# MAT2

Bulk Data Entry Defines the material properties for linear, temperature-independent, and anisotropic materials for two-dimensional elements.

Attention: Valid for Implicit and Explicit Analysis

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MAT2 MID G11 G12 G13 G22 G23 G33 RHO
A1 A2 A12 TREF GE ST SC SS
RAYL ALPHA BETA

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MAT2 13 6.2+3     6.2+3   5.1+3 0.056
6.5-6 6.5-6   -500.0

## Definitions

Field Contents SI Unit Example
MID Unique material identification.
Integer
Specifies an identification number for this material.
<String>
Specifies a user-defined string label for this material entry. 2

No default (Integer > 0 or <String>)

Gij Material property matrix.

No default (Real)

RHO Mass density. Used to automatically compute mass for all structural elements.

No default (Real)

Ai Thermal expansion coefficient vector.

No default (Real)

TREF Reference temperature for the calculation of thermal loads. Data from the MAT2 entry is used directly, without adjustment of equivalent E, G, or NU values.

Default = blank (Real or blank)

GE Structural element damping coefficient. 9 10

No default (Real)

ST, SC, SS Stress limits in tension, compression and shear. Used for composite ply failure calculations.

No default (Real)

RAYL Continuation line flag for material-dependent Rayleigh damping.
ALPHA Material-dependent Rayleigh Damping coefficient for the mass matrix.

Default = blank (Real ≥ 0.0)

BETA Material-dependent Rayleigh Damping coefficient for the stiffness matrix.

Default = blank (Real ≥ 0.0)

1. The material identification number/string must be unique for all MAT1, MAT2, MAT8 and MAT9 entries.
2. String based labels allow for easier visual identification of materials, including when being referenced by other cards. (example, the MID field of properties). For more details, refer to String Label Based Input File in the Bulk Data Input File.
3. The mass density, RHO, is used to automatically compute mass for all structural elements.
4. The convention for the Gij in fields 3 through 8 is represented by the matrix relationship:(1)
$\left\{\begin{array}{c}{\sigma }_{1}\\ {\sigma }_{2}\\ {\tau }_{12}\end{array}\right\}=\left[\begin{array}{ccc}{\text{G}}_{11}& {\text{G}}_{12}& {\text{G}}_{13}\\ {\text{G}}_{12}& {\text{G}}_{22}& {\text{G}}_{23}\\ {\text{G}}_{13}& {\text{G}}_{23}& {\text{G}}_{33}\end{array}\right] \left(\left\{\begin{array}{c}{\epsilon }_{1}\\ {\epsilon }_{2}\\ {\gamma }_{12}\end{array}\right\}-\left(\text{T}-\text{TO}\right)\left\{\begin{array}{c}\text{A}1\\ \text{A}2\\ \text{A}12\end{array}\right\}\right)$
5. If this entry is referenced by the MID3 field (transverse shear) on the PSHELL, G13, G23, and G33 must be blank.
6. Unlike the MAT1 Bulk Data Entry, data from a MAT2 Bulk Data Entry is used directly, without adjustment of equivalent E, G, or NU values.
7. TREF is used as the reference temperature for the calculation of thermal loads.
8. The long field format may be used.
9. To obtain the damping coefficient GE, multiply the critical damping ratio, $C/{C}_{0}$ by 2.0.
10. TREF and GE are ignored, if a MAT2 entry is referenced by a PCOMP entry.
11. If a MAT2 card is pointed to by a MID4 on PSHELL, and has a material ID greater than 400,000,000, then the thermal membrane-bending coefficients A1, A2, and A12 have a modified interpretation, and represent [G]*[alpha], rather than [alpha]. Here, [G] is a matrix composed of G11, G22, through, G33. This is to maintain consistency with respective terms generated internally by the PCOMP card.
12. For material-dependent Rayleigh damping, the equivalent viscous damping, $C$ , is defined as:(2)
$C=\text{ALPHA}*M+\text{BETA}*K$
Where,
ALPHA and BETA
Defined on the RAYL continuation line on the material entry
$M$
Mass matrix
$K$
Stiffness matrix
Supported solutions for material-dependent Rayleigh damping on MAT2:
• Direct Frequency Response
• Modal Frequency Response
• Direct Transient Response
• Modal Transient Response
• Nonlinear Transient Analysis
• Explicit Dynamic Analysis
13. This card is represented as a material in HyperMesh.