/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_fct   Fsmooth                Fcut
         1         1                   0
# YFun_IDN  YFun_IDT              SR_ref          Fscale_yld
         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:
   From relative displacement:

   • I_fail=0: Uni-directional formulation (uncoupled failure formulation)(1)
     $$Cs(t)=\max \left({\left|\frac{{\overline{u}}_N}{{\overline{u}}_{\max N}}\cdot {\alpha }_N\cdot {\mathrm{f}}_N\left({\dot{\overline{u}}}_N\right)\right|}^{{\exp }_N},{\left|\frac{{\overline{u}}_T}{{\overline{u}}_{\max T}}\cdot {\alpha }_T\cdot {\mathrm{f}}_T\left({\dot{\overline{u}}}_T\right)\right|}^{{\exp }_T}\right)>1$$
   • I_fail=1: Multi-directional formulation (coupled failure formulation)(2)
     $$Cs(t)={\left|\frac{{\overline{u}}_N}{{\overline{u}}_{\max N}}\cdot {\alpha }_N\cdot {\mathrm{f}}_N\left({\dot{\overline{u}}}_N\right)\right|}^{{\exp }_N}+{\left|\frac{{\overline{u}}_T}{{\overline{u}}_{\max T}}\cdot {\alpha }_T\cdot {\mathrm{f}}_T\left({\dot{\overline{u}}}_T\right)\right|}^{{\exp }_T}>1$$
   From energy:(3)

   $$Ce(t)=\max \left[{\left(\frac{En}{E{N}_{\max }}\right)}^{N_n}+{\left(\frac{Et}{E{T}_{\max }}\right)}^{N_t},\frac{EI}{E{I}_{max}}\right]>1$$
   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.

3. A damage variable, $D$ is defined as maximum of the cumulative damage generated by relative displacement or energy:(4)
   $$D_{\max }=\max \left[{\displaystyle {\int }_0^t\left({\mathrm{C}s(t)|}_{\mathrm{C}s(t)>1}\right)dt},{\displaystyle {\int }_0^t\left({\mathrm{C}e(t)|}_{\mathrm{C}e(t)>1}\right)dt}\right]$$
   The element is deleted (or stress in local integration point is set to zero), if:(5)

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

   If $T_{\max }$ is equal to default value, failure is immediate.

   Otherwise, when $T_{\max }>D_{\max }>0$ , softening is applied (for all directions) as:(6)

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