Struct CrackBandModel 

pub struct CrackBandModel {
    pub gf: f64,
    pub ft: f64,
    pub young_modulus: f64,
    pub h: f64,
    pub d: f64,
    pub kappa: f64,
}

Crack band model for mesh-objective softening (Bažant & Oh 1983).

Regularizes strain-softening by relating the softening curve to fracture energy G_f and the element characteristic length h. This ensures mesh independence of the energy dissipation.

Fields

gf: f64

Fracture energy G_f (J/m² or N/m).

ft: f64

Tensile strength f_t (Pa).

young_modulus: f64

Young’s modulus E (Pa).

h: f64

Characteristic element length h (m).

d: f64

Current damage variable.

kappa: f64

Maximum historical strain (for irreversibility).

Implementations

impl CrackBandModel

pub fn new(gf: f64, ft: f64, young_modulus: f64, h: f64) -> Self

Create a new crack band model.

The failure strain is computed as ε_f = 2*G_f / (f_t * h).

pub fn initiation_strain(&self) -> f64

Damage initiation strain: ε_0 = f_t / E.

pub fn failure_strain(&self) -> f64

Failure strain: ε_f = 2*G_f / (f_t * h).

This ensures the correct fracture energy is dissipated regardless of element size.

pub fn has_snapback(&self) -> bool

Check snap-back condition: ε_f must be > ε_0.

If h > 2EG_f / f_t², snap-back occurs and the element is too large.

pub fn max_element_size(&self) -> f64

Maximum allowable element size to avoid snap-back.

pub fn update(&mut self, strain: f64)

Update damage based on current strain.

Uses linear softening between ε_0 and ε_f.

pub fn stress(&self, strain: f64) -> f64

Stress for a given strain considering damage.

σ = (1 - D) * E * ε

pub fn dissipated_energy_density(&self) -> f64

Energy dissipated per unit volume so far.

For linear softening: g = 0.5 * f_t * (ε_f - ε_0) * D Total energy dissipated per unit area = g * h ≈ G_f when D=1.

Trait Implementations

impl Clone for CrackBandModel

fn clone(&self) -> CrackBandModel

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CrackBandModel

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

Formats the value using the given formatter.