/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              

Definition

Field Contents SI Unit Example
mat_ID Material identifier.

(Integer, maximum 10 digits)

  
fct_IDT Function identifier for defining the instantaneous thermal linear expansion coefficient as a function of temperature.

(Integer)

  
Fscaley Ordinate scale factor for thermal expansion coefficient function.

Default = 1.0 (Real)

 [ 1 K ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeaaciGaaiaabeqaamaabaabaaGcbaWaamWaaeaada WcaaqaaiaaigdaaeaacaWGlbaaaaGaay5waiaaw2faaaaa@3981@

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----|
/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

  1. 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.
  2. For shells this option is available with all material laws.
  3. 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, 106.
  4. This option is not available for implicit analysis.
  5. The thermal expansion generates thermal strains which are defined as:(1)
    〈 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:(2)
    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.(3)
    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.