# Material Property Checks for MAT1

In addition to the property requirements, there are usage and recalculation rules for MAT1 data.

## Usage Rules

Element Type E G n
ROD, BEAM, BAR Used for bending and tension. Used for torsion. Unused.
QUAD, TRIA Used in combination with n for bending and membrane. Used for transverse shear. Used in combination with E for bending and membrane.
SOLID Used in combination with n. Unused. Used in combination with n.

## Recalculation Rules

In cases when not all material parameters are given for MAT1, here are the recalculation rules for the remaining parameters.
Note: In cases of two requested parameters, this is obvious; while in cases of a single requested parameter, you are making an assumption as to which one is assumed to be zero.
Given Mean
E G n E G n
given   given as given G = E / 2(1 + n) as given
given given   as given as given n = E/2G - 1
given given E = 2G(1 + n) as given as given
given     as given 0.0 0.0
given   0.0 as given 0.0
given not allowed

## Material Requirements

The property requirements on MAT1 vary depending on whether it is used for 1D, 2D, or 3D elements. The details are provided in the table below.
Material Requirements MAT1 - 1D MAT1 - 2D MAT1 - 3D
Mathematical n = -1 results in error termination. n = -1 or n = 1 results in error termination. n = -1 or n = 0.5 results in error termination.
Semi-stability E ≤ 0 or G ≤ 0 results in error termination.

PARAM,CHECKMAT,NO will disable this error.

n ≤ -1 or n > 0.5 results in a warning (however, this is unused in 1D).

E ≤ 0, G ≤ 0, n ≤ -1 ≥ or -n > 0.5 results in error termination.

PARAM,CHECKMAT,NO will disable this error.

E ≤ 0, n ≤ -1, or n > 0.5 results in error termination.

PARAM,CHECKMAT,NO will disable this error.

Not all zeros If both E = 0 and G = 0, an error termination occurs.

If either E = 0 or G = 0, a warning is given.

If both E = 0 and G = 0, an error termination occurs.

If either E = 0 or G = 0, a warning is given.

E ≤ 0 results in error termination.
Consistency A warning is provided when G ≠ E / 2(1 + n). A warning is provided when G ≠ E / 2(1 + n). A warning is provided when G ≠ E / 2(1 + n).
Mathematical for composites   After homogenization, if either E = 0 or G = 0, an error termination occurs.