Is there a best method for simulating a tensile test with a strain rate of 1mm/min that experimentally took minutes while obtaining accurate break results? Is it necessary to run at a specific strain rate like when testing experimentally, or could I run any displacement in any end time and get an accurate stress-strain curve?
Hello, I am attempting to use ANSYS to simulate the tensile testing of a polymer according to ASTM D638. This entails a strain rate of 1mm/min.
I'm having the following issues:
- resources do 1 of the following: a) use explicit dynamics using very fast strain rates eg. displacement = 0.01m, time = 0.001s, or b) they use static structural with a displacement and get a result with no fracture, though it seems much more common in literature.
Following a), my imported material causes an error when break would be expected, where time step goes too small or energy error is too high, but no break happens. Then, if I try to apply the displacement over a long study time, like 1mm/min by applying a displacement and increasing the end time to ~60s, or by applying a velocity of 1mm/min and setting a 60s end time, I get computation times of nearly days and then it fails quite early while saying "energy error too large" or "time step too small".
To reiterate, is there a better, more time-efficient method for performing this? Am I understanding end time and strain rate wrong? Pictures can be added for clarification if requested.
article
https://openscholarship.wustl.edu/cgi/viewcontent.cgi?article=1361&context=eng_etds
said
The default acceptable error in the ANSYS program solver is generally between 0.1 and 0.5% and can vary from step to step within the simulation [25].
Dear Nate Tran ,
It is a bit difficult to understand how you setup your numerical model. I mean you did not say anything regarding how the material is setup (it is setup with Stress-Strain curve or ...) and what nonlinear model is used for this simulation (e.g., Multilinear Kinematic Hardening, Bilinear Kinematic Hardening and etc. ). For that reason I can suggest general guidelines for this type of simulation.
Also, if you haven't considered any fracture concept (e.g., XFEM, etc.) you can't visually see the breakage happening in your model. Therefore, you only see that the analysis is not converged and consequently terminated.
Another important thing is that, you are trying to see the effect of different strain rate in your analysis. If this is the case, then I suggest you use transient structural analysis instead of static structural analysis. Static structural analysis doesn't consider time integration in the numerical analysis and you won't be able to see the effect of different strain rate.
Hope this answer helps!!
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