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This material captures the transversely isotropic behavior of tendon and ligaments while enforcing a large Poisson's ratio. The material utilizes a three part strain energy equation: $$W=W_{\text{fiber}}+W_{\text{matrix}}+W_{\text{vol}}\,,$$ where: $$\begin{aligned}W_{\text{fiber}} & =\frac{1}{2}\frac{c_{1}}{c_{2}}\left(e^{c_{2}\left(\lambda-1\right)^{2}-1}\right)\,,\\ W_{\text{matrix}} & =\frac{\mu}{2}\left(I_{1}-3\right)-\mu\ln\left(\sqrt{I_{3}}\right)\,,\\ W_{\text{vol}} & =\frac{\kappa}{2}\left(\ln\left(\frac{I_{5}-I_{1}I_{4}+I_{2}}{I_{4}^{2(m-v_{0})}e^{-4m\left(\lambda-1\right)}}\right)\right)^{2}\,. \end{aligned}$$ The transversely isotropic strain energy $W_{\text{fiber}}$ takes into account the behavior of the collagen fibers. The isotropic strain energy $W_{\text{matrix}}$ takes into account the mechanical contribution of the extrafibrillar matrix and provides the majority of support when loaded transverse to the fiber direction. The variables $c_{\mathrm{1}}$ , $c_{2}$ and $\mu$ are material parameters controlling the stress-strain response of the material.