Struct KelvinTensor 

pub struct KelvinTensor;

Kelvin (Mandel) notation utilities for symmetric fourth-order tensors.

Unlike Voigt notation, Kelvin notation preserves the inner product: off-diagonal entries are multiplied by √2 for strain-like vectors and √2 for the stiffness off-diagonal blocks, so that C:ε:ε is preserved.

Implementations

impl KelvinTensor

pub fn from_tensor4(c: &Tensor4) -> [[f64; 6]; 6]

Convert a Tensor4 (with minor symmetry) to its 6×6 Kelvin matrix.

K_PQ = w_P * w_Q * C_ijkl where (i,j) is mapped from P and (k,l) from Q.

pub fn to_tensor4(m: &[[f64; 6]; 6]) -> Tensor4

Convert a 6×6 Kelvin matrix back to a Tensor4.

pub fn stress_to_kelvin(t: &Tensor2) -> [f64; 6]

Convert a symmetric second-order tensor to its 6-component Kelvin vector.

Normal components are unchanged; shear components are multiplied by √2.

pub fn kelvin_to_stress(v: &[f64; 6]) -> Tensor2

Convert a Kelvin stress vector back to a Tensor2.

pub fn matvec(m: &[[f64; 6]; 6], v: &[f64; 6]) -> [f64; 6]

Multiply the 6×6 Kelvin stiffness matrix by a Kelvin stress/strain vector.