Struct CartilageModel 

pub struct CartilageModel {
    pub aggregate_modulus: f64,
    pub e_solid: f64,
    pub nu_solid: f64,
    pub permeability: f64,
    pub thickness: f64,
    pub porosity: f64,
    pub fixed_charge_density: f64,
    pub density: f64,
}

Biphasic (solid + fluid) model for articular cartilage.

Based on Mow et al. (1980) biphasic theory:

• Solid phase: linear elastic with Young’s modulus E_s and Poisson’s ratio nu_s.
• Fluid phase: interstitial water with hydraulic permeability k.
• Creep and stress relaxation arise from fluid exudation.

Fields

aggregate_modulus: f64

Solid-phase aggregate modulus H_A = E_s*(1-nu_s)/((1+nu_s)(1-2nu_s)) (Pa).

e_solid: f64

Solid-phase Young’s modulus E_s (Pa). Typical: 0.5–2 MPa.

nu_solid: f64

Solid-phase Poisson’s ratio ν_s.

permeability: f64

Fluid-phase hydraulic permeability k (m⁴/N·s). Typical: ~1e-15 m⁴/N·s.

thickness: f64

Cartilage thickness (m).

porosity: f64

Fluid volume fraction (porosity, 0–1). Typical: 0.65–0.80.

fixed_charge_density: f64

Fixed charge density (mEq/mL) — for swelling pressure computations.

density: f64

Tissue density (kg/m³).

Implementations

impl CartilageModel

pub fn articular_cartilage() -> Self

Typical human articular cartilage (femoral condyle).

Alias for Self::human_knee_cartilage.

pub fn human_knee_cartilage() -> Self

Typical human articular cartilage (femoral condyle).

pub fn compute_aggregate_modulus(e: f64, nu: f64) -> f64

Compute the aggregate modulus from E and ν.

pub fn creep_time_constant(&self) -> f64

Characteristic time constant for creep τ = h²/(H_A * k) (s).

h is the cartilage thickness (m).

pub fn creep_compliance(&self, t: f64) -> f64

Biphasic creep compliance at time t (Pa⁻¹).

Approximation using the first-term series solution from Mow et al. (1980).

pub fn donnan_swelling_pressure(&self, c_ext: f64) -> f64

Donnan osmotic swelling pressure (Pa) at a given NaCl concentration.

c_ext is the external NaCl concentration (mEq/mL).

pub fn darcy_fluid_flux(&self, dp_dz: f64) -> f64

Darcy velocity (fluid flux, m/s) under an applied pressure gradient dp_dz (Pa/m).

pub fn strain_dependent_permeability(&self, e: f64) -> f64

Strain-dependent permeability (Holmes–Mow model).

e is the dilatational strain (volumetric, negative in compression).

Trait Implementations

impl Clone for CartilageModel

fn clone(&self) -> CartilageModel

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CartilageModel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.