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[Factoo,Anjum]

Hello Friends,

I am solving a case, where I want to cycle the thermal loads 3 times(Hot to Ambient to Hot …so on), Like start-up shutdown scenario. I am using a NL material (BKIN) model to see accumulation of plastic strains at the end of these cycles. I am starting with 2 load step approach in ANSYS simulating 1 full cycle. If this works, I will cycle it as many times as I want.

Now, I have a steady state thermal result which captures the hot condition ( The components are majorly in 400 deg C range .. but a small region is experiencing about 900 deg C). I am importing this load into my static structural at step1 as HOT CONDITION. 

Now for step 2 (COLD CONDITON), which is when the whole system cools down to ambient condition (25 deg C). I don’t have any steady state solution for this because the whole assembly is at 25 deg C. So, I am applying a direct temperature BC (25deg C) at step 2 on the full assembly. 

Please note, I am deactivating the imported temperature in Step2 and similarly the deactivating temperature BC (25 deg C) in step 1. 

Now the load step 1 solves very smoothly. But when the solution enters LS 2, I am getting as element distortion ERROR and solution stops. I checked the last saves solution and the elements in the 900deg C region are getting highly distorted probably because the temp. is jumping from 900 deg C to 25 degC. I am already using very small sub-steps. 

Does anyone in the here have any better ideas how I can Solve this problem. Is there anything which I am missing ?

[Sai Deogekar]

Hi,

Maybe you can try altering the Mesh settings: set Physics Preference: Nonlinear Mechanical and Element order to Linear. 

If this doesn't work, maybe you can try using Nonlinear Adaptive Meshing (NLAD) and see if that helps to resolve this error.

Here is a video that might help: How to Handle Element Distortion Errors in Hyperelastic Materials — Lesson 3 | ANSYS Innovation Courses You are already using small substeps and since you are using a plasticity model, I am hoping that the material definition is not an issue. So I would try out the other options mentioned in the video.