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Hyperelastic modelling for soft biological tissues

Hyperelastic modelling for soft biological tissues

Hyperelastic modelling for soft biological tissues

(OP)
Hi All,

I'm doing an ABAQUS analysis on soft biological tissues such as liver or kidney undergoing compression. The purpose of this project to find out the mechanical properties of the tissues interaction to different set loads, boundary condition etc. This would provide virtual surgical training for the medical field.

One of my colleague is doing the unaxial compression experiment while i will be doing the finite element analysis under going compression load using ABAQUS.

As i was not trained in ABAQUS before, i simply went through various tutorials and help file available online. (Either from ABAQUS or some random slides).

The steps for modelling ( In my context )

Part- I drew the desired the liver part that i want to model (2D)
Material - Define my hyper-elastic material model such as Ogden. Density of tissues etc. Did a material evaluation to find out the model suitability to the data etc.
Sections - Define section and assign section to my defined material.
Steps - Define my step configuration. Static general. Pressure. etc
Load - Define compression load.
BC - define boundary condition to be set in unconfined compression.
Mesh - Assign element control, type and seed the part accordinly before i mesh it.
Job - Create job and submit for analysis.

I have problem with
the step module (timing ) what would be suitable in such a model?
the Boundary condition - What boundary should be set in a unconfined compression?
MESH - as the model has a hyperelastic behaviour, ABAQUS has prompted me to use hybrid element however, i could not assign the element type i want to the model. Whenever i try clicking mesh element, the dialog pops up instead of letting me choose the region to be assigned first.

Appreciate if anyone out there can help me with this or share their experiences with me.
Thank you

 

RE: Hyperelastic modelling for soft biological tissues

a) In a general static step, "time" is simply numerical time to apply the load in small increments and ensure equilibrium.
b) Same boundary conditions as in the physical experiment. I'd imagine one end must've been fixed and the other end must've been used to apply compression loading. [You may need frictionless sliding interaction between the loading surface and the tissue surface as well.]
c) I am not sure. What element type did you assign in the first place? You'll definitely need hybrid elements since tissue deformations are "high".

http://www.eng-tips.com/faqs.cfm?fid=376
http://www.eng-tips.com/faqs.cfm?fid=1083

RE: Hyperelastic modelling for soft biological tissues

(OP)
Hi Icebreaker!

Thank you..

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