I am unsuccessfully trying to introduce residual stresses in a hyperelastic anisotropic material characterized by the well-known HGO constitutive model via predefined fields. Any other idea?
Thank you in advance.
There are different ways to specify initial stresses in Abaqus. According to the Abaqus documentation 34.3.1 "Defining initial stresses" the stresses are defined by the keyword *INITIATL CONDITION, TYPE=STRESS. Here you have the following possibilities:
- To define the same stress for all elements
- To import the stresses from an ODB file
- To define stress for each element and integration point using the user subroutine SIGINI (only possible in Abaqus/Standard).
For the last possibility, a file with the initial stresses could be written, which will be read by the user subroutine and written to SIGMA(1..6).
Maybe, this is changed in the meantime. But when I tried last, "*Initial condition, Type = Stress" did not work with hyperelastic anisotropic materials.
An approach to overcome this problem is described e.g. in my 2013 paper " In vivo determination of elastic properties of the human aorta based on 4D ultrasound data" that is publicly available on Researchgate. Basically, the idea consists in identifying the stress free configuration using an iterative inverse Finite Element Model updating approach. Then, in a second step, the solution of the direct boundary value problem (applying the known load to the identified stress-free configuration) provides the deformed and prestressed configuration.
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