#[cfg(test)]
mod test;
use crate::{
constitutive::{
ConstitutiveError,
solid::{FIVE_THIRDS, Solid, TWO_THIRDS, elastic::Elastic, hyperelastic::Hyperelastic},
},
math::{IDENTITY, Quantity, Rank2, TensorRank4},
mechanics::{CauchyStress, CauchyTangentStiffness, Deformation, DeformationGradient, Scalar},
units::{EnergyDensity, Stress},
};
const FOUR_THIRDS: Scalar = 4.0 / 3.0;
#[doc = include_str!("doc.md")]
#[derive(Clone, Debug)]
pub struct Isihara {
pub bulk_modulus: Quantity<Stress>,
pub shear_modulus: Quantity<Stress>,
pub extra_modulus: Quantity<Stress>,
pub quadratic_modulus: Quantity<Stress>,
}
impl Isihara {
pub fn extra_modulus(&self) -> Quantity<Stress> {
self.extra_modulus
}
pub fn quadratic_modulus(&self) -> Quantity<Stress> {
self.quadratic_modulus
}
}
impl Solid for Isihara {
fn bulk_modulus(&self) -> Quantity<Stress> {
self.bulk_modulus
}
fn shear_modulus(&self) -> Quantity<Stress> {
self.shear_modulus
}
}
impl Elastic for Isihara {
#[doc = include_str!("cauchy_stress.md")]
fn cauchy_stress(
&self,
deformation_gradient: &DeformationGradient,
) -> Result<CauchyStress, ConstitutiveError> {
let jacobian = self.jacobian(deformation_gradient)?;
let isochoric_left_cauchy_green_deformation =
deformation_gradient.left_cauchy_green() / jacobian.powf(TWO_THIRDS);
let first_invariant = isochoric_left_cauchy_green_deformation.trace();
let dw_di1 = 0.5 * (self.shear_modulus() - self.extra_modulus())
+ self.quadratic_modulus() * (first_invariant - 3.0);
Ok(
((isochoric_left_cauchy_green_deformation.deviatoric() * (dw_di1 * 2.0)
- isochoric_left_cauchy_green_deformation
.inverse()
.deviatoric()
* self.extra_modulus())
+ IDENTITY * (self.bulk_modulus() * 0.5 * (jacobian.powi(2) - 1.0)))
/ jacobian,
)
}
#[doc = include_str!("cauchy_tangent_stiffness.md")]
fn cauchy_tangent_stiffness(
&self,
deformation_gradient: &DeformationGradient,
) -> Result<CauchyTangentStiffness, ConstitutiveError> {
let jacobian = self.jacobian(deformation_gradient)?;
let inverse_transpose_deformation_gradient = deformation_gradient.inverse_transpose();
let left_cauchy_green_deformation = deformation_gradient.left_cauchy_green();
let isochoric_left_cauchy_green_deformation =
left_cauchy_green_deformation.clone() / jacobian.powf(TWO_THIRDS);
let first_invariant = isochoric_left_cauchy_green_deformation.trace();
let dw_di1 = 0.5 * (self.shear_modulus() - self.extra_modulus())
+ self.quadratic_modulus() * (first_invariant - 3.0);
let scaled_dw_di1 = dw_di1 * 2.0 / jacobian.powf(FIVE_THIRDS);
let inverse_isochoric_left_cauchy_green_deformation =
isochoric_left_cauchy_green_deformation.inverse();
let deviatoric_inverse_isochoric_left_cauchy_green_deformation =
inverse_isochoric_left_cauchy_green_deformation.deviatoric();
let term_1 = TensorRank4::dyad_ij_kl(
&inverse_isochoric_left_cauchy_green_deformation,
&inverse_transpose_deformation_gradient,
) * TWO_THIRDS
- TensorRank4::dyad_ik_jl(
&inverse_isochoric_left_cauchy_green_deformation,
&inverse_transpose_deformation_gradient,
)
- TensorRank4::dyad_il_jk(
&inverse_transpose_deformation_gradient,
&inverse_isochoric_left_cauchy_green_deformation,
);
let term_3 = TensorRank4::dyad_ij_kl(
&deviatoric_inverse_isochoric_left_cauchy_green_deformation,
&inverse_transpose_deformation_gradient,
);
let term_2 = TensorRank4::dyad_ij_kl(
&IDENTITY,
&((deviatoric_inverse_isochoric_left_cauchy_green_deformation * TWO_THIRDS)
* &inverse_transpose_deformation_gradient),
);
let d_first_invariant_dw_di1_df = deformation_gradient
* (4.0 * self.quadratic_modulus() / jacobian.powf(TWO_THIRDS))
- inverse_transpose_deformation_gradient.clone()
* (FOUR_THIRDS * self.quadratic_modulus() * first_invariant);
let extra_term_1 = TensorRank4::dyad_ij_kl(
&isochoric_left_cauchy_green_deformation.deviatoric(),
&d_first_invariant_dw_di1_df,
) / jacobian;
Ok((TensorRank4::dyad_ik_jl(&IDENTITY, deformation_gradient)
+ TensorRank4::dyad_il_jk(deformation_gradient, &IDENTITY)
- TensorRank4::dyad_ij_kl(&IDENTITY, deformation_gradient) * (TWO_THIRDS))
* scaled_dw_di1
+ TensorRank4::dyad_ij_kl(
&(IDENTITY * (0.5 * self.bulk_modulus() * (jacobian + 1.0 / jacobian))
- left_cauchy_green_deformation.deviatoric() * (scaled_dw_di1 * FIVE_THIRDS)),
&inverse_transpose_deformation_gradient,
)
- (term_1 + term_2 - term_3) * self.extra_modulus() / jacobian
+ extra_term_1)
}
}
impl Hyperelastic for Isihara {
#[doc = include_str!("helmholtz_free_energy_density.md")]
fn helmholtz_free_energy_density(
&self,
deformation_gradient: &DeformationGradient,
) -> Result<Quantity<EnergyDensity>, ConstitutiveError> {
let jacobian = self.jacobian(deformation_gradient)?;
let isochoric_left_cauchy_green_deformation =
deformation_gradient.left_cauchy_green() / jacobian.powf(TWO_THIRDS);
let first_invariant = isochoric_left_cauchy_green_deformation.trace();
let second_invariant = isochoric_left_cauchy_green_deformation.second_invariant();
Ok(0.5
* ((self.shear_modulus() - self.extra_modulus()) * (first_invariant - 3.0)
+ self.extra_modulus() * (second_invariant - 3.0)
+ self.quadratic_modulus() * (first_invariant - 3.0).powi(2)
+ self.bulk_modulus() * (0.5 * (jacobian.powi(2) - 1.0) - jacobian.ln())))
}
}