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Block Format Keyword

/FAIL/CONNECT - Failure According (Normal and Tangential) Elongation Criteria and/or Energy Criteria

Description

Describes the failure model for CONNECTION material with elongation criteria and/or energy criteria.

Format

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/FAIL/CONNECT/mat_ID/unit_ID

expN

R_fct_IDN

Ifail

Ifail_so

ISYM

expT

R_fct_IDT

 

 

 

EImax

ENmax

ETmax

Nn

Nt

Tmax

Nsoft

AREAscale

 

 

 

 

Optional line:

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(2)

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(4)

(5)

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(8)

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fail_ID

 

 

 

 

 
hmtoggle_plus1Flag Definition

Field

Contents

SI Unit Example

mat_ID

Material identifier

(Integer, maximum 10 digits)

 

unit_ID

Optional unit identifier

(Integer, maximum 10 digits)

 

Failure relative displacement (elongation) in normal direction

Default = 1030  (Real)

 

expN

Failure exponent parameter in normal direction

Default = 1.0  (Real)

 

Normal direction scale factor

Default = 1.0  (Real)

 

R_fct_IDN

Identifier for failure scale factor in normal direction vs elongation rate function

(Integer)

 

Ifail

Failure formulation flag

Default = 0  (Integer)

= 0: uni-directional failure

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

= 1: multi-directional failure

 

Ifail_so

Solid failure flag

Default = 1  (Integer)

= 1: the solid element is deleted, when one integration point reaches the failure criteria

= 2: the solid element is deleted, when all integration points reach the failure criteria

 

ISYM

Rupture deactivation flag for compression

Default = 0  (Integer)

= 0: Same behavior in tension and compression

= 1: Deactivation of failure in case of compression

 

Failure relative displacement (elongation) in tangential plane

Default = 1030  (Real)

 

expT

Failure exponent parameter in tangential plane

Default = 1.0  (Real)

 

Scale factor in tangential plane

Default = 1.0  (Real)

 

R_fct_IDT

Identifier for failure scale factor in tangential plane vs elongation rate function

(Integer)

 

EImax

Failure internal energy, per surface unit

Default = 1030  (Real)

symbol_kg_s2

ENmax

Normal failure internal energy, per surface unit

Default = 1030 (Real)

symbol_kg_s2

ETmax

Tangential failure internal energy, per surface unit

Default = 1030  (Real)

symbol_kg_s2

Nn

Exponent for normal energy failure criteria

Default = 1.0  (Real)

 

Nt

Exponent for tangential energy failure criteria

Default = 1.0  (Real)

 

Tmax

Duration parameter for energy failure criteria

(Real)

 

Nsoft

Softening exponent for failure

Default = 1.0  (Real)

 

AREAscale

Failure scale factor for area increase (Comment 6)

Default = 0.0  (Real)

 

fail_ID

(Optional) Failure criteria identifier (Comment 4)

(Integer, maximum 10 digits)

 
hmtoggle_plus1Example (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

# YFct_IDN  YFct_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

                   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----|
hmtoggle_plus1Comments
1.This failure model is compatible only with the connection material, /MAT/CONNECT.
2.Solid element failure will occur when elongation values reach the criteria, or when the internal energy reaches the failure internal energy value.

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

3.A combined energy failure criteria is defined as such:

En and Et being the energy in the normal and the tangential direction, respectively.

A damage variable is defined, as follows:

Dmax = max(D1,D2 )

The element is deleted (or stress in local integration point is set to zero), if:

Dmax >  Tmax

(if Tmax is equal to default value, failure is immediate).

Otherwise, when

Tmax > Dmax > 0, softening is applied as follows (for all directions):

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 outputs (average value over integration point) are available:

/ANIM/BRICK/USR1 - where, EI is the inter energy.

/ANIM/BRICK/USR2

/ANIM/BRICK/USR3

/ANIM/BRICK/USR4

/ANIM/BRICK/USR5

/ANIM/BRICK/USR6

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 AREAscale factor, the whole element will be deleted. The default value is set to zero. The default value is set to zero. This causes no deletion, due to area increase. The application is to prevent shooting nodes, if the cohesive element nodes will be released, when surrounding elements start to fail and erode.

See Also:

Example 48 - Solid Spotweld