IBBM 2017

High Stress/Strain Material Behaviors
issueid=580 08-17-2012 08:41 AM
Junior Member
High Stress/Strain Material Behaviors
Large range of stresses within model yield inaccurate material behavior.

I'm running a constitutive model in which a rigid body is attached to the positive x side of a Transversely Isotropic Veronda-Westmann material and pulls this material in the same positive x direction. When I open the file in PostView I notice something strange. From 0 to 50 percent strain the material behaves as one would expect, past the 50 percent mark however, it seems its Poisson's ratio switches somehow because it blows up like a balloon. I have also experienced the same issue when using the transversly isotropic Mooney-Rivlin material. According to Steve this is due to the large range of stresses that I am implementing within the model, and that at especially large stresses the penalty factor (bulk modulus k) is not strong enough to enforce J=1 (the enforcement of constraint.) He also said that a way around this is to use the augmented Lagrangian method, but that currently this method is not working.
Issue Details
Issue Number 580
Project FEBio
Category Unknown
Status Fixed
Priority Unknown
Affected Version Unknown
Fixed Version (none)
Users able to reproduce bug 0
Users unable to reproduce bug 0
Assigned Users (none)
Tags (none)




07-13-2015 10:17 AM
Lead Code Developer
Sorry for the delayed response, but for the record this issue was recently fixed in FEBio 2.3.1.

Steve

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