The principle invariants of the left Cauchy–Green tensor
are calculated as I1 ¼ trð Þ¼ B γ2λ2 þ λ2 þ 2=λ, I2 ¼ 1=2 trð Þ B 2
tr B2 Þ ¼ γ2λ4 þ γ2λ þ 2 λ þ 1=λ2, I3 ¼
B
¼ 1.
Using the left Cauchy-Green deformation tensor, the constitutive
relation for isotropic, homogenous, and incompressible
hyperelastic soft tissue can be written as
σ