Thank you very much. In this paper, the author has applied a subroutine UMAT for the anisotropic viscoelasticity calculation in Abaqus. But according to you, we can't preform a such calculation directly in Abaqus without subroutine UMAT? Looking forword for your answer. Thank you.
To my knowledge (which is a few years old) there is no anisotropic viscoelastic material model in Abaqus. More than 15 years ago (though) we had to write an UMAT as well.
U can determine the visco-elastic behaviour of anisotropic material in aqueous solution using cone-plate rheometer. This instruments has peltier control so that u can study behaviour at different temperature. Depending on the behaviour of ur material u can feet in different regression model such as newtonian ,non-newtonian, Bhingham and so on available in the software u do not have to go for any calculation you will get calculated values with desired units. For other quantitative calculation you refer book of Polymer science by Bilmeyer
In fact, I'm working on the silicon materials, so I'm not sure if the anisotropic viscoelastic models applied for the polymer materials are still applicabal to my problems. Thank you for your answer.