Material Property Checks for MAT1

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

Usage Rules for MAT1 Data

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 for MAT1

In cases when not all material parameters are given for MAT1, here are the recalculation rules for the remaining parameters. Note that 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 for MAT1

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.