Learning Forum

[Łukasz Ruba]

Hi,

I've created Coupled Field Transient project and I want to import heat generation from a file. When I did it in Thermal Transient it looked like this:

but now i don't see this option:

The file which I use looks like this:

Is it related to the physical area where I only have structural and thermal analyses? I was reading this website: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v231/en/wb_sim/ds_imported_loads.html and see that only Steady-State Thermal, Transient Thermal, Thermal-Electric can import heat generation. Is there any way around this?

Also, I have a question about orthotropic ICTE. I'm not sure if I'm using it correctly. I want to define material conditions that cause the body to expand only when the body temperature is between 80 and 120 degrees Celsius, so I defined it like this:

I was reading this presentation: https://www.padtinc.com/2017/07/11/secant-or-instantaneous-cte-understanding-thermal-expansion-modeling-ansys-mechanical/ and I don't understand why when I define a coefficient of 0 at some temperatures it is wrong. When I use this equation:

it doesn't mean that when coefficient = 0 the strain is 0? I will be very grateful if someone explain it to me. Maybe is there a better way to define exansion only between some temperatures?

 

Best regards,

Lucas

 

[Dave Looman]

Yes, this is a documented limitation: 

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v232/en/wb_sim/ds_coupled_field_limitations.html

Even with the instantaneous coefficient of thermal expansion, the thermal strain will not be zero at a temperature just because the ICTE is zero.  It’s the integral of ICTE from Tzero as you showed in your question.  Also, numerically it’s not ideal to make a large step change in the value.

-Dave

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