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Re: [Question #681383]: problem of the unit of normal force in Law2_PolyhedraGeom_PolyhedraPhys_Volumetric


Question #681383 on Yade changed:

Jan Stránský proposed the following answer:

> normal force between two polyhedra is calculated by:

only using Law2_PolyhedraGeom_PolyhedraPhys_Volumetric :-)

> while kn is calculated by:
> contactPhysics->kn = Kna*Knb/(Kna+Knb)
> the problem is that the unit of kn is Pa ...

Kna*Knb/(Kna+Knb) is just a (half of) harmonic average of two values. It
says nothing about physical units.

> when it multipy with volume, with unit of m³, then the unit of normal
force become N.m,but it suppose to be N.

kn is multiplied by 'prop'. It is penetrationVolume by default. As the result should be N, it implies (as stated by Bruno) that (by default) the unit of kn is N/m^3.
But using different Law2.volumePower, you can set different meaning of kn (N/m^2, N/m, etc.) and different behavior of the model.


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