Learning Forum

[Peter Yip]

Panha,

Bare in mind that effective plastic strain and equivalent plastic strain are different strain measures. Their definitions are very different, but that wasn't too intuitive for me so I will share a slide I put together for a presentation a few months ago. As you can see in the image, the Z-Strain represents the single degree of freedom compression and expansion. The difference is that as you return back to its originally shape via expansion, the effective plastic strain returns to zero and will only accumulate plastic strain as it is expanded beyond it's original shape. However, the equivalent plastic strain continuously accumulates plastic strain even when the element begins expanding by definition since anything beyond yield is considered plastic strain.

So, now you should be equipped to answer why brittle ceramics tend to use effective plastic strain vs other strain measures to quantify damage in their respective simulations. 

All information I have gathered is from online and found here (https://ftp.lstc.com/anonymous/outgoing/support/FAQ/effective_plastic_strain#:~:text=%5BThus%5D%20effective%20plastic%20strain%20and,they%20mean%20the%20same%20thing.&text=Effective%20plastic%20strain%20is%20a,the%20rate%20of%20deformation%20tensor.).