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Speckled Stress Plots

Question asked by Chris Michalski on Sep 27, 2010
Latest reply on Oct 7, 2019 by Jay Seaglar

I'm relatively new to running SW stress simulations but have been doing CFD simulations for ~6 years.  I recently encountered a bizzarre stress plot resulting from a simple thermal profile.

 

I have a tubular heat exchanger that I have run FloWorks simulations to define the temperature fields.  I had Simulation import that temperature data and calculate the stresses resulting from thermal gradients.  I used the same procedure I have for other models that worked out as expected.

 

I originally included the pressure data but eliminated that because I thought it might be the problem.  In the past similar modesl have come out as expected, low stress in uniform temperature unrestrained areas, higher stress in restrained areas.  The only difference is in the way I defined the fixture points on this model and they are not close to this inlet tube so I don't see how those should have caused this issue.

 

HOWEVER, for some reason this model is generating a speckled stress plot.  Common sense says that in an unrestrained region with a uniform temperature you shouldn't have high tension and high compression intermixed, they will relieve to some middle ground.

 

Anyone ever see anything like this and have an idea how to resolve it?  I have tried altering the mesh parameters, both standard and curvature based, smaller cells down to the point of hours to mesh and days to solve.

 

 

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