Deactivate thermal expansion coefficient at a specific load step

- June 9, 2021 at 9:24 am
  
  ahm.eltaweel
  Subscriber
  
  I am working on an elastomeric O-ring seal analysis at different temperatures in ANSYS Workbench (Mechanical). Generally, I use 4 load steps
  (LS1: stretch O-ring on piston,
  LS2: assembly piston with O-ring in cylinder,
  LS3: cooling from 23°C to -60°C,
  LS4: pressure load).
  I am using a complex visco-hyperelastic material model with WLF-shift function.
  This model of course includes the thermal expansion coefficient too. Now I come to my question:
  Is it possible to deactivate the thermal expansion coefficient for a further 5th load step, as I want to analyze several material effects and here I expect to see such effects without thermal shrinkage when cooling further down to -80°C.
  This means I want to activate the thermal expansion coefficient for LS1-4 and deactivate this coefficient only for LS5 so that the seal is not further showing shrinkage when cooling.”
- June 10, 2021 at 11:45 pm
  
  wrbulat
  Ansys Employee
  
  Hi
  One thing you could try is to create a command object under the body in the tree whose additional thermal strain for -60 < TEMP < -80 is to be unchanged. In this command object you would delete the original thermal coefficient of expansion data (MPDELE,matid,alpx) then replace the TCE with equivalent values of temperature dependent thermal strain using the MPTEMP and MPDATA commands. The material property label for defining thermal strain is THSX (image below). Make the value of THSX the same for -80 C as it is for -60 C. Then calculated thermal strain should not change between these temperatures.
  
  Best Bill