Microstructure modeling of random composites with cylindrical inclusions having high volume fraction and broad aspect ratio distribution

Tudryn

Bucinell

et al. 2017

Sci Rep

220

155

We study a unique biomaterial developed from fungal mycelium, the vegetative part and the root structure of fungi. Mycelium has a filamentous network structure with mechanics largely controlled by filament elasticity and branching, and network density. We report the morphological and mechanical characterization of mycelium through an integrated experimental and computational approach. The monotonic mechanical behavior of the mycelium is non-linear both in tension and compression. The material exhibits considerable strain hardening before rupture under tension, it mimics the open cell foam behavior under compression and exhibits hysteresis and the Mullins effect when subjected to cyclic loading. Based on our morphological characterization and experimental observations, we develop and validate a multiscale fiber network-based model for the mycelium which reproduces the tensile and compressive behavior of the material.

Section: Modeling Mycelium Mechanical Behaviormentioning

confidence: 99%

Morphology and mechanics of fungal mycelium

Tudryn

Bucinell

et al. 2017

Sci Rep

220

155

“…Fibrous networks are generated using a fiber packing algorithm described in Ref. [27]. We use the random sequential adsorption technique to generate sparse fiber assemblies and then utilize dynamic finite element simulations to bring the fibers within crosslink-able distance.…”

Section: Modeling and Methodsmentioning

confidence: 99%

Effect of Network Architecture on the Mechanical Behavior of Random Fiber Networks

Journal of Applied Mechanics

Picu

2018

Fiber-based materials are prevalent around us. While microscopically these systems resemble a discrete assembly of randomly interconnected fibers, the network architecture varies from one system to another. To identify the role of the network architecture, we study here cellular and fibrous random networks in tension and compression, and in the context of large strain elasticity. We observe that, compared to cellular networks of same global parameter set, fibrous networks exhibit in tension reduced strain stiffening, reduced fiber alignment, and reduced Poisson's contraction in uniaxial tension. These effects are due to the larger number of kinematic constraints in the form of cross-links per fiber in the fibrous case. The dependence of the small strain modulus on network density is cubic in the fibrous case and quadratic in the cellular case. This difference persists when the number of cross-links per fiber in the fibrous case is rendered equal to that of the cellular case, which indicates that the different scaling is due to the higher structural disorder of the fibrous networks. The behavior of the two network types in compression is similar, although softening induced by fiber buckling and strain localization is less pronounced in the fibrous case. The contribution of transient interfiber contacts is weak in tension and important in compression.

“…This is performed using a dynamic, explicit finite element simulation which packs the fibers in the volume V. The edge size of the unit cell volume is V 1/3 and is at least 3 times larger than L 0 in order to reduce the model size effect. The compacting simulation is performed while enforcing the excluded volume interactions (requirement that fibers do not cross or overlap during system deformation) as implemented in [12]. Inter-fiber cross-links are introduced at locations where the inter-fiber distance is smaller than 2d, where d is the fiber diameter.…”

Section: Models and Simulation Methodsmentioning

confidence: 99%

Random fiber networks with inclusions: the effect of the inclusion stiffness

Picu

2019

Mech Soft Mater

The mechanical behavior of random fiber networks containing inclusions is studied in this work. Inclusions are considered spherical and of radius comparable to the network mean segment length. Their stiffness is varied in a broad range, from very soft to rigid. It is observed that the presence of inclusions modifies the small strain stiffness of the network but does not change the functional form of the non-linear part of the stress-strain curve which, therefore, remains independent of the inclusion stiffness. Soft, bending-dominated networks can be reinforced more efficiently than the stiffer and more affinely deforming axially dominated networks. The variation of the composite modulus with the stiffness of inclusions does not follow the prediction of continuum homogenization theory. Numerical data that allow predicting the homogenized stiffness are presented.