Cardiac mechanics benchmark case study- active contraction question

[kdwyer]

Hello,
In working through the cardiac mechanics benchmark case study I had a question I am hoping someone may be able to explain so I can better understand the material model part of it.
In the uncoupled prescribed uniaxial active contraction, is the active contraction along the prescribed fiber direction as defined by the (a) and (d) values under the mat_axis header from the C++ code. If so, what are the theta and phi variable representing?


Thanks so much for anyone's help,
Kiera

[ateshian]

Hi Kiera,

The <a> and <d> values define the local material axes (x-y-z coordinates) in each element. Then, the theta and phi variables represent the spherical angles for defining the direction of uniaxial contract relative to these local material axes. The special case theta=0, phi=90 means that the contraction is along the vector <a> (which is the x-component of the x-y-z local coordinate system in each element).

Best,

Gerard

[kdwyer]

Thanks so much for your reply that helped clarify a lot! Another question I am running into is for the material properties (such as E1, E2, E3 and G12, G31, G23), is there a default directionality assumed or is this based on the material axes too?

Thanks again!
Kiera