## Abstract

Principal axis formulations are regularly used in isotropic elasticity, but they are not often used in dealing with anisotropic problems. In this paper, based on a principal axis technique, we develop a physical invariant orthotropic constitutive equation for incompressible solids, where it contains only a one variable (general) function. The corresponding strain energy function depends on six invariants that have immediate physical interpretation. These invariants are useful in facilitating an experiment to obtain a specific constitutive equation for a particular type of materials. The explicit appearance of the classical ground-state constants in the constitutive equation simplifies the calculation for their admissible values. A specific constitutive model is proposed for passive myocardium, and the model fits reasonably well with existing simple shear and biaxial experimental data. It is also able to predict a set of data from a simple shear experiment.

Original language | British English |
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Pages (from-to) | 215-223 |

Number of pages | 9 |

Journal | Biomechanics and Modeling in Mechanobiology |

Volume | 12 |

Issue number | 2 |

DOIs | |

State | Published - Apr 2013 |

## Keywords

- Incompressible
- Invariants with immediate physical meaning
- Myocardium
- Orthotropic
- Principal axes
- Strain energy