Predicting Peak Load in Tension
Predicting Peak Load in Tension
(OP)
This is probably a very simple question but bear with me as I am a beginner with FEA. I have a steel part that I'm applying a simple tensile load to and I'd like FEA to predict the maximum load before fracture. I'm using Autodesk Simulation 2014 with a nonlinear solver. I apply a load, but all I'm seeing is the von mises stress which is good for predicting where the part yields, but does not tell me the peak load that it will take before fracture.
Thanks,
M
Thanks,
M





RE: Predicting Peak Load in Tension
you're using technical terms, probably inappropriately ...
when you say "fracture" i don't think you mean damage tolerance, or stress intensity, but rather static failure, ie the stress on the part = ftu.
now, you know the stress in the part due to the applied load, and you know ftu. the piece that i think you should know is that your FEA is probably linear (ie stress is directly proportional to load).
that should be enough for you to figure it out ...
Quando Omni Flunkus Moritati
RE: Predicting Peak Load in Tension
What material model are you using? Did you verify the model you are using by trying to model a tensile specimen and reproducing its stress-strain curve to failure?
RE: Predicting Peak Load in Tension
Quando Omni Flunkus Moritati
RE: Predicting Peak Load in Tension
Now for my question...I want my model to able to predict the ultimate tensile strength of the sample. If I assume a tensile strength of 66ksi for the material and apply a corresponding load of 4125lbf, the von mises stress shows 77ksi in the material not the expected 66ksi. I'm using the Von Mises Isotropic Hardening plasticity material element, and I'm using a tetrahedryl mesh. Any reason why I cant seem to predict the stress in the material after it has yielded?
RE: Predicting Peak Load in Tension
ftu is a uni-axial stress. von Mises will include the effect of the lateral principal stresses ... look at max principal (rather than vM).
Quando Omni Flunkus Moritati
RE: Predicting Peak Load in Tension
a non linear elasto-plastic analysis can be used and you can monitor plastics strain until they reach the strain that would be at fracture or some other value that is deemed "failure".
the stress vs strain should is often input using true stress and strain for the better solvers.
it is worth noting that the true stress at fracture of a ductile unaxial specimen is often higher than the UTS because of necking and poisson's ratio presenting a smaller cross sectional area for the apllied load. this is why true stress and strain are needed for accurate high plasticity simulations
RE: Predicting Peak Load in Tension
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