the FGLSs of the two models with bidirectional gradient are redesigned. The simulation and experimental results show that the stiffness of bidirectional gradient FGLSs is better than uniform density lattice structure under the same volume fraction. This method can accurately and explicitly controls the porosity of each cell by load path, thereby improving the overall structural stiffness.