# Mooney–Rivlin block in Treloar's three modes

One hybrid hex20 unit cube on three symmetry planes, E = 3, ν = 0.49 (μ = 1.006711,
κ = 50), Mooney–Rivlin with C₀₁ = 0.2 (C₁₀ = μ/2 − C₀₁ = 0.303356), in three nonlinear
static steps:

- **Uniaxial**: the face x = 1 pulled to λ = 2, the others free.
- **Equibiaxial**: x = 1 and y = 1 pulled to λ = 1.5, z free.
- **Pure shear**: x = 1 pulled to λ = 2, y = 1 held (λ_y = 1), z free.

The references are the compressible decoupled energy's principal Cauchy stresses
σᵢ = (λᵢ/J) ∂W/∂λᵢ, by differences of W alone, with the free stretch found by bisection so the
free faces carry no stress. The deformation is homogeneous, so the element represents it
exactly.