Mechanical behaviors of multidimensional gradient gyroid structures under static and dynamic loading: A numerical and experimental study

Sophisticated gradient designs in natural materials are usually desired in man-made cellular materials with the aim to achieve multifunction and improve structural performance. However, many natural structures are still difficult to mimic due to their complex gradient designs. In this paper, a novel design strategy is proposed for generating multi-dimensional gradient gyroid structures, which have the ability to mimic complex gradient pore characteristics. The novel design strategy is based on the topological constants instead of thickness, cell size and porosity. Moreover, it adopted the interpolation function to bridge the gap between adjacent pore gradients. Five gradient gyroid structures from one-dimensional, two-dimensional to three-dimensional (1D, 2D to 3D) space were generated as examples using this design method. A numerical method is developed to assess the mechanical response of proposed structures incorporating the rate-dependent properties under varying impact loading velocity. Functionally graded metallic gyroid structures were fabricated using selective laser melting and its experimental results were used to validate the numerical model under both quasi-static and dynamic compression. Then the load-bearing capacity of these gradient gyroid structures under different loading velocities was investigated. According to the results from the numerical analysis, the gradient design of gyroid structures has a substantial impact on the deformation modes and load-bearing capacity. Gradient design in gyroid structures is capable of providing excellent specific energy absorption and demonstrates tremendous promise for managing deformation behaviors. 3D gradient design exhibits the best loading bearing capacity among 1D, 2D gradient ones and traditional triply periodic minimal surface structures (including gyroid, diamond, Primitive, F-Koch and IWP). The multidimensional gradient design strategy proposed in this study showed the ability to mathematically control the complex gradient pore characteristics, which can be applied to the design of functionally graded structures for efficient energy absorption also in modern composite structures.