FEAP User Forum
FEAP => Input File Issues => Topic started by: sara.grbcic on May 19, 2025, 06:33:31 AM
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Hello,
I am trying to model a hyperelastic membrane problem consisting of a rubber sheet in a simple tension test under large stretch by using the Ogden model integrated in FEAP. To be more precise, I am trying to simulate the numerical solution presented in the book of prof. Ibrahimbegovic - Nonlinear Solid Mechanics, pg. 335, Fig. 4.19. which I am providing in the attachment (DeformedConfigOgdenAIBook.pdf)
When modeling the problem in FEAP, I encounter several problems:
1.) Nodes which are and should be restrained in the definition of the problem, move, (left-hand edge, restrained)
2.) No matter of the choice of the applied loading, or prescribed displacement, on the free (right-hand edge), the configuration deforms only in the lateral direction, while the longitudinal direction remains unaffected (no stretch in the x direction)
I am attaching two versions of my input files and screenshots of the deformed configurations.
Could you please help me with providing an input file which is able to model the deformation presented in DeformedConfigOgdenAIBook.pdf?
I tried adding the mixed formulation, but without any success.
Thanks in advance.
Best regards.
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The main thing you are missing is a PROP to ramp the load in several load steps, there are also some extra commands I have removed. You should always look at the "O" file to see what the analysis did with the commands you provided.