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The hyperelastic strain energy function for a Fung Orthotropic material is given by [33, 32] $$\begin{equation} \tilde{\Psi}=\frac{1}{2}c\left(e^{\tilde{Q}}-1\right)+U\left(J\right)\,,\label{eq477} \end{equation}$$ where $$\begin{equation} \tilde{Q}=c^{-1}\sum\limits _{a=1}^{3}\left[2\mu_{a}\mathbf{M}_{a}:\mathbf{\tilde{E}}^{2}+\sum\limits _{b=1}^{3}\lambda_{ab}\left(\mathbf{M}_{a}:\mathbf{\tilde{E}}\right)\left(\mathbf{M}_{b}:\mathbf{\tilde{E}}\right)\right]\,.\label{eq478} \end{equation}$$ Here, $\mathbf{\tilde{E}}=\frac{1}{2}\left(\mathbf{\tilde{C}}-\mathbf{I}\right)$ and $\mathbf{M}_{a}=\mathbf{A}_{a}\otimes\mathbf{A}_{a}$ , where $\mathbf{A}_{a}$ are orthonormal vectors that define the initial direction of material axes. The orthotropic Lamé coefficients should be chosen such that the stiffness matrix, $$\begin{equation} \left[\begin{array}{cccccc} \lambda_{11}+2\mu_{1} & \lambda_{12} & \lambda_{13} & 0 & 0 & 0\\ \lambda_{12} & \lambda_{22}+2\mu_{2} & \lambda_{23} & 0 & 0 & 0\\ \lambda_{13} & \lambda_{23} & \lambda_{33}+2\mu_{3} & 0 & 0 & 0\\ 0 & 0 & 0 & \frac{1}{2}\left(\mu_{1}+\mu_{2}\right) & 0 & 0\\ 0 & 0 & 0 & 0 & \frac{1}{2}\left(\mu_{2}+\mu_{3}\right) & 0\\ 0 & 0 & 0 & 0 & 0 & \frac{1}{2}\left(\mu_{1}+\mu_{3}\right) \end{array}\right]\label{eq479} \end{equation}$$ is positive definite.