# Tensile test hyperelastic

Member

Hi guys, I'm again! xD

My name is André Moura, i'm try running a hyperelastic simulation. I have the uniaxial test data from experimental test. After some troubles and changes we reach some "good" results.

This is my geometry, 2D.

I got a result of the force close to the experimental by selecting faces A+B (on left) with fixed suport, but when I select only face A, the results are so different (like a half).

On right side I set displacement. After this, Can I simplify my geometry to area left outside those squares?

My main question at the moment is whether this simplification of using only the reduced section is valid.

Do you know if it is possible to access the equations that ansys uses for the simulations?

And, Is it possible to obtain the data of this graph?

thanks a lot.

## Comments

• Member

All material testing is done by taking data over a Gauge Length. That is a portion of the sample where the section is uniform for some distance before and after the Gauge Length.

The wider portions on the ends where the clamps go is always excluded.

The strain that occurs in the Gauge Length is measured by an instrument called an Extensometer. That measurement is now done by a calibrated camera measuring the displacement of dots marking the surface of the specimen.

• Member

Yes, the area 'A' has been excluded, it was the first simplification.

We use a extensometer like this (we have a more old than this) on lab (I have no photo now because lab is closed as the pandemic).

So, can I exclude the 'B' area too?

Thanks a lot

• Member
edited September 15

Yes, exclude the B area from the simulation. But how exactly are you going to do that? You can't just have a fixed support at the cut face. You need to allow the section to get smaller the way it does when you have area B.

Use three planes of symmetry and keep 1/8 of the narrow center section. The face opposite the center plane cut will have a displacement in Y only, leaving X and Z Free (assuming Y is vertical).

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