Revealing the Mechanics of Helicoidal Composites through Additive Manufacturing and Beetle Developmental Stage Analysis

Abstract

Investigation into the microstructure of high performance natural materials has revealed common patterns that are pervasive across animal species. For example, the helicoid motif has gained significant interest in the biomaterials community, where recent studies have highlighted its role in enabling damage tolerance in a diverse set of animals. Moreover, the helicoid motif corresponds to a highly adaptable architecture where the control of the pitch rotation angle between fibrous structures produces large changes in its mechanical response. Nature, takes advantage of this special feature enabling an active response to particular biological needs occurring during an animal's ontogeny. In this work, we demonstrate this adaptive behavior in helicoidal architectures by performing a mechanistic analysis of the changes occurring in the cuticle of the figeater beetle (Cotinis mutabilis) during its life cycle. We complement our investigation of the beetle with the testing of 3D printing samples and a systematic analysis of the effect of pitch angle in the inherent mechanics of helicoidal architectures. Experimentation and analysis reveal improved isotropy and enhanced toughness at lower pitch angles, highlighting the flexibility of the helicoidal architecture. Moreover, trends in stiffness measurements were found to be well‐predicted by laminate theory, suggesting facile mechanics laws for use in biomimicry.

Discontinuous fibrous Bouligand architecture enabling formidable fracture resistance with crack orientation insensitivity

“…Recent investigations revealed that crack twisting mode significantly enhances fracture toughness in the Bouligand architecture where a crack plane propagates following the twisted fiber orientation (27)(28)(29)(30)(31)(32)(33). This amplifies the crack surface area and reorients fibers orientation in response to external loadings (27)(28)(29)33), e.g., tension, bending, or impact loads.…”

Mechanical design of the highly porous cuttlebone: A bioceramic hard buoyancy tank for cuttlefish

“…This is related to the rotating plywood structure found in the septa (SI Appendix, Fig. S6), which has been demonstrated as a microstructure to enhance strength, damage tolerance, and toughness considerably (49)(50)(51). Moreover, the richer organic contents in the septa (8) may also improve the damage resistance (52).…”

Hyperelastic phase-field fracture mechanics modeling of the toughening induced by Bouligand structures in natural materials

“…These chitin-nanofibril-based natural materials are far stiffer and non-deformable compared to elasmoid fish scales (Dastjerdi and Barthelat, 2015;Quan et al, 2018;Yang et al, 2013a;Zimmermann et al, 2013). The Bouligand architecture in this type of material lead to a twisting crack front advance which serves to increase the fracture toughness primarily by crack deflection (Suksangpanya et al, 2017;Suksangpanya et al, 2018;Zaheri et al, 2018); we term these brittle Bouligand structures. Theoretical analyses of such twisted crack trajectories within these Bouligand structures have been proposed (Fischer et al, 2017;Suksangpanya et al, 2017) with the enhanced toughness attributed to the increment in crack-surface area and fracture mode-mixity.…”

“…Theoretical analyses of such twisted crack trajectories within these Bouligand structures have been proposed (Fischer et al, 2017;Suksangpanya et al, 2017) with the enhanced toughness attributed to the increment in crack-surface area and fracture mode-mixity. Recently, through the use of additive manufacturing techniques, fracture mechanisms have also been explored experimentally in fabricated biomimetic Bouligand type materials (Chen et al, 2018;Feilden et al, 2017;Suksangpanya et al, 2018;Yang et al, 2017b;Zaheri et al, 2018). Computational approaches, such as finite element methods with a pre-defined cohesive interface, have also been applied to study the phenomenon of twisted cracks in the brittle form of the Bouligand structure (Suksangpanya et al, 2018).…”