Hey community,
i would like to insert 3 atom types:
1, material : cylinder surface of a rotating drum material steel
2. material : front and back covered with plexiglas / acrylic glass
3. material: particle zinc oxide
We have values for particle-steel and particle-plexiglas (Jenike Shear cell)
How do I have to set up these parameters, that I can handle these 3 different materials ? Which values are needed to be set up ?
fix id all property/global coefficientFriction peratomtypepair n_atomtypes value_11 value_12 .. value_21 value_22 .. .
(value_ij=value for the (static) coefficient of friction between atom type i and j; n_atomtypes is the number of atom types you want to use in your simulation)
Thank you very much for your help
I set up as the following :
--
group zincoxide type 1
group steel type 2
group plexiglas type 3
jsams | Fri, 05/04/2018 - 01:04
sample input
It depends on the contact model of your simulation, e.g. for a Hetz or Hooke model you need to define the following properties: Young's modulus, Poisson's ratio, coefficient of restitution, coefficient of (sliding) friction, probably a coefficient of rolling friction (in case you are using a rolling friction model, either cdt or espd2), and an additional damping coefficient (in case you are using the epsd or epsd3 rolling friction model).
The properties that Young's modulus and Poisson's ration need to be defined for each material (= 3 values each). The other parameters are defined for each atom pair type combination, resulting in a symmetric 3x3 matrix. In your case, it would look something like the following:
# YM= young's modulus, PR = poisson's ratio, CR = coeffcient of restitution, CF = coefficient of friction, CRF = coefficient of rolling friction, CRVD = coefficient of rolling viscous damping
# subsrcipts: z=zincoxide (type1), s=steel (type2), p=plexiglass (type3)):
fix m1 all property/global youngsModulus peratomtype YM_z YM_s YM_p
fix m2 all property/global poissonsRatio peratomtype PR_z PR_s PR_p
fix m3 all property/global coefficientRestitution peratomtypepair 3 CR_zz CR_zs CR_zp CR_sz CR_ss CR_sp CR_pz CR_ps CR_pp
fix m4 all property/global coefficientFriction peratomtypepair 3 CF_zz CF_zs CF_zp CF_sz CF_ss CF_sp CF_pz CF_ps CF_pp
fix m5 all property/global coefficientRollingFriction peratomtypepair 3 CRF_zz CRF_zs CRF_zp CRF_sz CRF_ss CRF_sp CRF_pz CRF_ps CRF_pp
fix m6 all property/global coefficientRollingViscousDamping 3 CRVD_zz CRVD_zs CRVD_zp CRVD_sz CRVD_ss CRVD_sp CRVD_pz CRVD_ps CR_pp
In case you use the hertz/stiffness or hooke/stiffness contact models, you would have to define constants related to the elastic spring and the viscoelastic damping constants k_n, k_t, gamma_n, and gamma_t. You can find more information in the documentation of the respective contact model.