/THERM_STRESS/MAT

Block Format Keyword

/THERM_STRESS/MAT - Thermal Material Expansion

Description

Used to add thermal expansion property for RADIOSS material (shell and solid).

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/THERM_STRESS/MAT/mat_ID
fct_IDT	Fscaley

Field	Contents	SI Unit Example
mat_ID	Material identifier (Integer, maximum 10 digits)
fct_IDT	Function identifier for defining thermal linear expansion coefficient as a function of temperature. (Integer)
Fscaley	Ordinate scale factor for thermal expansion coefficient function Default = 1.0 (Real)

2D Quad	8 node Brick	20 node Brick	4 node Tetra	10 node Tetra	8 node Thick Shell	16 node Thick Shell
√	√	√	√	√	√	√

= yes

blank = no

SHELL

TRUSS

BEAM

4-nodes shells: only for Belytshko-Tsai and QEPH elements

(Ishell =1, 2, 3, 4 and 24)
3-nodes shells: only for standard triangle
(Ish3n =1, 2)

= yes

blank = no

#RADIOSS STARTER

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#- 1. MATERIALS:

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/MAT/PLAS_JOHNS/1

Steel (unit: Mg_mm_s)

# RHO_I

7.8E-9

# E NU

210000 .3

# a b n EPS_p_max SIG_max0

270 450 .6 0 0

# c EPS_DOT_0 ICC Fsmooth F_cut Chard

0 0 0 0 0 0

# m T_melt rhoC_p T_r

0 0 0 0

/HEAT/MAT/1

# T0 RHO0_CP AS BS IFORM

273 3.588 1.9E-2 0 1

# Blank card

/THERM_STRESS/MAT/1

# fct_IDT Fscale_y

1003 0

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#- 2. FUNCTIONS:

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/FUNCT/1003

linear expansion coefficient function of temperature

# X Y

273 1.2E-5

800 1.2E-5

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#enddata

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

1.	The /THERM_STRESS/MAT option should be used with thermal material. /HEAT/MAT should be defined for thermal analysis and temperature change computation.

2.	For shells and solids, this option is available with all material laws.

3.	This option is not available for implicit analysis.

4.	The thermal expansion generates thermal strains which are defined as following:

is the isotropic thermal expansion coefficient

is the temperature gradient or temperature increment between current time and reference.

This change in temperature causes stress. The thermal stress is computed from Hook's law.

Where, H is the elasticity matrix.

To take thermal effect into account, this thermal stress is removed from total stress:

The total strain is considered as the sum of subsequently mechanical and thermal effect:

It is important to define boundary conditions with particular care for problems involving thermal loading to avoid over-constraining the thermal expansion. Constrained thermal expansion can cause significant stress, and it introduces strain energy that will result in an equivalent increase in the total energy of the model.