Learning Forum

[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 ?