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

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. |