/THERM_STRESS/MAT

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/THERM_STRESS/MAT/`mat_ID`
`fct_ID`_T	`Fscale`_y

Definition


Field	Contents	SI Unit Example
`mat_ID`	Material identifier. (Integer, maximum 10 digits)
`fct_ID`_T	Function identifier for defining the instantaneous thermal linear expansion coefficient as a function of temperature. (Integer)
`Fscale`_y	Ordinate scale factor for thermal expansion coefficient function. Default = 1.0 (Real)	$[\frac{1}{K}]$

Element Compatibility - Part 1


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

Element Compatibility - Part 2


SHELL	TRUSS	BEAM
4-nodes shells: only for Belytshko-Tsai and QEPH elements (`I`_shell =1, 2, 3, 4 and 24) 3-nodes shells: only for standard triangle (`I`_sh3n =1, 2)		✓

✓ = yes

blank = no

▸Example (Thermal)

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  1. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat
                  Mg                  mm                   s
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/PLAS_JOHNS/1/1
Steel 
#              RHO_I
              7.8E-9                   0
#                  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/1/1
#                 T0             RHO0_CP                  AS                  BS     
                 273               3.588                19.0                   0         
# Blank card

/THERM_STRESS/MAT/1/1
# func_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 funtion 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----|

Comments

The /THERM_STRESS/MAT option should be used with thermal material. This option is not compatible with ALE applications (/ALE, /EULER). There is no thermal coupling between an ALE thermal material and a Lagrangian thermal material. /HEAT/MAT should be defined for thermal analysis and temperature change computation.
This option is available for all material laws; except for the following:
LAW0, 5, 6, 11, 21, 26, 37, 41, 46, 51, 54, 97, 108, 113, 151, /MAT/B-K-EPS, /MAT/K-EPS, and /MAT/GAS
This option is compatible with equations of state, /EOS, only when used with the following materials: LAW3, 4, 12, and 49
This option is not available for implicit analysis.
The thermal expansion generates thermal strains which are defined as:
$〈 ε_{th} 〉 = 〈 α Δ T α Δ T α Δ T 0 0 0 〉$
Where, $α$ is the isotropic thermal expansion coefficient.
$Δ T = T - T_{r e f}$ is the temperature gradient or temperature increment between current time and reference.
The total strain is considered as the sum of subsequently mechanical and thermal effect:
$ε = ε_{t h} + ε_{m e c a}$
This change in temperature causes stress. The thermal stress can be calculated from Hook's law.
$σ_{th} = H ε_{t h}$
Where, $H$ is the elasticity matrix.
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.