Mechanics of bioinspired fibrous material – BioFibMat
Mechanics of bioinspired fibrous material
The project explores how the organization of fibrous materials controls their shape and mechanical strength. Inspired by biological structures, it enables the design of flexible, adaptive materials capable of deploying, reinforcing, or changing shape, with applications in soft robotics and smart materials.
Fibrous materials are ubiquitous in living systems and exhibit remarkable mechanical properties that arise from their organization rather than the intrinsic nature of their constituents. These systems are paradigmatic examples of flexible mechanical metamaterials, whose response is governed by geometry, connectivity, and interactions between fibers. Recent studies in metamaterials have shown that unconventional mechanical behaviors can be achieved, but their translation to disordered or bio-inspired fibrous systems remains limited and poorly understood. The project aims to bridge the gap between biological observation, physical modeling, and the design of fibrous metamaterials, using controlled experiments and model systems. More specifically, the project seeks to: (i) Identify the physical mechanisms governing the mechanical response of assemblies of frictional fibers under tension, compression, and deployment transitions, with particular attention to nonlinear effects and the role of connectivity and fiber–fiber friction. (ii) Understand the role of fibrous reinforcements in biological structures and their contribution to the overall mechanical response. This includes analyzing dynamic and deployable processes, such as insect wing deployment, to identify robust mechanical principles from nature that can be translated into artificial systems. (iii) Design and characterize fibrous metamaterials capable of programming three-dimensional shapes and specific mechanical responses. In particular, the project explores architectures incorporating elastoplastic fibers, enabling the permanent or reversible encoding of shape and mechanical properties, paving the way for morpho-programmable materials with potential applications in minimally invasive surgery. A transversal objective is to establish constitutive laws linking structural organization, local interactions (contacts, friction, plasticity), and macroscopic response. The project thus proposes generic design principles for robust, adaptive bio-inspired materials. It has enabled the emergence of a new class of flexible mechanical metamaterials, in which functionality and the programmed mechanical response rely on the collective organization and arrangement of fibers rather than the intrinsic complexity of the constituent materials.
The project is based on an integrated approach combining controlled experiments, biological observations, and theoretical and numerical modeling, in order to connect microscopic mechanisms to the macroscopic properties of fibrous materials. This multi-scale approach enables the establishment of effective constitutive laws and guides the design of bio-inspired fibrous metamaterials.
The project has yielded several key results, both on the fundamental side and for the design of bio-inspired materials:
(i) Fibrous assemblies as metamaterials. Experiments on fiber bundles subjected to tension and compression demonstrated that they behave as flexible mechanical metamaterials. Macroscopic properties emerge directly from the collective organization (connectivity, density, anisotropy, orientation), rather than the individual properties of the fibers. Coupled measurements of mechanical response and structural evolution identified key mechanisms, including fiber reorientation, the role of friction, and topological rearrangements. These findings pave the way for new effective descriptions of disordered fibrous media.
(ii) Role of fibrous reinforcements in biological deployment. The study of Drosophila wing deployment highlighted the critical role of fiber architecture in controlling kinematics and robustness. By combining experiments, imaging, and modeling, we identified the existence of a mechanical operating point that enables rapid and robust deployment. These results provide new insights into deployment mechanisms in biological structures, showing how global properties emerge from internal organization.
(iii) Design of morpho-plastic metamaterials. We developed a new class of cellular structures composed of elastoplastic fibers, capable of generating complex three-dimensional shapes and programming their mechanical response. These morpho-plastic metamaterials allow controlled encoding of shape states and mechanical properties by exploiting irreversible deformations at the fiber scale. They demonstrate the possibility of designing materials whose functionality relies on internal architecture, with potential applications in deployable structures.
(iv) Interactions with the environment. We characterized the behavior of fibrous structures interacting with complex environments, including viscous fluids and frictional granular media. The results show how these interactions influence reorganization, mobility, and energy dissipation in fibrous networks, with implications for both biological systems and penetration into granular media.
The project opens new perspectives for the design of flexible and adaptive mechanical materials inspired by living systems. The results provide design principles for programmable metamaterials, with potential applications in soft robotics, deployable structures, and smart materials.
Beyond applications, the project contributes to a better understanding of fibrous biological systems and the physical mechanisms governing their behavior. It also strengthens the links between mechanics, materials physics, and bio-inspiration, providing a unified framework for the study of fibrous assemblies.
The research objective of this proposal is to rationalize the mechanics of assemblies of passive flexible frictional fibers and to prototype functional fibrous materials that deploy and react to an external stimulus. Passive fibers like pine needles are known to create aggregate that can be shaped in complex form when compressed. One striking difference between fibers and other granular materials is the effective cohesion of their assembly. We will first describe how the interplay between bending of the fibers and frictional interaction dominates the mechanics of the assembly for passive fibers. In a second step, we will study the dynamics of the packing when the fibers are active and change shape, a strategy used in some plants to perform motion and eject their seeds. We will study two plant systems where the organization of active fibers leads to two radically different dynamics and transfer those strategies to design new materials with tailored mechanical and dynamic properties.
Project coordination
Joel Marthelot (Institut universitaire des systèmes thermiques industriels)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partnership
IUSTI Institut universitaire des systèmes thermiques industriels
Help of the ANR 268,593 euros
Beginning and duration of the scientific project:
October 2021
- 48 Months
