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Subsubsection 4.1.3.24: Spherical Fiber Distribution from Solid-Bound Molecule Up Subsection 4.1.3: Unconstrained Materials Subsubsection 4.1.3.26: Coupled Transversely Isotropic Veronda-Westmann

#### 4.1.3.25 Coupled Transversely Isotropic Mooney-Rivlin

This material describes a transversely isotropic Mooney-Rivlin material using a fully-coupled formulation. It is define through the coupled trans-iso Mooney-Rivlin material type. The following material parameters must be defined.
 c1 Mooney-Rivlin parameter. [P] c2 Mooney-Rivlin parameter. [P] c3 exponential multiplier [P] c4 fiber scale factor [ ] c5 fiber modulus in linear region [P] lam_max maximum fiber straightening stretch [ ] k bulk-like modulus [P]
The strain-energy function for this constitutive model is defined by The first three terms define the coupled Mooney-Rivlin matrix response. The third term is the fiber response which is a function of the fiber stretch and is defined as in [58]. For , the following form is chosen in FEBio. where is the Jacobian of the deformation.
Example:
<material id="1" type="coupled trans-iso Mooney-Rivlin">
<c1>1</c1>
<c2>0.1</c2>
<c3>1</c3>
<c4>1</c4>
<c5>1.34</c5>
<lam_max>1.3</lam_max>
<k>100</k>
</material>


Subsubsection 4.1.3.24: Spherical Fiber Distribution from Solid-Bound Molecule Up Subsection 4.1.3: Unconstrained Materials Subsubsection 4.1.3.26: Coupled Transversely Isotropic Veronda-Westmann