/FAIL/CONNECT

Format

Definitions

Example (Spotweld)

#RADIOSS STARTER
/UNIT/1
unit for mat
                  Mg                  mm                   s
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  2. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/LAW59/1/1
spotweld
#              RHO_I
              7.9E-9
#                  E                   G     Imass
               21000               21000         0
# NB_funct   Fsmooth                Fcut
         1         1                   0
# YFun_IDN  YFun_IDT        SR_reference        Fscale_yield
         1         2                   0                   0
/FAIL/CONNECT/1
#          EPS_MAX_N               EXP_N             ALPHA_N R_fct_IDN     Ifail  Ifail_so      ISYM
                   1                   0                   0         0         0         1         0
#          EPS_MAX_T               EXP_T             ALPHA_T R_fct_IDT
                 1.8                   0                   0         0
#              EIMAX               ENMAX               ETMAX                  Nn                  Nt
                   0                   0                   0                   0                   0
#               Tmax               Nsoft           AREAscale
                   0                   0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  3. FUNCTIONS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1
New_function
#                  X                   Y
                   0                 250                                                            
                   1                 350                                                            
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/2
New_function
#                  X                   Y
                   0                 350                                                            
                   1                 350                                                            
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA
/END
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

1. This failure model is compatible only with the connection material, /MAT/LAW59 (CONNECT).
2. Failure criteria:

   Solid element failure will occur when displacement values reach the criteria, or when the internal energy reaches the failure internal energy value.

   I_fail control coupled or uncoupled failure formulation for are exclusive with each other. Displacement and energy criteria can be used simultaneously. Both energy criteria can be used simultaneously (based on EI_max and energy in both directions separately).

   • I_fail =0: Uni-directional formulation (uncoupled failure formulation)
     For displacement criteria:(1)

     $${\overline{u}}_i\cdot \mathrm{f}(\dot{\overline{u}})>{\overline{u}}_{maxi}$$

     with $i$ = 33 for normal direction and 13 or 23 for tangent directions.

     For energy criteria:(2)

     $$E_n>E{N}_{max}$$
     or, for each direction:(3)

     $$E_t>E{T}_{max}$$
     or, for total energy:(4)

     $$E\left(t\right)>E{I}_{max}$$
   • I_fail=1: Multi-directional formulation (coupled failure formulation)
     For displacement criteria:(5)

     $${\left|\frac{{\overline{u}}_N}{{\overline{u}}_{\max N}}\cdot {\alpha }_N\cdot {\mathrm{f}}_N\left({\dot{\overline{u}}}_N\right)\right|}^{{\exp }_N}\text{+}{\left|\frac{{\overline{u}}_T}{{\overline{u}}_{{\max }_T}}\cdot {\alpha }_T\cdot {\mathrm{f}}_T\left({\dot{\overline{u}}}_T\right)\right|}^{{\exp }_T}>1$$
     For energy criteria:(6)

     $${\left(\frac{En}{E{N}_{\max }}\right)}^{N_n}+{\left(\frac{Et}{E{T}_{\max }}\right)}^{N_t}>1$$

     With $EN$ and $ET$ being the energy in the normal and the tangential direction, respectively.

3. A damage variable is defined, as:(7)
   $$D_1={\displaystyle {\int }_0^t\langle {\frac{\mathrm{E}(t)}{E{I}_{\max }}|}_{E(t)\ge E{I}_{\max }}\rangle }dt$$
   (8)
   $$D_2={\displaystyle {\int }_0^t\langle {\mathrm{C}(t)|}_{\mathrm{C}(t)\ge 1}\rangle dt}$$
   (9)
   $$D_{\max }=max\left(D_1,D_2\right)$$
   The element is deleted (or stress in local integration point is set to zero), if:(10)

   $$D_{\max }\ge T_{\max }$$

   (if $T_{\max }$ is equal to default value, failure is immediate).

   Otherwise, when $T_{\max }>D_{\max }>0$ , softening is applied as follows (for all directions):(11)

   $$\sigma =\sigma {\left(1-\frac{D}{T_{\max }}\right)}^{N_{soft}}$$

   The energy failure parameter will be activated as of input version 120 in /BEGIN.

4. fail_ID is used with /STATE/BRICK/FAIL and /INIBRI/FAIL. There is no default value. If the line is blank, no value is output for the failure model variables in the /INIBRI/FAIL (written in .sta file with /STATE/BRICK/FAIL option).
5. The following animation (/ANIM/BRICK) and time history (/TH/BRICK) outputs are available using USR (maximum value over integration points):

   	EImax (only)	ENmax or ETmax (only)	EImax and (ENmax or ETmax)
   USR1	$\frac{EI}{E{I}_{\max }}$		$\max \left[{\left(\frac{En}{E{N}_{\max }}\right)}^{N_n}+{\left(\frac{Et}{E{T}_{\max }}\right)}^{N_t},\frac{EI}{E{I}_{\max }}\right]$
   USR2		${\left(\frac{En}{E{N}_{\max }}\right)}^{N_n}+{\left(\frac{Et}{E{T}_{\max }}\right)}^{N_t}$	${\left(\frac{En}{E{N}_{\max }}\right)}^{N_n}+{\left(\frac{Et}{E{T}_{\max }}\right)}^{N_t}$

   Where,

   EI

   Internal energy per connection element area

   En

   Internal energy in the normal direction per connection element area

   Et

   Internal energy in the shear direction per connection element area

   	Ifail=0	Ifail=1
   USR3	$\max \left[{\mathrm{f}}_N\left({\dot{\epsilon }}_N\right)\cdot \frac{{\epsilon }_N}{{\epsilon }_{\max N}},{\mathrm{f}}_T\left({\dot{\epsilon }}_T\right)\cdot \frac{{\epsilon }_T}{{\epsilon }_{\max T}}\right]$	${\mathrm{f}}_N\left({\dot{\epsilon }}_N\right)\cdot \frac{{\epsilon }_N}{{\epsilon }_{\max N}}$
   USR4	${\mathrm{f}}_T\left({\dot{\epsilon }}_T\right)\cdot \frac{{\epsilon }_T}{{\epsilon }_{\max T}}$	$c4={\mathrm{f}}_T\left({\dot{\epsilon }}_T\right)\cdot \frac{{\epsilon }_T}{{\epsilon }_{\max T}}$
   USR5		${\left|\frac{{\epsilon }_N}{{\epsilon }_{\max N}}\cdot {\alpha }_N\cdot {\mathrm{f}}_N\left({\dot{\epsilon }}_N\right)\right|}^{{\exp }_N}\text{+}{\left|\frac{{\epsilon }_T}{{\epsilon }_{{\max }_T}}\cdot {\alpha }_T\cdot {\mathrm{f}}_T\left({\dot{\epsilon }}_T\right)\right|}^{{\exp }_T}>1$
   USR6	$SOFT={\left(1-\frac{D}{T_{\max }}\right)}^{N_{soft}}$	$SOFT={\left(1-\frac{D}{T_{\max }}\right)}^{N_{soft}}$

6. The area is calculated as the mean value of the upper and lower surface of the solid element. If the actual area reaches the value of initial area multiplied by AREA_scale factor, the whole element will be deleted. If the elements attached to the connect elements fail, this option can be used to prevent shooting nodes due to large deformation of the connect elements.