# How KT is calculated in CundallStrack Contact Model

HI,

I am new to Yade.

I am using CundallStrack contact Law. In the documentation it is mentioned that Kt is the ratio of Kn and the ratio is calibrated to match the macroscopic poisson's ratio. Is there any specific formula to calculate the Kt value.

Thanks.

Daka

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- Last query:
- 2021-02-19

- Last reply:
- 2021-02-19

Jan Stránský (honzik) said : | #1 |

Hello,

> I am new to Yade.

welcome :-)

> Is there any specific formula to calculate the Kt value.

No :-(

As the documentation says, set the value such that the macroscopic response of your sample match the desired value.

A few tests for different values should tell you the basic trend. You can try some extreme values, e.g. 0 and 100, then a few "normal" values, like 0.1, 0.2, 0.5.

The actual trend (and "a specific formula to calculate the Kt value") would be different for different geometry - particle size distribution, packing density (dense/loose), actual packing (structured/

cheers

Jan

Trishala DAKA (saidaka) said : | #2 |

Thank you Jan

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