Question reg ABAQUS-VUMAT and Updated Lagrangian formulation.

Hello all,

I am working on implementing a viscoelastic constitutive model from a hyperelastic stored energy potential (for finite-elasticity) and a dissipation potential (for the viscouls evolution). The elastic constitutive relation, hence derived from the stored energy potential is rate-independent and it is expressed as T(Cauchy's Stress) = f(B), where B is the Left-cauchy green deformation tensor.

The evolution equation is derived out in an objective rate form, which I am integrating over time using a 2nd order accurate explicit method.

My question:

1. How does I let ABAQUS know/(How do I toggle) to use Updated Lagrangian formulation, given that I code my constitutive relation in the format mentioned above?

Thank you.

Srikanth

Research Scholar

Department of Mechanical Engineering

IIT Madras, India.