Applying tractions for cracks simulations

Dear lammps community,

I am quite a beginner both in molecular dynamics as well as in lammps. Therefore, I apologize for an eventually naive question.

The goal of my research is making some comparisons between continuum and atomistic crack growth. To this aim, the optimal choice for external loads would be surface tractions, applied to the layer of atoms surrounding the box. I wonder if this makes sense in an atomistic simulation, as I saw many examples where velocities were imposed instead.

I did try "bravely and naively", via the command fix setforce. The outcome was a displacement of the layer of atoms surrounding the box and no transmission of stresses throughout the system. Is it expected? If so, why? If not and of use, I am glad to add the set of commands of my input file.

Thanks in advance.
Best regards

Alberto Salvadori
Dipartimento di Ingegneria Civile, Architettura, Territorio e Ambiente (DICATA)
Facolta` di Ingegneria
Universita` di Brescia
via Branze 43
25123 Brescia
Italy
tel 030 3711239
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e-mail: [email protected]
web-page: http://dicata.ing.unibs.it/salvadori

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Your question is too vague. I would look
at the examples/crack/in.crack file and
see what it does for starters.

Steve