This node specifies tissue-specific attributes.

Attribute Meaning
enable When disabled, removes this tissue and affiliated attachments from the solve.
material Specifies the material model being used by this specific tissue. The default material is “StVK”. Other choices are: “NeoHookean”, “Corotational” and “Anisotropic”. See the “Elastic materials” section for a description of the different materials.

This more accurately prevents per element compression than using “poissonsRatio” on the zMaterial node. If this value is set too high, instabilities can occur. The default value is safe, but can be increased depending on your situation to better maintain volume.

Also consider with zMaterial.volumeConservation, which prevents both compression and expansion and is more stable.

N.B. This attribute does not apply to the “Corotational” and “Anisotropic” material models.

transverseAnisotropy This parameter only applies to the “Anisotropic” material model. It controls how much weaker the material is in the transverse (i.e., perpendicular) direction to the muscle fibers. A value of 1.0 means that the material is equally strong in all directions (i.e., isotropic material). A value of 0.1 means that the material is 10x weaker in the direction perpendicular to the muscle fiber, whereas a value of, say, 100, will generate a material that is 100x stronger in the perpendicular direction. The muscle fiber is needed to establish a direction of anisotropy. The muscle fiber does not actually need to be activated. If it is not activated, one obtains a passive tissue that is anisotropic. If activated, one obtains an anisotropic active muscle.
iParentTissue When connected to another tissue, this tissue becomes a subtissue of that one.
oChildTissue When connected to another tissue, that tissue becomes a subtissue of this one.
inertialDamping Inertial damping is a non-physical effect useful to enhance stability or handle non-physical inputs. Inertial damping prevents tissues from ‘feeling’ inertia due to large-scale motions. Small-scale deformations still have all of their inertia, so elastic waves travel through objects normally. Using this, tissues can be subjected to extreme acceleration without tearing themselves apart. This is very different from the mass and stiffness damping available on the zSolver node.
collisions Enables collision detection and response with this tissue.
collisionVolume Vertices from bodies that intersect this tissue (provided this tissue is a closed volume and not self intersecting) will be pushed out.
selfCollisions Enables self-collision detection and response.
hardContact When enabled, uses implicit hard contact forces - this is more numerically stable but comes at the cost of generating a larger system matrix to solve.
contactStiffness The stiffness of “softContact” springs. It controls the “hardness” of the contact between the two objects. Lower values may cause intersections to occur during contact, but will be more stable. Higher values will cause little or no intersection, but may require “hardContact” to be enabled and/or more solver substeps to be stable.
contactStiffnessExp The power to which the value of the “contactStiffness” is raised.
contactSliding When enabled, contacts are resolved with the freedom to slide tangentially