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TR.26.1 Define Material

This command may be used to specify the material properties by material name.  You will then assign the members and elements to this material name in the CONSTANTS command (See TR.26.2 Specifying Constants for Members and Elements for details and an example).
Note: ISOTROPIC materials can be assigned to all element types, 2DORTHOTROPIC materials should only be assigned to plate elements.

General Format

DEFINE MATERIAL

then

ISOTROPIC name
E f1
G f3
POISSON f6
DENSITY f7
ALPHA f8
DAMPING  f10
TYPE { STEEL | CONCRETE | ALUMINUM | TIMBER }

or

2DORTHOTROPIC name
E f1 (f2) 
G f3 (f4) (f5)
POISSON f6
DENSITY f7
ALPHA f8 (f9)
DAMPING  f10
TYPE { STEEL | CONCRETE | ALUMINUM | TIMBER }

Repeat ISOTROPIC or 2DORTHOTROPIC name and values for as many materials as desired then:

END MATERIAL (DEFINITION)

Where:

ParameterDescription
name material name (name of up to 36 characters)
f1, f2 specifies Young's Modulus (E). (f2 in local Y for 2DOthotropic materials). f1 defaults to 0.0, but a positive value must be entered or an error will ensue. f2 defaults to f1
f3, f4, f5 specifies Shear Modulus (G). For plates, the following are G values in local directions: f3 is the G for in-plane shear; f4 is the G for transverse shear in the local Y-Z direction; f5 is the G for transverse shear in the local Z-X direction. (Enter only for beams when the Poisson ratio is not in the range of 0.01 to 0.499.)

If f3 is not entered, then this value is calculated as G = 0.5×E/(1 + ν) (i.e., caluclated based on Young's modulus and Poisson's ratio). f4 defaults to f3 and f5 defaults to f4.

f6 specifies Poisson's Ratio (ν). This value must be in the range of 0.01 to 0.499. Poisson's ratio must be entered for orthotropic plates or when Poisson cannot be computed from G.
For Isotropic materials, this value defaults to a sliding scale value based on E:
  • 0.30 when E is near that of steel,
  • 0.33 when E is near that of aluminum,
  • 0.17 when E is near that of concrete
f7 specifies weight density (γ). Defaults to 0.0
f8, f9 Coefficient of thermal expansion. Defaults to 0.0. (f9 in local Y for 2DOthotropic materials, defaults to f8.)
f10 the damping ratio to be used in computing the modal damping by the composite damping method in a dynamic analysis when CDAMP has been specified. Damping must be in the range of 0.001 to 0.990. Defaults to 0.0

Note: Any material property which you do not explicitly specify is assumed to be the default value.

Tip: If one or more of the material properties is not explicitly specified, the results may be unpredictable or even incorrect with respect to the intended behavior. Therefore, it is best practice to always specify each material property for each defined material.

Example of an Isotropic Material

UNIT INCHES KIP
ISOTROPIC STEEL
E 29000
POISSON 0.3
DENSITY 0.000283
ALPHA 6e-06
DAMP 0.03
TYPE STEEL
STRENGTH FY 36 FU 58 RY 1.5 RT 1.2
END DEFINE MATERIAL

Example of a 2D Isotropic Material

UNIT MMS KN
DEFINE MATERIAL START
2DORTHOTROPIC GFRP
* Values in GPa
E 155 25
POISSON 0.33
DENSITY 1.96e-10
ALPHA 6e-06 10e-06
DAMPING 0.004
END DEFINE MATERIAL
Parent topic: TR.26 Specifying and Assigning Material Constants
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