output dissipated energy and elastic energy

Submitted by June on Thu, 12/31/2020 - 10:20

Dear LIGGGHTS users,

I used the contact model hertz, and set computeDissipatedEnergy as well as computeElasticPotential on. The manual says this setting saves the dissipated energy and elastic potential for use in fix calculate/dissipated_energy and fix calculate/normal_elastic_energy.

But when I output the variable f_calculate/dissipated_energy, it reports ERROR: Invalid fix ID in variable formula.

Could you please tell me how to solve this problem?

Thank you in advance.

Best wishes,
June

Forums:

deepakpawar.2310 | Thu, 12/31/2020 - 11:21

Hello

I guess dissipation energy and elastic energy calculation is a premium feature of LIGGGGHTS and not available in the public version of LIGGGHTS.

Thanks

June | Thu, 01/07/2021 - 14:38

Thank you for your comments!
Is there a command to calculate dissipation energy and elastic energy directly in LIGGGHTS? Or could you please provide a method to calculate these two energies?

Best wishes,
June

deepakpawar.2310 | Tue, 01/12/2021 - 09:55

following patch code would be helpfull !!

fix GammaN all property/global gamman peratomtypepair 1 448428791.6
fix GammaT all property/global gammat peratomtypepair 1 448428791.6

compute cpg all pair/gran/local pos vel force force_normal force_tangential history contactArea delta

# conatact force
compute fxx all reduce sum c_cpg[10]
compute fyy all reduce sum c_cpg[11]
compute fzz all reduce sum c_cpg[12]

# velocity

compute vy all reduce sum c_cpg[7]
compute vy all reduce sum c_cpg[8]
compute vz all reduce sum c_cpg[9]

# maxioverlap

compute overlap all reduce sum c_cpg[15] >> normal overlap

variable strainenergy_N atom (1/2)*v_KN*(v_ovelap_normal)^2
variable strainenergy_T atom (1/2)*v_Kt*(v_ovelap_tangential)^2 >> Not sure about tangential overlap
>> KN and KT you can calcualate from expressions (link attched)

variable dissipationenergy_N atom (1/2)*v_GammaN*(v_VelocityNormal)^2
variable dissipationenergy_T atom (1/2)*v_GammaT*(v_relativeVelocityTangential)^2

see attched link
https://www.cfdem.com/media/DEM/docu/gran_model_hooke_stiffness.html