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7.7  FEM stack and case entries

Various information are stored in the model.Stack field. If you use a SDT handle refering to a feplot figure, modification of the model and case entries is often easier using cf.Stack calls (see feplot).

Currently supported entry types in the stack are


casedefines a case : boundary conditions, loading, ...
curvecurve to be used for simulations (see fe_curve).
infonon standard information used by solvers or meshing procedures (see below).
info,mapused to define a normal MAP, see feutil GetNormal for format
matdefines a material entry.
prodefines an element property entry.
SEdefines a superelement entry.
seldefines a element selection.
selndefines a node selection. Typically a structure with fields .ID giving the reference number and .data giving either node numbers or a node selection command.
setdefines a set that is a structure with fields .ID (a reference number of the set), .data (defines the data) and .type (nature of the set: NodeId, EltId, FaceId, EdgeId or DOF). .data contains NodeId for nodes, EltId for elements, two columns giving EltId and face/edge number (as detailed in integrules) for faces and edges, DOF values for DOF sets. Sets are often used to define loaded surfaces. The feutil AddSet commands let you define a set from a selection.
 For FaceId sets, a third column can be added to specify subgroups within the set and a .NodeCon sparse matrix can be used to specify nodes (rows) connected to each subgroup (column).

Currently reserved names for info entries are

DefaultZetavalue to be used as default modal damping ratio (viscous damping). The default loss factor if needed is taken to be twice that value.
EigOptgives real eigenvalue solver options (see fe_eig).
FluidEtaDefault loss factor for use in vibroacoustic fluid computations.
FreqFrequencies given as a structure with field .data with frequency values and .ID a integer identifier. A .unit field can specify rad/s,Hz,rev/mn,RPM. f=fe_def('DefFreq',model) is used to obtain the frequency vector in Hz.
NewNodeFrominteger giving the next NodeId to be used when adding nodes to the model (used by some commands of feutil).
Omegarotation vector used for rotating machinery computations (see fe_cyclic) can be specified as a structure for unit selection. For example r1=struct('data',250,'unit','RPM');f_hz=fe_def('deffreq',r1)
OrigNumberingoriginal node numbering (associated with feutil Renumber command). Two int32 columns giving original and new node numbers.
StressCritFcnstring to be evaluated for a specific stress criterion, see fe_stress.
Rayleighdefines a Rayleigh damping entry.
MifDesdefines the list of desired response output (see fe2xf).
NasJobOptstructure with options to be used for automated job runs by the NASTRAN job handler.
NastranJobEditcell array giving a list of job editing commands to be used through a naswrite EditBulk call.
TimeOptgives time solver options (see fe_time).

A case defines finite element boundary conditions, applied loads, physical parameters, ... The associated information is stored in a case data structure with fields


Case.Stacklist of boundary conditions, constraints, parametric design point, and loading cases that need to be considered. A table of accepted entries is given under fe_case. Each row gives {Type,Name,data}.
Case.T basis of subspace verifying fixed boundary conditions and constraints.
Case.DOF DOF definition vector describing the columns of T, the rows of T are described by the .DOF field of the model.

The various cases are then stored in the .Stack field of the model data structure (this is done by a call to fe_case). If you use a SDT handle refering to a feplot figure, modification of the case entries is often easier using cf.CStack calls (see feplot).


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