/FAIL/PUCK

Block Format Keyword Describes the Puck failure model.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/FAIL/PUCK/mat_ID/unit_ID
σ 1 t σ 2 t σ ¯ 12 σ 1 c σ 2 c
p 12 + p 12 p 22 τ max Ifail_sh Ifail_so
Optional Line
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
fail_ID                  

Definition

Field Contents SI Unit Example
mat_ID Material identifier

(Integer, maximum 10 digits)

 
unit_ID Unit Identifier

(Integer, maximum 10 digits)

 
σ 1 t Longitudinal tensile strength

Default = 1030 (Real)

[ Pa ]
σ 2 t Transverse tensile strength

Default = 1030 (Real)

[ Pa ]
σ ¯ 12 Shear strength

Default = 1030 (Real)

[ Pa ]
σ 1 c Longitudinal compressive strength

Default = 1030 (Real)

[ Pa ]
σ 2 c Transverse compressive strength

Default = 1030 (Real)

[ Pa ]
p 12 + Failure envelope factor 12 (+)

Default = 0 (Real)

 
p 12 Failure envelope factor 12 (-)

Default = 0 (Real)

 
p 22 Failure envelope factor 22 (-)

Default = 0 (Real)

 
τ max Dynamic time relaxation 5

Default = 1030 (Real)

[ s ]
Ifail_sh Shell failure model flag
= 1 (Default)
Shell is deleted, if damage is reached for one layer.
= 2
Shell is deleted, if damage is reached for all shell layers.

(Integer)

 
Ifail_so Solid failure model flag
= 1 (Default)
Solid is deleted, if damage is reached for one integration point of solid.

(Integer)

 
fail_ID Failure criteria identifier 4

(Integer, maximum 10 digits)

 

Example (Composite)

Strength ( σ 1 t , σ 2 t , σ 1 c , σ 2 c , σ ¯ 12 ) are taken from following tests. m1 is fiber direction.

fail_puck_example
#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat and failure
#              MUNIT               LUNIT               TUNIT
                   g                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  1. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/COMPSH/1/1
composite example
#              RHO_I
               .0015
#                E11                 E22                NU12     Iform                           E33
              114000                9650                .025         0                             0
#                G12                 G23                 G31              EPS_f1              EPS_f2
                6000                6000                6000                   0                   0
#             EPS_t1              EPS_m1              EPS_t2              EPS_m2                dmax
                   0                   0                   0                   0                   0
#              Wpmax               Wpref      Ioff                         ratio
                   0                   0         4                             0
#                  b                   n                fmax
                   0                   0                   0
#            sig_1yt             sig_2yt             sig_1yc             sig_2yc               alpha
                1E30                1E30                1E30                1E30                   0
#           sig_12yc            sig_12yt                c_12          Eps_rate_0       ICC
                1E30                1E30                   0                   0         0
#          GAMMA_ini           GAMMA_max               d3max
                   0                   0                   0
#  Fsmooth                Fcut
         0                   0
/FAIL/PUCK/1/1
#           Sigma1_T            Sigma2_T            Sigma_12            Sigma1_C            Sigma2_C
                1720                55.2                 103                 765                 503
#               P+12                P-12                P-22             Tau_max  Ifail_sh  Ifail_so
                   0                   0                   0                .005         1         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

  1. This failure model is available for Shell and Solid.
  2. The failure mode criteria is written as:
    • Fiber fraction failure:
      Tensile fiber failure mode: σ 11 > 0 (1)
      e f = σ 11 σ 1 t
      Compressive fiber failure mode: σ 11 < 0 (2)
      e f = | σ 11 | σ 1 c
    • Inter fiber failure:
      Mode A if σ 22 > 0 :

      fail_puck_modeA
      Figure 1.
      (3)
      e f = 1 σ ¯ 12 [ ( σ ¯ 12 σ 2 t p 12 + ) 2 σ 22 2 + σ 12 2 + p 12 + σ 22 ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8akY=xipgYlh9vqqj=hEeei0xXdbb a9frFf0=yqFf0dbba91qpepeI8k8fiI+fsY=rqaqpepae9pg0Firpe pesP0xe9Fve9Fve9qapdbaGaaiGadiWaamaaceGaaqaacaqbaaGcba GaamyzamaaBaaaleaacaWGMbaabeaakiabg2da9maalaaabaGaaGym aaqaaiqbeo8aZzaaraWaaSbaaSqaaiaaigdacaaIYaaabeaaaaGcda WadaqaamaakaaabaWaaeWaaeaadaWcaaqaaiqbeo8aZzaaraWaaSba aSqaaiaaigdacaaIYaaabeaaaOqaaiabeo8aZnaaDaaaleaacaaIYa aabaGaamiDaaaaaaGccqGHsislcaWGWbWaa0baaSqaaiaaigdacaaI YaaabaGaey4kaScaaaGccaGLOaGaayzkaaWaaWbaaSqabeaacaaIYa aaaOGaeq4Wdm3aaSbaaSqaaiaaikdacaaIYaaabeaakmaaCaaaleqa baGaaGOmaaaakiabgUcaRiabeo8aZnaaBaaaleaacaaIXaGaaGOmaa qabaGcdaahaaWcbeqaaiaaikdaaaaabeaakiabgUcaRiaadchadaqh aaWcbaGaaGymaiaaikdaaeaacqGHRaWkaaGccqaHdpWCdaWgaaWcba GaaGOmaiaaikdaaeqaaaGccaGLBbGaayzxaaaaaa@62F2@
      Mode C if σ 22 < 0 :

      fail_puck_modeC
      Figure 2.
      (4)
      e f = [ ( σ 12 2 ( 1 + p 22 ) σ ¯ 12 ) 2 + ( σ 22 σ 2 c ) 2 ] ( σ 2 c σ 22 )
      Mode B

      fail_puck_modeB
      Figure 3.

    e f = 1 σ ¯ 12 ( σ 12 2 + ( p 12 σ 22 ) 2 + p 12 σ 22 )

    If the damage parameter is e f 1.0 , the stresses are decreased by using an exponential function to avoid numerical instabilities. A relaxation technique is used by decreasing the stress gradually:(5)
    σ ( t ) = f ( t ) σ d ( t r )
    With,(6)
    f ( t ) = exp ( t t r τ max )

    and t t r

    Where,
    t
    Time
    t r
    Start time of relaxation when the damage criteria is assumed
    τ max
    Time of dynamic relaxation
    σ d ( t r )
    Stress at the beginning of damage
  3. The damage value, D is 0 D 1 . The status for fracture is:
    • Free, if 0 D < 1
    • Failure, if D = 1

    With D = Max ( e f ( tensile ) , e f ( compression ) , e f ( ModeA ) , e f ( ModeB ) , e f ( ModeC ) ) . This damage value shows with /ANIM/BRICK/DAMA or /ANIM/SHELL/DAMA.

  4. The fail_ID is used with /STATE/BRICK/FAIL and /INIBRI/FAIL. There is no default value. If the line is blank, no value will be output for failure model variables in the /INIBRI/FAIL (written in .sta file with /STATE/BRICK/FAIL option).
  5. After the failure criterion is reached, the τ max value determines a period of time when the stress in the failed element is gradually reduced to zero. When the stress reaches 1% of stress value at the start of failure, the element is deleted. This is necessary to avoid instabilities coming from a sudden element deletion and a failure “chain reaction” in the neighboring elements. Even if the failure criterion is reached, the default value of τ max = 1.0 E 30 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8akY=xipgYlh9vqqj=hEeei0xXdbb a9frFf0=yqFf0dbba91qpepeI8k8fiI+fsY=rqaqpepae9pg0Firpe pesP0xe9Fve9Fve9qapdbaGaaiGadiWaamaaceGaaqaacaqbaaGcba GaeqiXdq3aaSbaaSqaaiGac2gacaGGHbGaaiiEaaqabaGccqGH9aqp caaIXaGaaiOlaiaaicdacaWGfbGaaG4maiaaicdaaaa@4413@ results in no element deletion. Therefore, it is recommended to define τ max 10 times larger than the simulation time step.