(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

/FAIL/LAD_DAMA/mat_ID/unit_ID

K1

K2

K3

Y0

Yc

k

a

Ifail_sh

Ifail_so

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

fail_ID

#RADIOSS STARTER

/UNIT/1

unit for mat and failure

#              MUNIT               LUNIT               TUNIT

                   g                  mm                  ms

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/MAT/COMPSH/1/1

composite example

#              RHO_I

             .001506

#                E11                 E22                NU12     Iform                           E33

              144000               10000                 .25         0                         20000

#                G12                 G23                 G31              EPS_f1              EPS_f2

                4200                4200                4200                   0                   0

#             EPS_t1              EPS_m1              EPS_t2              EPS_m2                dmax

                   0                   0                   0                   0                   0

#              Wpmax               Wpref      Ioff                         ratio

             1000000                   0         0                             0

#                  b                   n                fmax

                   0                   0             1000000

#            sig_1yt             sig_2yt             sig_1yc             sig_2yc               alpha

               10100               10100               10100               10100                   0

#           sig_12yc            sig_12yt                c_12          Eps_rate_0       ICC

               10068               10068                   0                   0         0

#          GAMMA_ini           GAMMA_max               d3max

                   0                   0                   0

#  Fsmooth                Fcut

         0                   0

/FAIL/LAD_DAMA/1/1

#                 K1                  K2                  K3              Gamma1              Gamma2

                2000                2000                2000               1E-20               1E-20

#                 Y0                  YC                   K                   A             Tau_max

                  40                 160              100000                   1                 .01

# Ifail_sh  Ifail_so

         1         3

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#enddata

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

[2]

For Quad 2D element, only Mode II and Mode III are available.

Where, di is the internal damage parameters associated with its fracture mode.

The damage evolution law is controlled by equivalent damage energy release rate.

The evolution of the damage parameters is strongly coupled with coupling factor and . These two material parameters come from delamination tests.

For the present failure model, consider that d1 = d2 = d3 = d, with:

Where, d = 1

is a measure of the failure ductility, the lower the value the more ductile the failure.

is the minimum failure duration, for example, the increase of failure energy between Y0 and Yc cannot last for less than this value.

The function w(Y) is computed as:

If the damage parameter "d " < 1.0, the stressesare decreased according to the following function:

A relaxation technique is used by gradually decreasing the stress:

With,

where,

t is the time

tr is the start time of relaxation when the damage criteria is reached

is the time of dynamic relaxation

is the stress components at the beginning of damage

3.

The value of determines a period of time after failure criterion is reached when the stress in failed element is gradually reduced to zero, then the element is deleted. This is necessary to avoid instability coming from a sudden element deletion and failure "chain reaction" in the neighboring elements. With this value, elements will not be deleted, even if the failure criterion is reached. Normal value of is 10 times higher than the actual times step should be set in the card directly.

[1] O. Allix, P. Ladevèze, “Interlaminar interface modeling for the prediction of delamination”, Composite structure 22 (1992) 235-242.

[2] L. Gornet, “Finite Element Damage Prediction of Composite Structures”.