This package provides the essential building blocks for constitutive hyperelastic material formulations. This includes material behaviour-independent spaces and frameworks as well as material behaviour-dependent model formulations.

Spaces (hyperelastic.spaces) are full or partial deformations on which a given material formulation should be projected to, e.g. to the distortional (part of the deformation) space. Generalized Total-Lagrange Frameworks (hyperelastic.frameworks) for isotropic hyperelastic material formulations based on the invariants of the right Cauchy-Green deformation tensor and the principal stretches enable a clean coding of isotropic material formulations.

The hyperelastic.math-module provides helpers in reduced vector (Voigt) storage for symmetric three-dimensional second-order tensors along with a matrix storage for (at least minor) symmetric three-dimensional fourth-order tensors. Shear terms are not doubled for strain-like tensors, instead all math operations take care of the reduced vector storage.