#[cfg(test)]
mod test;
use crate::{
constitutive::{
ConstitutiveError,
solid::{Solid, TWO_THIRDS, elastic::Elastic},
},
math::{ContractThirdFourthWithFirstSecond, IDENTITY_00, Quantity, Rank2, TensorRank4},
mechanics::{
Deformation, DeformationGradient, SecondPiolaKirchhoffStress,
SecondPiolaKirchhoffTangentStiffness,
},
units::Stress,
};
#[doc = include_str!("doc.md")]
#[derive(Clone, Debug)]
pub struct Hencky {
pub bulk_modulus: Quantity<Stress>,
pub shear_modulus: Quantity<Stress>,
}
impl Solid for Hencky {
fn bulk_modulus(&self) -> Quantity<Stress> {
self.bulk_modulus
}
fn shear_modulus(&self) -> Quantity<Stress> {
self.shear_modulus
}
}
impl Elastic for Hencky {
#[doc = include_str!("second_piola_kirchhoff_stress.md")]
fn second_piola_kirchhoff_stress(
&self,
deformation_gradient: &DeformationGradient,
) -> Result<SecondPiolaKirchhoffStress, ConstitutiveError> {
let _jacobian = self.jacobian(deformation_gradient)?;
let (deviatoric_strain, strain_trace) = (deformation_gradient
.right_cauchy_green()
.logm()
.map_err(|error| ConstitutiveError::upstream(error, self))?
* 0.5)
.deviatoric_and_trace();
Ok(deviatoric_strain * (2.0 * self.shear_modulus())
+ IDENTITY_00 * (self.bulk_modulus() * strain_trace))
}
#[doc = include_str!("second_piola_kirchhoff_tangent_stiffness.md")]
fn second_piola_kirchhoff_tangent_stiffness(
&self,
deformation_gradient: &DeformationGradient,
) -> Result<SecondPiolaKirchhoffTangentStiffness, ConstitutiveError> {
let _jacobian = self.jacobian(deformation_gradient)?;
let right_cauchy_green = deformation_gradient.right_cauchy_green();
let deformation_gradient_transpose = deformation_gradient.transpose();
let scaled_deformation_gradient_transpose =
&deformation_gradient_transpose * self.shear_modulus();
Ok((right_cauchy_green
.dlogm()
.map_err(|error| ConstitutiveError::upstream(error, self))?
.contract_third_fourth_with_first_second(
&(TensorRank4::dyad_il_jk(&IDENTITY_00, &scaled_deformation_gradient_transpose)
+ TensorRank4::dyad_ik_jl(
&scaled_deformation_gradient_transpose,
&IDENTITY_00,
)),
))
+ (TensorRank4::dyad_ij_kl(
&(IDENTITY_00 * (self.bulk_modulus() - TWO_THIRDS * self.shear_modulus())),
&deformation_gradient_transpose.inverse(),
)))
}
}