PolymerFEM - Constitutive Models FAQ

Here you can find answers to questions about how the board works. Use the links or search box below to find your way around.

Conversion Between Elastic Constants

The following table shows how to convert between elastic constants (Young's modulus, Poisson's ratio, Lame's constants) in different formats:

Running ANSYS from command line

I often run ANSYS from the command line. One way to do this is to use the command:

ansys140 -i simulation_file.dat -j res_file -o res_file.log -b -np 4

  • -i specifies the input file
  • -j specifies the base name of the job files
  • -o specifies the name of the log file
  • -b specifies that the simulation should run in batch mode
  • -np specifies the number of CPUs to use for the calculation

Filler particle concentration - definitions

  • mf = mass of filler particles
  • mr = mass of rubber (resin)

PHR = parts per hundred of filler particles by mass

That is, if PHR=10, then 10 kg of filler particles is added to 100 kg of raw rubber resin.

PHR = 100 * mf / mr

MASS FRACTION OF FILLERS = mf / (mf + mr) = PHR / (100 + PHR)

To get the volume fraction of fillers it is necessary to know the ratio of the density of the fillers to the density of the rubber resin:

VOL. FRAC. FILLERS = rhof/rhor * PHR / (100 + rhof/rhor * PHR)

Often, rho_fillers / rho_rubber = 0.5, giving
VOL. FRAC. FILLERS approx = 0.5 * PHR / (100 + 0.5 * PHR)

Neo-Hookean parameters in ABAQUS

ABAQUS requires that the neo-Hookean material parameters be expressed in terms of C10 and D1. These parameters can be obtained from the shear modulus (mu) and the bulk modulus (kappa) by the following expressions:

C10 = mu / 2

D1 = 2 / kappa

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