MATX70

Bulk Data Entry Defines additional material properties for tabulated visco-elastic foam material for explicit dynamic analysis.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MATX70 MID EMAX EPSMAX FSMOOTH F NLOAD NULOAD I  
               
If NLOAD ≥ 1, NLOAD times
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
  TIDL EPSRL FSCALL            
If NULOADNULOAD times
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
  TIDU EPSRU FSCALU            
               

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
MATX1 170 0.1   0.1 9.9E-07        
MAT70 170 1.0 0.8     1   4  
                   
  2                

Definitions

Field Contents SI Unit Example
MID Material ID of the associated MAT1. 1

No default (Integer > 0)

 
EMAX Maximum young modulus.

(Real > 0)

 
EPSMAX Maximum plastic (failure) strain.

(Real > 0)

 
FSMOOTH Strain rate smoothing flag.
OFF (Default)
ON
 
F Cutoff frequency for strain rate filtering.

Default = 1.E30 (Real ≥ 0)

 
NLOAD Number of loading stress-strain function.

Default = 1 (Integer ≥ 1)

 
NULOAD Number of unloading stress-strain function. If IFLAG in this card is 1, 2, 3, or 4, NULOAD must be 0.

Default = 1, if IFLAG = 0

Default = 0, if IFLAG = 1, 2, 3, 4

(Integer > 0)

 
I Flag to control the loading/unloading behavior. 5
0 (Default)
Behavior follows the loading and unloading curves respectively.
1
Behavior follows the loading/unloading curves. For unloading, the deviatoric stress is modified.
2
Behavior follows the loading/unloading curves. For unloading, the stress tensor is modified.
3
The loading curve is used for both loading and unloading. For unloading, the deviatoric stress is modified. The unloading curves are ignored.
4
The loading curve is used for both loading and unloading. For unloading, the stress tensor is modified. The unloading curves are ignored.

(Integer)

 
Shape factor.

Default = 1.0 (Real)

 
Hysteresis unloading factor.

Default = 1.0 (Real)

 
TIDL Identification number of TABLES1 entry that defines the loading function.

(Integer > 0)

 
EPSRL Strain rate for loading function.

Default = 0.0 (Real)

 
FSCALL Scale factor for loading function.

Default = 1.0 (Real)

 
TIDU Identification number of TABLES1 entry that defines the unloading function.

No default (Integer > 0)

 
EPSRU Strain rate for unloading function.

Default = 0.0 (Real)

 
FSCALU Scale factor for unloading function.

Default = 1.0 (Real)

 

Comments

  1. The material identification number must be that of an existing MAT1 Bulk Data Entry. Only one MATXi material extension can be associated with a particular MAT1.
  2. MATX70 is only applied in explicit dynamic analysis subcases which are defined by ANALYSIS = EXPDYN. It is ignored for all other subcases.
  3. This material law can be used only with solid elements. The corresponding PSOLIDX property must define I = 1 (Belytschko element), I = 1 (small strain), and I = OFF (not co-rotational).
  4. The loading and unloading functions use engineering stress-strain curve.


    Figure 1. Loading and Unloading Stress-Strain Curves
  5. The loading and unloading behavior is determined by IFLAG.
    • IFLAG = 0 - The material behavior follows the defined curves for loading and unloading. NLOAD and NULOAD must be greater than 0.
    • I = 1 - Both loading curves are used respectively. For unloading, the deviatoric stress is modified by using the quasi-static unloading curve.(1)
      σ = ( 1 D ) ( σ + p l ) p l MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4WdmNaey ypa0ZaaeWaaeaacaaIXaGaeyOeI0IaamiraaGaayjkaiaawMcaamaa bmaabaGaeq4WdmNaey4kaSIaamiCaiabgwSixlaadYgaaiaawIcaca GLPaaacqGHsislcaWGWbGaeyyXICTaamiBaaaa@4A34@

      Where, D MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiraaaa@36BF@ is calculated from the quasi-static unloading curve.

      D = ( σ unloading σ quasi-static ) ,   σ unloading σ quasi-static are the current stresses computed respectively from the unloading and quasi-static curves.

      The pressure is: (2)
      p = ( σ x x + σ y y + σ z z ) / 3 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiCaiabg2 da9iabgkHiTmaabmaabaGaeq4Wdm3aaSbaaSqaaiaadIhacaWG4baa beaakiabgUcaRiabeo8aZnaaBaaaleaacaWG5bGaamyEaaqabaGccq GHRaWkcqaHdpWCdaWgaaWcbaGaamOEaiaadQhaaeqaaaGccaGLOaGa ayzkaaGaai4laiaaiodaaaa@497A@
    • I = 2 - Both loading and unloading curves are used respectively. For unloading, the stress tensor is modified using the quasi-static unloading curve σ = (1 - D) σ , where, D is calculated from the quasi-static unloading curve.

      D = ( σ unloading σ quasi-static ) ,   σ unloading σ quasi-static are the current stresses computed respectively from the unloading and quasi-static curves.

    • I = 3 - The loading curves are used for both loading and unloading behavior. The unloading curve is ignored. The deviatoric unloading stress is modified using:(3)
      σ = ( 1 D ) ( σ + p I ) p I MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4WdmNaey ypa0ZaaeWaaeaacaaIXaGaeyOeI0IaamiraaGaayjkaiaawMcaamaa bmaabaGaeq4WdmNaey4kaSIaamiCaiabgwSixlaadYgaaiaawIcaca GLPaaacqGHsislcaWGWbGaeyyXICTaamiBaaaa@4A34@
      (4)
      D = ( 1 H y s ) ( 1 ( W c u r W max ) S h a p e )

      Where, Wcur and Wmax are the current and maximum energy, respectively.

    • I = 4 - The loading curves are used for both loading and unloading behavior. The unloading curve is ignored. The unloading stress tensor is modified using σ = ( 1 D ) σ MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4WdmNaey ypa0ZaaeWaaeaacaaIXaGaeyOeI0IaamiraaGaayjkaiaawMcaaiab eo8aZbaa@3E7C@ (5)
      D = ( 1 H y s ) ( 1 ( W c u r W max ) S h a p e )

      Where, Wcur and Wmax are the current and maximum energy, respectively.

    • For I = 3, 4 the unloading curves are not used
  6. For stresses above the last load function, the behavior is extrapolated by using the two last load functions. In order to avoid huge stress values, it is recommended to repeat the last load function.
  7. When maximum plastic strain EPSMAX is reached, EMAX is used whatever the curve definition is.
  8. If EMAX is blank, EMAX is set and equal to Young modulus on MAT1 card.
  9. If EPSMAX is blank, it will be calculated automatically if EMAX is less than the maximum tangent according to the input stress-strain curves.
  10. Young's modulus E on MAT1 card would be modified automatically if it is less than the initial value according to the input stress-strain curves' tangents.
  11. This card is represented as a material in HyperMesh.