MAT8

Bulk Data Entry

MAT8 – Material Property Definition, Form 8

Description

Defines the material properties for linear temperature-independent orthotropic material for two-dimensional elements.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
MAT8	MID	E1	E2	NU12	G12	G1,Z	G2,Z	RHO
	A1	A2	TREF	Xt	Xc	Yt	Yc	S
	GE	F12	STRN

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
MAT8	171	30.+6	1.+6	0.3	2.+6	3.+6	1.5+6	0.056
	28.-6	1.5-6	155.0

Field	Contents
MID	Unique material identification number. No default (Integer > 0)
E1	Modulus of elasticity in longitudinal direction (also defined as fibre direction or 1-direction) See comment 6. No default (Real ≠ 0.0)
E2	Modulus of elasticity in lateral direction (also defined as matrix direction or 2-direction) See comment 6. No default (Real ≠ 0.0)
NU12	Poisson’s ratio ( for uniaxial loading in 1-direction). Note that for uniaxial loading in 2-direction is related to by the relation . No default (Real)
G12	Inplane shear modulus. No default (Real > 0.0)
G1,Z	Transverse shear modulus for shear in 1-Z plane. Default = blank (Real > 0.0 or blank)
G2,Z	Transverse shear modulus for shear in 2-Z plane. Default = blank (Real > 0.0 or blank)
RHO	Mass density. No default (Real)
A1	Thermal expansion coefficient in 1-direction. No default (Real)
A2	Thermal expansion coefficient in 2-direction. No default (Real)
TREF	Reference temperature for the calculation of thermal loads. See comment 3. Default = blank (Real or blank)
Xt, Xc, Yt, Yc	Allowable stresses or strains in the longitudinal and lateral directions. Used for composite ply failure calculations. No default (Real > 0.0)
S	Allowable for in-plane shear stresses or strains for composite ply failure calculations. No default (Real > 0.0)
GE	Structural Element Damping Coefficient. TREF and GE are ignored, if a MAT8 entry is referenced by a PCOMP entry. No default (Real)
F12	Tsai-Wu interaction term for composite failure. No default (Real)
STRN	Indicates whether Xt, Xc, Yt, Yc, and S are stress or strain allowables. Default = blank (Real = 1.0 for strain allowables, blank for stress allowables)

Comments

1.	The material identification number must be unique for all MAT1, MAT2, MAT8 and MAT9 entries.

2.	If G1, Z and G2, Z values are specified as zero or are not supplied, a penalty term is used to enforce very high transverse shear stiffness.

3.	An approximate value for G1, Z and G2, Z is the inplane shear modulus G12. If test data is not available to accurately determine G1, Z and G2, Z for the material and transverse shear calculations, the value of G12 may be supplied for G1, Z and G2, Z.

4.	Long field format can be used.

The option of interpreting Xt, Xc, Yt, Yc, and S as strains is only available for composite definitions (PCOMP or PCOMPG) using the Maximum Strain (STRN) failure criterion. In this case, the STRN flag indicates whether Xt, Xc, Yt, Yc, and S are stress or strain allowables. For the STRN failure criterion, if the STRN field on MAT8 is set to “blank”, the strain allowables are calculated from the corresponding stress allowables.

For all other failure criteria Xt, Xc, Yt, Yc, and S are always interpreted as stresses, regardless of the value of the STRN flag.

6.	The value of E1 should be greater than that of E2 for the material to be stable. If E1 < E2, the material matrix becomes indefinite leading to an unstable material.

7.	This card is represented as a material in HyperMesh.