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220.127.116.11 Prescribed Uniaxial Active Contraction
The material type for prescribed active contraction along a single direction (or fiber) in a solid mixture of unconstrained materials is “prescribed uniaxial active contraction”. This material must be combined with a stable compressible material that acts as a passive matrix, using a “solid mixture” container as described in Section 18.104.22.168↑. The following material parameters need to be defined:
|<T0>||representing the prescribed stress||[P]|
In the reference configuration, the fiber is oriented along the unit vector , where are orthonormal basis vectors representing the local element coordinate system when specified (Section 4.1.1↑), or else the global Cartesian coordinate system. The active stress for this material is given by where is the stretched fiber orientation in the current (deformed) configuration.
Uniaxial contraction along , in a mixture containing a neo-Hookean solid.
<material id="1" type="solid mixture"> <mat_axis type="local">0,0,0</mat_axis> <solid type="neo-Hookean"> <E>1.0</E> <v>0.3</v> </solid> <solid type="prescribed uniaxial active contraction"> <T0 lc="2">1</T0> <mat_axis type="angles"> <theta>0</theta> <phi>90</phi> </mat_axis> </solid> </material>