Hardening Soil Model - Typicial relationships between E50, Eur, and Eoed

Question

Dear all, 
 Sometimes, when I am using the Hardening Soil model I receive an error message similar to the following one: 
 
 I assume that the program does an internal check accoding to usual models to know if the input values are realistic or not. 
 Where can I find these internal checks? 
 Kind regards and thank you in advance, 
 Alexandra

Stefanos Papavasileiou · Answer

Dear Alexandra, I believe that you have been assisted in a service request, but here is the information for the general knowledge of the forum: During the validation of the material set, when you try to save (by clicking OK), an iterative algorithm is used to check if all parameters fit within the Hardening Soil formulation by trying to fit the parameters M and alpha (see section On the cap yield surface in the Hardening Soil Model , Material Models manual). There are some basic criteria that must be met even before the iteration-test is performed: E 50,ref < E ur,ref / 2 E ur,ref > E oed,ref E ur,ref < 20 * E 50,ref E oed,ref > 0.1 * E 50,ref Based on the validation check of the parameters (the basic checks and the iterative validation), a restriction will be given for why the parameters do not fit within the model. These parameters can include any of the stiffness and strength parameters. If this given restriction is met by changing the mentioned parameter, the validation may continue and check other parameters, until all criteria are met. This could mean that you (or the program) needs to update the parameters more than one time. Therefore, it is not so easy to say why a parameter it not correct for the Hardening Soil model. E.g. based on the other parameters, some standard correlations may not work, like K0NC = 1 - sin(phi).

Paras Khaitan · Answer

This is in Material's Model Article 6.4.3 
 The simplest way out is either calculate K0 by the formula in this paragraph and include in the "Advanced" section, or there's a Default values check box which can help you plugin just E value and update the remaining Parameters automatically.

Hardening Soil Model - Typicial relationships between E50, Eur, and Eoed

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