hi all,
both anisotropic invariants I4 and I5 are required to fully describe the material response of transversely isotropic materials. The invariant I4 has a direct interpretation as the square of the stretch in the direction of the fiber but I5 does not have a similar immediate interpretation. if the direction of the fiber is taken to correspond to the E3 coordinate direction then I4 =C33^2, while I5 =C33^2+C13^2+C23^2 and hence I5 is a measure of the influence of shear on the transversely isotropic materials (Cij is component of the right Cauchy–Green tensor)
Are there better interpretation for I5 ??
awaiting to reply
thank you
regards
Davood Taghizadeh