# MAT1

Bulk Data Entry Defines the material properties for linear, temperature-independent, and isotropic materials.

Attention: Valid for Implicit and Explicit Analysis

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MAT1 MID E G NU RHO A TREF GE
ST SC SS
MODULI MTIME
RAYL ALPHA BETA

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MAT1 17 3.+7   0.33 4.28

## 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>)

E Young's modulus.

Default = blank (Real or blank)

G Shear modulus.

Default = blank (Real or blank)

NU Poisson's ratio.

If < 0.0, a warning is issued.

Default = blank (-1.0 < Real < 0.5 or blank)

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

No default (Real)

A Thermal expansion coefficient.

No default (Real)

Default = 0.0 (Real)

GE Structural element damping coefficient. 10 11

No default (Real)

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

No default (Real)

MODULI Continuation line flag for moduli temporal property. 12
MTIME Material temporal property. This field controls the interpretation of the input material property for viscoelasticity.
INSTANT
This material property is considered as the Instantaneous material input for viscoelasticity on the MATVE entry.
LONG (Default)
This material property is considered as the Long-term relaxed material input for viscoelasticity on the MATVE entry.

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. Either E or G must be specified (that is, non-blank).
4. If any one of E, G, or NU is blank, it is computed to satisfy the identity,

E = 2(1+NU)G; otherwise, values supplied by you are used.

5. If E and NU are both blank, they are both given the value 0.0.
6. If G and NU are both blank, they are both given the value 0.0.
7. Unlikely data on one or more MAT1 entries result in a warning message. Unlikely data is defined as:
• E < 0.0 or
• G < 0.0 or
• NU > 0.5 or
• NU < -1.0 or
• $|1-\frac{\text{E}}{2\left(1+\text{NU}\right)\text{G}}|>0.01$
• except for cases covered by comments 5 and 6.
8. It is strongly recommended that only two of the three values E, G, and NU be input.
9. The large field format may also be used.
10. To obtain the damping coefficient GE, multiply the critical damping ratio, $C/{C}_{0}$ by 2.0.
11. TREF and GE are ignored, if a MAT1 entry is referenced by a PCOMP, PCOMPP, or PCOMPG Bulk Data Entries.
12. MODULI continuation line is only applicable when used together with the MATVE entry. Refer to MATVE which provides additional information on how this material input is interpreted.
13. For material-dependent Rayleigh damping, the equivalent viscous damping, $C$ , is defined as:(1)
$C=\text{ALPHA}*M+\text{BETA}*K$
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 MAT1:
• Direct Frequency Response
• Modal Frequency Response
• Direct Transient Response
• Modal Transient Response
• Nonlinear Transient Analysis
• Explicit Dynamic Analysis
Note: For cohesive elements that reference MAT1, material-based Rayleigh damping is only supported for Nonlinear Transient Analysis.
14. This card is represented as a material in HyperMesh.
Element Type E NU G
CROD, CBAR, CBEAM, and CWELD Axial and Bending N/A Transverse Shear and Torsion
CSHEAR N/A N/A Shear
CQUAD and CTRIA Membrane and Bending Membrane and Bending Transverse Shear
CHEX, CTETRA, CPENTA, CPRYRA and CSEAM Deformation N/A