When structure does not imply symmetry

TL;DR

This study investigates whether microstructural anisotropy in fungi-based materials leads to macroscopic mechanical and sensory anisotropy, revealing that microstructure does not always imply anisotropic behavior.

Contribution

The paper introduces a data-driven framework to infer symmetry in complex soft materials, challenging the assumption that microstructural anisotropy always results in anisotropic mechanics.

Findings

Fungi-based materials show a range of symmetry classes from anisotropic to isotropic.

Fiber-dependent invariants are only relevant when mechanically significant.

Microstructural anisotropy does not necessarily lead to anisotropic mechanical or sensory properties.

Abstract

Fungal protein materials exhibit inherently anisotropic microstructures formed by networks of hyphae, which suggest a natural pathway to replicate the fibrous texture of animal meat. We probe whether this structural anisotropy translates into macroscopic mechanical and sensory anisotropy. Using orthogonal tension, compression, and shear experiments on three fungi-based materials, we identify distinct symmetry classes that range from strongly anisotropic to effectively isotropic behavior. Automated model discovery reveals that fiber-dependent invariants emerge only when mechanically relevant, and enables direct identification of material symmetry from data. These results demonstrate that microstructural anisotropy does not universally imply anisotropic mechanics or perception and establish a data-driven framework to infer symmetry in complex soft materials.