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yuanming-hu / taichi_mpm

High-performance moving least squares material point method (MLS-MPM) solver. (ACM Transactions on Graphics, SIGGRAPH 2018)
MIT License
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plasticity #15

Closed iammalekI closed 5 years ago

iammalekI commented 5 years ago

hello In the case of the snow related plasticity, I encountered the problem of 1 - tetac and 1 + tetas because I wanted to see how it was obtained for the soil of these values (although the empirical values do independ on the hydrostatic stress).

yuanming-hu commented 5 years ago

what does "1 - tetac and 1 + tetas" mean?

iammalekI commented 5 years ago

sig[i][i] = clamp(sig[i][i], 1.0f - 2.5e-2f, 1.0f + 7.5e-3f); 1 - tetac=1.0f - 2.5e-2f 1 + tetas =1.0f + 7.5e-3f

yuanming-hu commented 5 years ago

I see. I think those are arbitrary values tuned for visual effects. For engineering applications, you should definitely use a more well-founded constitutive model.

iammalekI commented 5 years ago

relate https://github.com/yuanming-hu/taichi_mpm/blob/master/mls-mpm88-explained.cpp

iammalekI commented 5 years ago

Are computational values accurate or approximate? Example: deformation gradient and velocity.

yuanming-hu commented 5 years ago

They are approximate due to discretization errors...MLS-MPM is first-order accurate.

iammalekI commented 5 years ago

thanks