How can biological materials be analysed in OnScale?

As OnScale is a transient code, nonlinear analysis is quite straight-forward to perform. However the generation of nonlinear effects for wave-propagation is very much dependent on the material properties provided, in particular the 'B/A' value of the material.

OnScale supports this and has a material type called tisu for biological materials. When this material is used for the transmission media, nonlinear effects can be supported provided that pressure levels are high enough to initiate.

tisu materials require some extra inputs over conventional elas (linear elastic) materials:

  • B/A - 'b over a' (commonly known for biological materials)
  • Maximum pressure cut-off - pmax (negative number as compression is negative in OnScale)
  • Pressure cut-off - pcut (set to a large positive number for wave 'steepening')

For example:

c -------------------------------------------------------------------------
c fatnl : fat - nonlinear for type tisu
c pmax values used to prevent time step issues - set to appropriate value
c for individual application
c -------------------------------------------------------------------------
wvsp on
type tisu
symb pmax = 2.e6
symb pmaxn = -2.e6
symb ba = 10.0
prop fatnl 928. 1427. 0. 0.01 0.0 0.0
$ba $pmaxn $pmax
sdmp fatnl $freqdamp db 0.75 0. 1.e6 1.0 0.01