/MAT/LAW106 (JCOOK_ALM)

Block Format Keyword This law represents an isotropic elasto-plastic material using the Johnson-Cook material model. This model expresses material stress as a function of strain and temperature.

This law is not compatible with an EOS. The dependence between pressure and volumetric strain is linear. A built-in failure criterion, based on the maximum plastic strain is available. This material law is compatible with solid elements only.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/MAT/LAW106/mat_ID/unit_ID or /MAT/JCOOK_ALM/mat_ID/unit_ID
mat_title
ρi ρ0            
E ν fct_ID1 fct_ID2 fct_ID3      
a b n εpmax σmax
Pmin   Nmax Tol    
        m Tmelt Tmax
ρ0Cp     Tr    

Definition

Field Contents SI Unit Example
mat_ID Material identifier.

(Integer, maximum 10 digits)

 
unit_ID Unit Identifier

(Integer, maximum 10 digits)

 
mat_title Material title.

(Character, maximum 100 characters)

 
ρi Initial density.

(Real)

[kgm3]
ρ0 Reference density used in EOS (equation of state).

Default = ρ0=ρi MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHbpGCdaWgaaWcbaGaaGimaaqabaGccqGH9aqpcqaHbpGCdaWgaaWcbaGaamyAaaqabaaaaa@3CEF@ (Real)

[kgm3]
E If fct_ID1 = 0: Young's modulus.

If fct_ID1 ≠ 0: Ordinate scale factor of fct_ID1 and fct_ID2.

(Real)

[Pa]
ν If fct_ID3 = 0: Poisson's ratio.

If fct_ID3 ≠ 0: Ordinate scale factor of fct_ID3.

(Real)

 
fct_ID1 Function identifier defining Young’s modulus versus temperature when heating.

(Integer)

 
fct_ID2 Function identifier defining Young’s modulus versus temperature when cooling.

(Integer)

 
fct_ID3 Function identifier defining Poisson’s ratio versus temperature.

(Integer)

 
a Yield stress.

(Real)

[Pa]
b Plastic hardening parameter.

(Real)

[Pa]
n Plastic hardening exponent.

Default = 1 (Real)

 
εpmax Failure plastic strain.

Default = 1030 (Real)

 
σmax Maximum stress.

Default = 1030 (Real)

[Pa]
Pmin Pressure cutoff (< 0).

Default = -1030 (Real)

[Pa]
Nmax Maximum number of iterations to compute plastic strains.

Default = 1 (Integer)

 
Tol Tolerance.

Default = 10-7 (Real)

 
m Temperature exponent.

Default = 1.0 (Real)

 
Tmelt Melting temperature.
= 0
No temperature effect.

Default = 1030 (Real)

[K]
Tmax For T > Tmax: m = 1 is used.

Default = 1030 (Real)

[K]
ρ0Cp Specific heat per unit volume.

(Real)

[Jm3K]
Tr Reference temperature.

Default = 300K (Real)

[K]

Example (Metal)

Comments

  1. In this model, the material behavior is elastic-plastic and the yield stress is calculated as:(1)
    σ=(a+bεpn)(1(T)m) MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHdpWCcqGH9aqpdaqadaqaaiaadggacqGHRaWkcaWGIbGaeqyTdu2aaSbaaSqaaiaadchaaeqaaOWaaWbaaSqabeaacaWGUbaaaaGccaGLOaGaayzkaaWaaeWaaeaacaaIXaGaeyOeI0IaaiikaiaadsfadaahaaWcbeqaaiabgEHiQaaakiaacMcadaahaaWcbeqaaiaad2gaaaaakiaawIcacaGLPaaaaaa@490D@
    Where,(2)
    T*=T-TrTmelt-Tr MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamivamaaCaaaleqabaGaamOkaaaakiaad2dadaWcaaqaaiaadsfacaWGTaGaamivamaaBaaaleaacaWGYbaabeaaaOqaaiaadsfadaWgaaWcbaGaamyBaiaadwgacaWGSbGaamiDaaqabaGccaWGTaGaamivamaaBaaaleaacaWGYbaabeaaaaaaaa@439B@
    Where,
    εp
    Equivalent plastic strain
    T MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamivaaaa@36CF@
    Temperature
    Tr MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamivamaaBaaaleaacaWGYbaabeaaaaa@37F2@
    Reference temperature
    Tmelt MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamivamaaBaaaleaacaWGTbGaamyzaiaadYgacaWG0baabeaaaaa@3AC1@
    Melting temperature

    The material behaves as a linear-elastic material when the equivalent stress is lower than the yield stress.

    When /HEAT/MAT (with Iform =1) references this material model, the values of Tr and Tmelt defined in this card will be overwritten by the corresponding T0 and Tmelt defined in /HEAT/MAT.

    When the temperature is not initialized using /HEAT/MAT or /INITEMP, the reference temperature (Tr) is also the initial temperature.

  2. The plastic yield stress should always be greater than zero. To model pure elastic behavior, the plastic yield stres,s a can be set to 1030.
  3. When εp reaches the value of εpmax (for tension, compression or shear), in one integration point, then the deviatoric stress of the corresponding integration point is permanently set to 0; however, the solid element is not deleted.
  4. The plastic hardening exponent must be n1 MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOBaiabgsMiJkaaigdaaaa@395A@ .
  5. The hydrostatic pressure is linearly proportional to volumetric strain:(3)
    P=Kμ MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGqbGaeyypa0Jaam4saiabeY7aTbaa@3ABF@
    Where,
    K=E3(12v) MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKfMBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhiov2DaebbnrfifHhDYfgasaacH8WjY=vipgYlh9vqqj=hEeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9q8qqaq=dir=f0=yqaiVgFr0xfr=xfr=xb9adbaGaaiGadiWaamaaceGaaqaacaqbaaGcbaGaam4saiabg2da9maalaaabaGaamyraaqaaiaaiodadaqadaqaaiaaigdacqGHsislcaaIYaGaamODaaGaayjkaiaawMcaaaaaaaa@4101@
    Bulk modulus
    μ=ρρ01 MathType@MTEF@5@5@+=feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKfMBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhiov2DaebbnrfifHhDYfgasaacH8akY=xipgYlh9vqqj=hEeei0xXdbba9frFf0=yqFf0dbba91qpepeI8k8fiI+fsY=rqaqpepae9pg0FirpepesP0xe9Fve9Fve9qapdbaGaaiGadiWaamaaceGaaqaacaqbaaGcbaGaeqiVd0Maeyypa0ZaaSaaaeaacqaHbpGCaeaacqaHbpGCdaWgaaWcbaGaaGimaaqabaaaaOGaeyOeI0IaaGymaaaa@42BA@
    Volumetric strain
  6. This material can be used with the material options /HEAT/MAT and /VISC.