Bio-Inspired Toughening of Composites in 3D-Printing

Abstract

Natural materials achieve exceptional mechanical properties by relying on hierarchically structuring their internal architecture. In several marine species, layers of stiff and hard inorganic material are separated by thin compliant organic layers, giving their skeleton both stiffness and toughness. This phenomenon is fundamentally based on the periodical variation of Young’s modulus within the structure. In this study, alteration of mechanical properties is achieved through a layer-wise build-up of two different materials. A hybrid 3D-printing device combining stereolithography and inkjet printing is used for the manufacturing process. Both components used in this system, the ink for jetting and the resin for structuring by stereolithography (SLA), are acrylate-based and photo‑curable. Layers of resin and ink are solidified separately using two different light sources (λ1 = 375 nm, λ2 = 455 nm). Three composite sample groups (i.e., one hybrid material, two control groups) are built. Measurements reveal an increase in fracture toughness and elongation at break of 70% and 22%, respectively, for the hybrid material compared to the control groups. Moreover, the comparison of the two control groups shows that the effect is essentially dependent on different materials being well contained within separated layers. This bio-inspired building approach increases fracture toughness of an inherently brittle matrix material.

Applications of 3D printed bone tissue engineering scaffolds in the stem cell field

“…Step by step, the raw material of unbound powder is finally removed, and a 3D model is constructed [ 47 ]. This technology is usually used in combination with other technologies, such as high temperature burning [ 49 ], stereolithography [ 50 ], or electro-hydro dynamic jetting [ 51 ], etc. The following is a commercial application of a more widely used, but also a combination of a variety of technologies of printing technology.…”

Multimaterial Extrusion‐Based Additive Manufacturing of Compliant Crack Arrester: Influence of Interlayer Length, Thickness, and Applied Strain Rate

“…Architecting materials to improve the fracture toughness without losing strength are emerging trends in materials engineering and often challenging. [1,2] Nowadays, a notable number of promising concept designs are available, most of them inspired by the animate and inanimate nature (e.g., biomimetics [2][3][4][5][6][7][8][9][10] and lithomimetics, [2,11] respectively), while others are born in the minds of scientists and engineers unrelated to nature (e.g., topological interlocking [2,[12][13][14][15] or lattice metamaterials [2,16] ).…”

“…[2] In the field of biomimetics, numerous examples of composites linking high strength and toughness can be found. [7] Well-known examples for such material compositions are nacre [17] or the skeleton of Euplectella aspergillum [18,19] (deep-sea sponge from the Western Pacific), both combining different hard and soft phases to gain outstanding mechanical performance. [6,7,18] Among other mechanisms, the underlying phenomenon providing these improved behaviors can be explained by the material inhomogeneity effect, which has been studied intensively.…”

“…[7] Well-known examples for such material compositions are nacre [17] or the skeleton of Euplectella aspergillum [18,19] (deep-sea sponge from the Western Pacific), both combining different hard and soft phases to gain outstanding mechanical performance. [6,7,18] Among other mechanisms, the underlying phenomenon providing these improved behaviors can be explained by the material inhomogeneity effect, which has been studied intensively. [6,[20][21][22][23][24][25] This effect is caused by the spatial variation of mechanical properties (i.e., Young´s modulus and yield strength).…”

Down to the Bone: A Novel Bio-Inspired Design Concept

“…This increasing need for innovation is fortified by the development of biomimetic science, which deals with the study of biological processes in order to highlight innovative solutions to everyday problems [ 1 ]. Across years of evolution and natural selection, living creatures have resourcefully accomplished a wide range of captivating functions towards optimized performances as a requisite to survive, adapt and interact with their ever-changing complex natural environments [ 2 ]. This field specifically aims at understanding nature’s solutions as a mine of novel design ideas in order to exploit them to find concrete applications [ 3 ].…”