/THERM_STRESS/MAT
Block Format Keyword 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 |
Definitions
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) |
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 (Ishell =1, 2, 3, 4 and 24) 3-nodes shells: only for standard triangle (Ish3n =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----|
/MAT/PLAS_JOHNS/1
Steel (unit: Mg_mm_s)
# 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
# T0 RHO0_CP AS BS IFORM
273 3.588 19.0 0 1
# Blank card
/THERM_STRESS/MAT/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.
- For shells this option is available with all material laws.
- For solids this option is available only for material laws where the number goes from 1 to 28 and laws number 36, 42, 44, 45, 46, 47, 48, 49, 50, 56, 60, 62, 65, 66, 68, 69, 72, 74, 79, 81, 82, 88, 92, 103.
- This option is not available for implicit analysis.
- The thermal expansion
generates thermal strains which are defined as:
(1) Where, α is the isotropic thermal expansion coefficient.
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:(2) This change in temperature causes stress. The thermal stress can be calculated from Hook's law.(3) 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.