Learning Forum

[PureInsanity]

I am trying to figure out how to resolve this error where:

Equivalent creep strain ratio has exceeded the specified limit value. Since the time increment has reached the minimum value, the analysis is stopped.

I have tried other ways to figure this out like change the equivalent ratio to 0 for each step but that led to convergence errors. Can anyone help? I am on a tight deadline.

EDIT: Guess I should have uploaded a pic, I am working on a thermo-mechanical buckling project of this plate with 0.1" thickness where the two ends are fixed and I applied a tabular-controlled temperature, while measuring the reaction force at one end. The error I am getting right now according to the Solver Output is "Error in Element Formulation."

 

[Sandeep Medikonda]

Hi,

The typical suggestion is to try running the model without the creep first: since you are solving buckling that alone can pose element formulation errors. The creep strain limit option appears under Analysis Settings > Creep and that can be adjusted. But often, the issue is elsewhere and the default value should be just fine except for very specific cases.

[Sandeep Medikonda]

Also, one another suggestion you can try is to look at the magnitude of the elastic strain and try to assess what is an expected creep strain per increment (by hand). From there, you can arrive at a reasonable max allowable ratio (= creep strain/elastic strain).

[PureInsanity]

I have tried both running without the creep and the max ratio. I do not have any error relating to the creep/strain ratio  anymore, but I am still getting the "error in element formulation." It lead to a lot of sudden distortions as I am running the program, even according to the solver output.

One boundary condition I did not mention was the initial perturbation of 0.7 mm that lasts no longer than a second. In addition, the mesh I currently have is 0.5 inches. Do you think it has anything to do with the boundary conditions or the mesh?

 

[Bhargava Sista]

Hi,

I'd suggest that you first get the model to run without using creep. Buckling can be challenging by itself if you're doing a nonlinear buckling analysis instead of linear eigenvalue analysis. Can you please provide more details about your model such as type of analysis (static or transient), loads and boundary conditions, an image of mesh density, and time-stepping (if applicable)? It'd be helpful in providing a better solution.