Learning Forum

[uiluj]

Dear cmmunity, 

im trying to reacreate a tensile test in ansys to validate a voce-swift-hardening model. The result of the real life tensile test is plotted in the excel sheet as the oragne curve and the ansys result is plotted as the blue curve.

As you can see, there is a part of the strain stress curve that is constant in the ansys result. I need some help in finding the reason for this. I used the static structural component for this with mulitlinear kinematic hardening. 

kind regards, 

Sebastian

 

[Armin]

Hi Sebastian,

Could you describe how you defined the hardening curve (stress versus plastic strain) in the Engineering Data? If you don't expect reverse loading to activate kinematic hardening effects, I would suggest that you employ "Multilinear Isotropic Hardening" instead. 

[uiluj]

Hi Armin,

this is how i definded the hardening curve. I got the variables for the voce-swift-function from a curve fitting script and calculated the stress values with them. 

[Armin]

Thanks Sebastian. To my opinion, you need to input more data points in the small strain region. Check how the stress jumps from ~427 MPa to ~827 MPa from zero to 0.02 strain. You need to add more intermediate values in this range otherwise Ansys Mechanical software will linearly interpolate your data. This may explain the discrepancy in validating your simulation against experimental data (in your first post) that shows up as a linear curve in the small strain regime. 

[uiluj]

Thank you very much, that was actually the problem.