Table 1: Summary and explanation of biomechanical parameters.

Parameter (units)SymbolFormulaLay description of parameter and relevance

Force (N) 𝐹 Nonnormalized force
Undeformed fiber length (m) 𝐿 o Initial knot-knot fiber length
Undeformed diameter (m) 𝑑 o Initial fiber diameter
Undeformed area (m2) 𝐴 o Initial fiber cross-sectional area
Deformed fiber length (m) 𝐿 𝑓 Fiber length following longitudinal deformation
Deformed diameter (m) 𝑑 𝑓 Fiber diameter following longitudinal deformation
Deformed area (m2) 𝐴 𝑓 Fiber cross-sectional area following longitudinal deformation
Longitudinal fiber strain (dimensionless) 𝜀 L ( 𝐿 𝑓 𝐿 o ) / 𝐿 o Normalized longitudinal deformation—percentage fiber extension
Fiber volume 𝑉 𝑓 𝐿 𝑓 𝐴 𝑑 Fiber volume after deformation, assuming a cylindrical geometry
Radial strain (dimensionless) 𝜀 R 𝑑 𝑓 𝑑 o / 𝑑 o Normalized lateral deformation—percentage reduction in fiber diameter following longitudinal deformation; increased radial strain represents stronger coupling between longitudinal and lateral responses.
Cauchy (true) stress (Pa)σ C 𝐹 / 𝐴 𝑑 Force normalized to deformed area—couples force generation to changes in 3D-fiber geometry
LaGrangian stress (Pa)σ LG 𝐹 / 𝐴 o Force normalized to undeformed area—measure of inherent load-bearing ability, decoupled from changes in 3D-fiber geometry
Poisson’s ratio (dimensionless) 𝜈 ( 1 + 𝜀 L ) = ( 1 + 𝜀 L ) 𝜈 Measure of relation between longitudinal strain and radial strain—lateral strain transmission