#[cfg(test)]
mod test;
use crate::{
constitutive::{
ConstitutiveError,
solid::{Solid, TWO_THIRDS, elastic::Elastic},
},
math::{ContractThirdFourthWithFirstSecond, IDENTITY, Quantity, Rank2, Spectrum, TensorRank4},
mechanics::{CauchyStress, CauchyTangentStiffness, Deformation, DeformationGradient, Scalar},
units::Stress,
};
#[doc = include_str!("doc.md")]
#[derive(Clone, Debug)]
pub struct SethHillEulerian {
pub bulk_modulus: Quantity<Stress>,
pub shear_modulus: Quantity<Stress>,
pub exponent: Scalar,
}
impl SethHillEulerian {
pub fn exponent(&self) -> Scalar {
self.exponent
}
}
impl Solid for SethHillEulerian {
fn bulk_modulus(&self) -> Quantity<Stress> {
self.bulk_modulus
}
fn shear_modulus(&self) -> Quantity<Stress> {
self.shear_modulus
}
}
impl Elastic for SethHillEulerian {
#[doc = include_str!("cauchy_stress.md")]
fn cauchy_stress(
&self,
deformation_gradient: &DeformationGradient,
) -> Result<CauchyStress, ConstitutiveError> {
let jacobian = self.jacobian(deformation_gradient)?;
let left_cauchy_green = deformation_gradient.left_cauchy_green();
let (deviatoric_strain, strain_trace) = if self.exponent() == 0.0 {
(left_cauchy_green
.logm()
.map_err(|error| ConstitutiveError::upstream(error, self))?
* 0.5)
.deviatoric_and_trace()
} else {
((left_cauchy_green
.powm(0.5 * self.exponent())
.map_err(|error| ConstitutiveError::upstream(error, self))?
- IDENTITY)
/ self.exponent())
.deviatoric_and_trace()
};
Ok(deviatoric_strain * (2.0 * self.shear_modulus() / jacobian)
+ IDENTITY * (self.bulk_modulus() * strain_trace / 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 left_cauchy_green = deformation_gradient.left_cauchy_green();
let inverse_transpose_deformation_gradient = deformation_gradient.inverse_transpose();
if self.exponent() == 0.0 {
let (deviatoric_strain, strain_trace) = (left_cauchy_green
.logm()
.map_err(|error| ConstitutiveError::upstream(error, self))?
* 0.5)
.deviatoric_and_trace();
let scaled_deformation_gradient =
deformation_gradient * (self.shear_modulus() / jacobian);
return Ok((left_cauchy_green
.dlogm()
.map_err(|error| ConstitutiveError::upstream(error, self))?
.contract_third_fourth_with_first_second(
&(TensorRank4::dyad_il_jk(&scaled_deformation_gradient, &IDENTITY)
+ TensorRank4::dyad_ik_jl(&IDENTITY, &scaled_deformation_gradient)),
))
+ TensorRank4::dyad_ij_kl(
&(IDENTITY
* ((self.bulk_modulus() - TWO_THIRDS * self.shear_modulus()) / jacobian)
- deviatoric_strain * (2.0 * self.shear_modulus() / jacobian)
- IDENTITY * (self.bulk_modulus() * strain_trace / jacobian)),
&inverse_transpose_deformation_gradient,
));
}
let half_exponent = 0.5 * self.exponent();
let spectrum = Spectrum::new(&left_cauchy_green)
.map_err(|error| ConstitutiveError::upstream(error, self))?;
let (deviatoric_strain, strain_trace) = ((spectrum
.powm(half_exponent)
.map_err(|error| ConstitutiveError::upstream(error, self))?
- IDENTITY)
/ self.exponent())
.deviatoric_and_trace();
let cauchy_stress = deviatoric_strain * (2.0 * self.shear_modulus() / jacobian)
+ IDENTITY * (self.bulk_modulus() * strain_trace / jacobian);
let scaled_deformation_gradient =
deformation_gradient * (2.0 * self.shear_modulus() / (self.exponent() * jacobian));
let trace_term = spectrum
.powm(half_exponent - 1.0)
.map_err(|error| ConstitutiveError::upstream(error, self))?
* deformation_gradient;
Ok(spectrum
.dpowm(half_exponent)
.map_err(|error| ConstitutiveError::upstream(error, self))?
.contract_third_fourth_with_first_second(
&(TensorRank4::dyad_il_jk(&scaled_deformation_gradient, &IDENTITY)
+ TensorRank4::dyad_ik_jl(&IDENTITY, &scaled_deformation_gradient)),
)
+ TensorRank4::dyad_ij_kl(
&(IDENTITY
* ((self.bulk_modulus() - TWO_THIRDS * self.shear_modulus()) / jacobian)),
&trace_term,
)
- TensorRank4::dyad_ij_kl(&cauchy_stress, &inverse_transpose_deformation_gradient))
}
}