The different elastic material types provided by OptiStruct are: isotropic, orthotropic, and an-isotropic materials. The material property definition cards are used to define the properties for each of the materials used in a structural model.

The MAT1 bulk data entry is used to define the properties for isotropic elastic materials. It can be referenced by any of the structural elements, and can also be referenced by any property card.

The MAT2 entry is used to define the properties for an-isotropic materials. It applies only to triangular or quadrilateral membrane and bending elements, and can only be referenced by PSHELL, PCOMP, and PCOMPG property cards. This material type specifies the relationship between the in-plane stresses and strains. The angle between the material coordinate system and the element coordinate system is specified on the connection cards.

The MAT4 entry is used to define the properties for isotropic elastic materials. It can be referenced by any of the structural elements, and can also be referenced by any property card.

The MAT5 entry is used to define the properties for an-isotropic elastic materials. It can be referenced by any of the structural elements, and can also be referenced by any property card.

The MAT8 card is used to define the properties for planar orthotropic elastic materials in two dimensions. Individual plys of a layered composite lay-up typically possess such orthotropic properties. Since layered composite laminates are modeled using shell elements, MAT8 property data can only be referenced by PSHELL, PCOMP, and PCOMPG property cards.

The MAT9 bulk data entry can be used to define the properties for an-isotropic elastic materials for three dimensional solid elements. The general an-isotropic stress-strain relationship linking the six independent stress components of the stress tensor at a point and the six independent strain components of the tensor at the point contain 21 independent constants in the elasticity matrix. These values are supplied using the MAT9 bulk data card. The MAT9 bulk data card is used with the CHEXA, CPENTA, CPYRA, and CTETRA solid elements, and can only be referenced on the PSOLID property card. The optional coordinate system in which MAT9 data are specified is supplied via the PSOLID bulk data entry.

The MAT10 bulk data entry is used to define material properties for fluid elements in coupled fluid-structural (acoustic) analysis. It may only be referenced on PSOLID entries with FCTN=PFLUID.

Temperature dependent material properties are defined using MATT1, MATT2, MATT8, and MATT9. All four have the same characteristics as described above. The temperature dependency of each property is defined through TABLEM1, TABLEM2, TABLEM3, or TABLEM4 table entries.

Composite laminates are defined using the PCOMP and PCOMPG properties. They are not material types; each ply in the laminate lay-up can reference a different material.

Nonlinear material properties are defined using MATS1. The nonlinear material characteristics may need the table input TABLES1. MATS1 is defined as an extension to a MAT1 with the same MID. MATS1 is applicable to all nonlinear solutions.

For geometric nonlinear subcases, more nonlinear material laws are available. As a general rule, material definitions that are only applicable in geometric nonlinear analysis are defined on extensions to a MAT1 material that defines the basic elastic properties. The extensions are grouped with the base entry by sharing the same MID. The table below lists the MATXyz extensions available. If a law requires material curves, TABLES1 entries are used.

Example

 

MAT1, 102, 60.4, , 0.33, 2.70e-6

MATX02, 102, 0.09026, 0.22313, 0.3746, 100.0, 0.175