Learning Forum

[Iñigo Ugarte]

Im trying to define an hyperelastic material using uniaxial tension, uniaxial compression and simple shear tests' data. I add the data to a new material, but when implementing the hyperelastic model (Ogden 3) it doesn't take the shear data i provided, as the model's curve fitting asks for uniaxial, biaxial, shear (I´m guessing it´s pure shear) and volumetric, but not for simple shear. 

Can I change the test data the curve fitting is asking for? 

Is there a way to automatically convert the data or do i have to do it manually before adding it to the material? If so, why would there be an option for entering simple shear test data in the first place?

Thanks in advance

[John Doyle]

If you want to curve fit the ogden model, you should enter your uniaxial tension data as 'Uniaxial Test Data'.  You should convert uniaxial compression data to 'Biaxial Test Data'.  The Shear Test Data should be planar shear, not simple.

Uniaxial Tension, Uniaxial Compression and Simple Shear data are typically used directly with the Response Function (not curve fitting the hyperelastic strain energy density functions).

Refer also to Chapters 4 and 6 of the MAPDL Material Reference Manual for more details on preparing test data for curve fitting hyperelastic models.