Bioinspiration: failure and damage identification in natural nacre and translation to synthetic composites or biohybrid materials

Abstract

Many materials found in nature are comprised of relatively weak materials, yet they still exhibit superior mechanical performance. This performance originates within elegant hierarchical structures. Nacre exhibits remarkable strength and toughness despite its composition of greater than 95% aragonite, a brittle ceramic. By incorporating just 5% soft biopolymer into a hierarchical structure with the brittle ceramic, nacre is ~1000 times tougher than pure aragonite. This significant increase in toughness stems from toughening mechanisms that act at multiple length scales within the hierarchical structure. A better knowledge of these mechanisms is at sake in material science because they can be directly translated to synthetic materials - biomimicry approach - or we can also directly incorporate these natural materials into synthetic materials to create hybrid biomaterials.

People

Current people in the group:

Ana Cláudia Pinto Dabés Guimarães
PhD student
Use of sea-shells for environmental-friendly concretes

(PhD defense in 2022)

Alumni

Elvis Baffoe
MSc student
On the evaluation of Oyster and Nacre as high performance cement-based grouts for geothermal well cementation

(MSc defense 15-07-2019)Now: PhD studentUniv. Miami, USA

Connected publications

Identification of deformation mechanism in abalone shells through AFM and digital image correlationIn contrast to man-made materials, nature can produce materials with remarkable mechanical properties from relatively weak constituents. Nacre from seashells is a compelling example: despite being comprised mostly of a fragile ceramic (polygonal calcium carbonate tablets), it exhibits surprisingly high levels of strength and toughness. This performance is the result of an elegant hierarchical microstructure containing a small volume fraction of biopolymers at interfaces. The product is a composite material that is stiff and hard yet surprisingly tough, an essential requirement to protect the seashell from predators. Building a comprehensive understanding of the multi-scale mechanisms that enable this performance represents a critical step toward realizing strong and tough bio-inspired materials. This paper details a nanoscale experimental investigation into the toughening mechanisms in natural nacre and presents a way to translate this understanding to the design of new bioinspired composites. In situ three point bending fracture tests are performed to identify and quantify the toughening mechanisms involved during the fracture of natural nacre at the nanoscale. At the macro and micro scales, previous fracture tests [1] and [2] performed in situ enabled observation of spreading of damage outward from the crack tip. In this study, fracture tests are performed in situ an atomic force microscope to link the larger-scale damage spreading to sliding within the tablet-based microstructure. To quantify the magnitude of sliding and its distribution, images from the in situ AFM fracture tests are analyzed using standard and new algorithms based on digital image correlation techniques which allow for discontinuous displacement fields. Ultimately, this comprehensive methodology provides a framework for broad experimental investigations into the failure mechanisms of bio- and bio-inspired materials.
In-situ AFM Experiments with Discontinuous DIC Applied to Damage Identification in BiomaterialsNatural materials (e.g. nacre, bone, and spider silk) exhibit unique and outstanding mechanical properties. This performance is due to highly evolved hierarchical designs. Building a comprehensive understanding of the multi-scale mechanisms that enable this performance represents a critical step toward realizing strong and tough bio-inspired materials. This paper details a multi-scale experimental investigation into the toughening mechanisms in natural nacre. By applying extended digital image correlation and other image processing techniques, quantitative information is extracted from otherwise prodominantly qualitative experiments. In situ three point bending fracture tests are performed to identify and quantify the toughening mechanisms involved during the fracture of natural nacre across multiple length scales. At the macro and micro scales, fracture tests performed in situ with a macro lens and optical microscope enable observation of spreading of damage outward from the crack tip. This spreading is quantified using an iso-contour technique to assess material toughness. At the nanoscale, fracture tests are performed in situ an atomic force microscope to link the larger-scale damage spreading to sliding within the tablet-based microstructure. To quantify the magnitude of sliding and its distribution, images from the in situ AFM fracture tests are analyzed using new algorithms based on digital image correlation techniques which allow for discontinuous displacement fields. Ultimately, this comprehensive methodology provides a framework for broad experimental investigations into the failure mechanisms of bio- and bio-inspired materials.


Connected projects

Newpores - New Frontiers in Porous Materials

Granted by E2S UPPA, NewPores is an international hub dedicated to the mechanics and physics of porous materials, which intends to answer to new Energy and Environment challenges. This is a joint effort of the group on Geomechanics and Porous Materials (G2MP) of the Laboratoire des Fluides Complexes et leurs Réservoirs at E2S UPPA (France), the Centre for Sustainable Engineering of Geological and Infrastructure Materials (SEGIM) at Northwestern University (USA), the University of Vigo (Spain), the Technical University of Madrid (Spain) and University of Liège (Belgium).

BeCCoH - BÉton et Coulis pour la valorisation de COquilles d’Huîtres (BeCCoH)
OSTRA - Valorisation de coquilles d’huîtres dans des bétons à faible impact environnemental

Financé par la région Nouvelle-Aquitaine et la Communauté d'Agglomération Pays Basque, les projets BeCCoH et OSTRA visent à valoriser les déchets et coproduits coquillers, notamment produits sur le bassin sud d’Arcachon, dans des matériaux cimentaires tels que des bétons ou des coulis de ciment. Ils sont basé sur l’approche performantielle, une démarche innovante permettant de valider des bétons pour des applications spécifiques lorsque la norme NF EN 206-1, qui encadre la production de béton de construction en France, ne s’applique pas.

NacreWell - On the evaluation of Oyster and Nacre as high performance cement-based grouts for geothermal well cementation

Well cementation is used to mechanically link tubing to geological formation and it performs a crucial role to avoid mass transfers between the different geological layers during production. Considering the critical role cement grouts play in order to achieve a well integrity, there is the need to provide an ideal cement grout, which possesses high strength but low ductility and density, which can not be achieved by the classical synthetic materials. Some natural materials like oyster and nacre possess super mechanical performance that may help improve the performance of the grout. This project aims at incorporating oyster or nacre in cements grout formulation in order to increase their performance and decrease their environmental impact.