The functional hierarchical structures of the triply periodic minimal surface are receiving much attention in tissue engineering applications due to their lightweight and multifunctionality. However, current functionally graded structure design methods are not friendly to heterogeneous structures containing different orientations and different unit types and often face the problems of insufficient connection in the hybrid regions and low local stiffness. In this paper, an improved gradient structure design method was proposed, which solves the problem of insufficient connection between substructures by constructing hybrid region transition functions. Three improved heterogeneous structures were constructed using Primitive and Gyroid lattices and compared with the unimproved heterogeneous structure. Their mechanical properties, deformation mechanism, and energy absorption capacity were examined by finite element analysis and experiments. The results showed that the proposed design method can effectively solve the problems of insufficient connection and poor bearing capacity in the hybrid region between substructures. This method can not only ensure the full connection of the hybrid regions but also flexibly adjust the mechanical properties and energy absorption capacity as well as effectively expand the application range of the energy absorption. Overall, these findings provide valuable guidelines for designing gradient structures with disordered and hybrid features.
Keywords: additive manufacturing; energy absorption; mechanical properties; scaffold; structural design.