7.3  Material property matrices and stack entries

This section describes the low level format for material properties.

The actual formats are described under m_ functions m_elastic, m_piezo, ...

For Graphical edition and standard scripts see section 4.5.1.

A material is normally defined as a row in the material property matrix pl.

Such rows give a declaration of the general form [MatId Type Prop] with

MatId	a positive integer identifying a particular material property.
Type	a positive real number built using calls of the form fe_mat('m_function',UnitCode,SubType), that encodes the material function used to interpret the material properties the material unit the material subtype See fe_mat Type for more details.
Prop	as many properties (real numbers) as needed (see fe_mat, m_elastic for details).

Additional information can be stored as an entry of type 'mat' in the model stack which has data stored in a structure with at least fields

.name	Description of material.
.pl	a single value giving the MatId of the corresponding row in the model.pl matrix or row of values.
	Resolution of the true .pl value is done by pl=fe_mat('getpl',model). The property value in .pl should be -1 for interpolation in GetPl, -2 for interpolation using the table at each integration point, -3 for direct use of a FieldAtNode value as constitutive value.
.unit	a two character string describing the unit system (see fe_mat Convert and Unit commands).
.type	the name of the material function handling this particular type of material (for example m_elastic).
.field	can be a structure allowing the interpolation of a value called field based on the given table. Thus mat.E=struct('X',[-10;20],'Xlab',{{'T'}},'Y',[10 20]*1e6) will interpolate value E based on field T. The positions of interpolated variables within the pl row are given by list=feval(mat.type, 'propertyunittype cell', subtype).