Influence of conical graded porous architecture on the mechanical, failure behavior and fluid-flow properties for bone scaffold application

Abstract

IntroductionThe advanced design of the controllable hierarchical gradient architecture of functionally graded porous scaffold is gaining increasing attention in tissue engineering (TE). This paper proposed a new design gradient concept of Schwartz-Primitive (Sch-P) conical graded porous architecture by integrating linear and radial graded patterns. Materials and Methods: Four types of gradient pattern structures with similar 80 % porosity were designed and fabricated using polylactic acid (PLA) pro via material extrusion. The structural compression test was performed to evaluate the mechanical properties in order to validate the computational analysis. In addition to that, computational fluid dynamics (CFD) was conducted to predict the permeability and fluid-induced wall shear stress (WSS) of porous structures. Results: The experimental result shows that conical graded structures exhibit the highest mechanical strength in terms of elastic modulus (64.84 MPa), yield stress (1.83 MPa), and total energy absorption (1.115 J/m3) compared to linear, radial, and uniform structures. The unique smooth surfaces of the conical pores arrangement resulted in excellent strength with a localized fracture in the shape of a chevron and global fracture in a layer-by-layer failure mechanism. Indeed, the permeability values for conical graded meets the fluid permeability of actual cancellous bone. Conclusion: The findings highlighted that conical graded structure offered superior mechanical characteristics with improved energy absorption and failure behavior as well as fluid-flow properties. It indicates that conical graded meets all the mechanical and biological requirements to mimic the cancellous bone, especially in load-bearing applications.