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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.

.baslocal coordinate system definitions.
.ctasensor observation matrix. Used by fe_sens.
.coptsolver options. For use by upcom. This field is likely to disappear in favor of defaults in sdtdef.
.DOFDOF definition vector for the matrices of the model. Boundary conditions can be imposed using cases.
.Eltelements. This field is mandatory.
.wdworking directory
.fileStorage file name. Used by upcom.
.ilelement 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.
.mindelement matrix indices. Used by upcom.
.Nodenodes. This field is mandatory.
.Optoptions characterizing models that are to be used as superelements.
.plmaterial property description matrix. Can also be stored as 'mat' entries in the Stack.
.PatchPatch face matrix. See fe_super.
.StackA 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.
.TRprojection matrix. See fe_super.
.unitmain 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.
.nmapmapping 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).

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