Models Torque M and load force N expressions Mooney-Rivlin $M=\pi \Psi {a}^{4}\left({C}_{10}+{C}_{01}\right)$ $N=-\pi {\Psi }^{2}{a}^{4}\left(\frac{1}{2}{C}_{10}+{C}_{01}\right)$ Yeoh $M=4\pi \Psi {a}^{4}\left(\frac{1}{4}{C}_{10}+\frac{1}{3}{\Psi }^{2}{a}^{2}{C}_{20}+\frac{3}{8}{\Psi }^{4}{a}^{4}{C}_{30}\right)$ $N=-2\pi {\Psi }^{2}{a}^{4}\left(\frac{1}{4}{C}_{10}+\frac{1}{3}{\Psi }^{2}{a}^{2}{C}_{20}+\frac{3}{8}{\Psi }^{4}{a}^{4}{C}_{30}\right)$ Fung $M=\frac{2\pi C}{{\Psi }^{3}\beta }\left(1-{\mathrm{exp}}^{\beta {\Psi }^{2}{a}^{2}}+{\mathrm{exp}}^{\beta {\Psi }^{2}{a}^{2}}\beta {\Psi }^{2}{a}^{2}\right)$ $N=-\frac{\pi C}{{\Psi }^{2}\beta }\left(1-{\mathrm{exp}}^{\beta {\Psi }^{2}{a}^{2}}+{\mathrm{exp}}^{\beta {\Psi }^{2}{a}^{2}}\beta {\Psi }^{2}{a}^{2}\right)$ Gent-Thomas $M=\frac{\pi }{{\Psi }^{3}}\left(6{K}_{2}\mathrm{ln}\left(3\right)+{a}^{4}{K}_{1}{\Psi }^{4}+2{K}_{2}{a}^{2}{\Psi }^{2}-6{K}_{2}\mathrm{ln}\left({a}^{2}{\Psi }^{2}+3\right)\right)$ $N=-\frac{\pi }{2{\Psi }^{2}}\left(12{K}_{2}\mathrm{ln}\left(3\right)+{a}^{4}{K}_{1}{\Psi }^{4}+4{K}_{2}{a}^{2}{\Psi }^{2}-12{K}_{2}\mathrm{ln}\left({\Psi }^{2}{a}^{2}+3\right)\right)$