Learning Forum

[Dennis Chen]

In a LSDYNA thermal-structural analysis, I am trying to think through if it matters at all if tempearture is in K or in C and if I can set it to Rankine if I wanted? 

To keep unit consistency, is it correct to think that as long as I set every other varaible to have the right unit consistent with the temperature of the problem, it wouldn't matter?  

A prime example is if we have a viscoelastic model with WLF shift function generated from from a reference temperature of 25C in the time-temperature superposition.   In that case, must I keep the temperature unit at C or K?  or is there a way to use rankine if I wanted? 

Appreciate the thoughtful feedback.  

[Ram Gopisetti]

Hi Dennis, 

As you know, LS-DYNA is unitless and relies on a single, consistent set of units applied throughout the entire model setup.

If the WLF parameters are calibrated using a specific unit system (for example, °C) and you intend to use the same system in your model, no correction is required. However, if you plan to use a different unit system (for example, K), the parameters must be converted accordingly and applied consistently with the rest of the model dimensions.

Alternatively, you may use the Solution Explorer to define the model setup. This workflow prompts you to explicitly specify the unit system during setup, which can be more intuitive and help avoid unit‐consistency issues.

Cheers, Ram 

[Dennis Chen]

Hi Ram, thank you very much!