COMSOL Multiphysics™

elplastic
Purpose
elplastic
Define plastic strain variables.
Syntax
Description
el.elem = 'elplastic'
el.g{ig} = geomnum
el.vars{ivar} = varname
el.varsToCache = cachevarlist
el.varPairsToGpProcess{2*igpvar-1} = gpvarname
el.varPairsToGpProcess{2*igpvar} = gpvarexpr
el.geomdim{ig}{edim}.ind{eldomgrp} = domainlist
el.geomdim{ig}{edim}.Yield{eldomgrp} = yieldexpr
el.geomdim{ig}{edim}.EffStress{eldomgrp} = effstressexpr
el.geomdim{ig}{edim}.G{eldomgrp}{ivar} = gexpr
el.geomdim{ig}{edim}.gporder{eldomgrp} = iorder
The elplastic element defines the plastic strain variable names specified in the
vars field. For the syntax of the ind field, see elempty. The yield function is
effstressexpr-yieldexpr. For each strain variable in vars, the right-hand side of
the corresponding rate equation is gexpr times the plastic multiplier, lambda. See
“Continuum Application Modes”, section “Theory Background”, in the
Structural Mechanics Module User’s Guide. The gporder field specifies a
quadrature rule order, which should preferably be the same as the order used in the
assembly of the main equation.
The varsToCache field contains a list of variables that can be assumed not to
depend explicitly on the plastic strains. By specifying variable names representing
complicated material property expressions or interpolated data independent of the
plastic strains, it is possible to avoid repeated evaluation in the inner, plastic, loop.
In addition to the plastic strain variables, the varPairsToGpProcess field defines a
number of postprocessing variable-expression pairs, which, when evaluated, are
linearly extrapolated from the integration points. Use this feature, for example, to
avoid problems with non-convergent plastic strains at sharp geometry corners.
For each variable and integration point, the elplastic element declares an
additional degree of freedom, which appears in the solution vector. However,
consider these degrees of freedom to be internal data of the elplastic element.
They are updated only by a special procedure in the nonlinear solver.
Cautionary
Note that some of the field names are mixed case, and case matters. Also, the
domain-dependent fields do not accept empty entries for any domain group.
The elplastic element is available only if your license includes the Structural
Mechanics Module or the MEMS Module.
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