7.6 FEM model structure#
Finite element simulations are best handled using standard data structures supported by OpenFEM. The two main data structures are model which contains information needed to specify a FEM problem, and DEF which stores a solution.
Finite element models are described by their topology (nodes, elements and possibly coordinate systems), their properties (material and element). Computations performed with a model are further characterized by a case as illustrated in section 4.5.3 and detailed in section 7.7.
Data structures describing finite element models have the following standardized fields, where only nodes and elements are always needed.
| .bas | local coordinate system definitions. |
| .cta | sensor observation matrix.
Used by fe_sens. |
| .copt | solver options.
For use by upcom. This field is likely to disappear in favor of defaults in sdtdef. |
| .DOF | DOF definition vector for the matrices of the model. Boundary conditions can be imposed using cases. |
| .Elt | elements. This field is mandatory. |
| .wd | working directory |
| .file | Storage file name.
Used by upcom. |
| .il | element property description matrix. Can also be stored as 'pro' entries in the Stack. |
| .K{i} | cell array of constant matrices for description of model as a linear combination. Indices i match definitions in .Opt(2,:) and .Opt(3,:). Should be associated with a .Klab field giving a string definition of each matrix.
See details in the fe_super reference. |
| .mind | element matrix indices.
Used by upcom. |
| .Node | nodes. This field is mandatory. |
| .Opt | options characterizing models that are to be used as superelements. Second row gives MatType |
| .pl | material property description matrix. Can also be stored as 'mat' entries in the Stack. |
| .Patch | Patch face matrix.
See fe_super. |
| .Stack | A cell array containing optional properties further characterizing a finite element model. See stack_get for how to handle the stack and the next section for a list of standardized entries. |
| .TR | projection matrix.
See fe_super. |
| .unit | main model unit system (see fe_mat Convert for a list of supported unit systems and the associated two letter codes). Specifying this field let you perform conversion from materials defined in US system unit from the GUI. |
| .nmap | mapping between ids (NodeId, MatId, ProId, BasId, GID,...) and associated labels. This is managed by sdth urn.nmap |
Obsolete fields are .Ref Generic coordinate transformation specification, .tdof test DOF field (now in SensDof entries).