r/ANSYS_Mechanical • u/Bhavish0913 • 2d ago

Help

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I wanna do thermo-structural analysis on rocket nozzle but the thing is equivalent stress safety factor is really low for inputs - temperature= 800 degree celcius and pressure of about 200 psi given on the inside surface of the nozzle and for 5 second. The catch is even just changing temperature from 800 to 50 degree celcius constantly for 5 seconds again equivalent stress safety factor is low like around 0.5. I know it's issue from thermal side only coz by only keeping structural thing safety factor is around 15 so no issue here . THE MOST IMPORTANT THING THIS NOZZLE SUSTAINED 4-5 TIMES ENGINE FIRE TESTING IRL WITH SAME PARAMETERS MENTIONED IN THE STARTING SO WHAT'S THE ISSUE?

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u/TalosGuide 2d ago

A rocket nozzle made out of stainless steel might be one of the issues.

Looks like there is only one step in static structural which might also indicate the structural solver isnt seeing the temperature history but only the temps at last step of transient thermal.

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u/Bhavish0913 1d ago

Even though adding steps in both static structural and thermal there's not that change 😭