B.1 Standard Data Fields

FEBio Studio defines the following list of standard data fields that can be added to a post model.

Name	Description
Initial Position	The initial nodal position of the model
Aspect ratio	The element's aspect ratio
1-Princ curvature	The first principal curvature of the surface
2-Princ curvature	The second principal curvature of the surface
Gaussian curvature	The Gaussian curvature of the surface
Mean curvature	The mean curvature
RMS curvature	The Root-Mean-Square curvature
Princ Curvature difference	The difference of the principal curvatures
Congruency	The congruency
1-Princ curvature vector	The first principal curvature vector
2-Princ curvature vector	The second principal curvature vector

The following data fields require a “displacement” field.

Name	Description
Position	The current nodal position of the deformed model
Deformation gradient	The deformation gradient of the deformation map
Infinitesimal strain	The infinitesimal (engineering) strain tensor
Lagrange strain	The Green-Lagrange strain tensor
Right Cauchy-Green	The right Cauchy-Green deformation tensor
Right stretch	The right stretch tensor
Biot strain	The Biot strain tensor
Right Hencky	The Right Hencky tensor
Left Cauchy-Green	The left Cauchy-Green strain tensor
Left stretch	The left stretch tensor
Left Hencky	The left Hencky tensr
Almansi strain	The Almansi strain tensor
Volume	The element's (approximate) volume
Volume ratio	The ratio of current over initial element volume
Volume strain	The volumetric strain

The following data fields require a “stress” field.

Name	Description
pressure	Calculated from the “stress” field: \(p=-tr\boldsymbol{\sigma}\)