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Help needed in defining Creep for geomaterials

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satyasrinivas

Structural
Jan 18, 2008
67
Hi

I have been trying to model power law creep is abaqus using the standard time-law hardening option. The following are the values I am using:

Youngs Modulus = 55e12, Poisson's ratio = 0.25
A = 2.9e-37, n = 3.3, m = 0. (My model length unit is in Kms (not meters); hence the unusual numbers for the constants). Total step time = 1.0.

Now when I run the analysis for 10 % total extension, I get deviatoric stresses up to 6 GPa - The problem is, this is unrealistically high for long-term strength in rocks (usually in the range of 200 MPa).

My question is - Am I defining all the parameters in defining secondary creep or am I missing something ?

Secondly, the elastic component of stresses is way too prominent in my model. How to reduce the elasticity and introduce creep effects at earlier (at very low strains) ? Any suggestions.

Thanks
SS
 
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