/INTER/TYPE2

Block Format Keyword Defines a TYPE2 tied interface that connects a set of secondary nodes to a main surface. It can be used to connect coarse and fine meshes, model spotwelds, rivets, and so on.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/INTER/TYPE2/inter_ID/unit_ID
inter_title
grnd_IDs surf_IDm Ignore Spotflag Level Isearch Idel2   dsearch

Read this input, if Spotflag = 20, 21, or 22:

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Rupt Ifiltr fct_IDsr fct_IDsn fct_IDst Isym Max_N_Dist Max_T_Dist
Fscalestress Fscalestr_rate Fscaledist Alpha Area

Read this input, if Spotflag = 25, 27 or 28:

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Stfac Visc     Istf      
Optional
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Ithe Kthe             Iproj

Definitions

Field Contents SI Unit Example
inter_ID Interface identifier

(Integer, maximum 10 digits)

 
unit_ID Unit Identifier

(Integer, maximum 10 digits)

 
inter_title Interface title

(Character, maximum 100 characters)

 
grnd_IDs Secondary node group identifier.

(Integer)

 
surf_IDm Main surface identifier.

(Integer)

 
Ignore Flag to ignore secondary nodes if no main segment found.
= 0
Set to the value defined in /DEFAULT/INTER/TYPE2.
= 1
Secondary nodes with no main segment found during the Starter are deleted from the interface.
= 2
Secondary nodes with no main segment found during the Starter are deleted from the interface, new calculation for dsearch, if dsearch = 0. 14
= 3
Secondary nodes with no main segment found during the Starter are deleted from the interface, new calculation for dsearch, if dsearch = 0. 14
= 1000 Default, if /DEFAULT/INTER/TYPE2 is not defined
No deletion of secondary nodes

(Integer) 12 13

 
Spotflag Spotweld formulation flag. 3 4 5 6 7 11
= 0
Set to the value defined in /DEFAULT/INTER/TYPE2.
= 1
Formulation is optimized for spot welds or rivets.
= 2
Same formulation as standard formulation. Required when using hierarchy levels. Not compatible with nodal time step /DT/NODA/CST.
= 4 Default if /CAA is used
Rotational DOF are not transmitted, if shells are used.
Not compatible with nodal time step /DT/NODA/CTS.
= 5 Default if /CAA is not used
Standard formulation.
= 20
Spotweld with failure where the stress is calculated using the shell and brick faces attached to the node.
= 21
Spotweld with failure where the stress is calculated using the shell elements attached to the node.
= 22
Spotweld with failure where the stress is calculated using the brick faces attached to the node.
= 25
Penalty formulation (not recommended). 19
= 27
Kinematic formulation similar to the Spotflag =5 with an automatic switch to penalty formulation when incompatible kinematic conditions occur. 20
= 28
Kinematic formulation similar to Spotflag =1 with an automatic switch to penalty formulation when incompatible kinematic conditions occur. 20
= 30
Formulation with cubic curvature of main segment. Not compatible with nodal time step /DT/NODA/CST.

(Integer)

 
Level Hierarchy level of the interface.

(Integer)

 
Isearch Search formulation flag for the closest main segment.
= 0
Set to the value defined in /DEFAULT/INTER/TYPE2.
= 1
Old formulation (only used for previous version).
= 2 Default, if /DEFAULT/INTER/TYPE2 is not defined
New improved formulation.

(Integer)

 
Idel2 Node deletion flag. 9 10 16
= 0
Set to the value defined in /DEFAULT/INTER/TYPE2.
= 1
The kinematic condition is suppressed on the secondary node, when all elements linked to the main segment are deleted. (The secondary node is removed from the interface).
= 2
The kinematic condition is suppressed on the secondary node, if the main element is deleted. (The secondary node is removed from the interface).
= 1000 Default, if /DEFAULT/INTER/TYPE2 is not defined
No deletion.

(Integer)

 
dsearch Distance for searching closest main segment.

Default value is the average size of the main segments. 13

(Real)

[ m ]
Rupt Failure model (only available with Spotflag 20, 21 or 22).
= 0
Set to 2.
= 1
Failure when ( N _ D i s t M a x _ N _ D i s t ) 2 + ( T _ D i s t M a x _ T _ D i s t ) 2 > 1
= 2 (Default)
Failure when Max_N_Dist or Max_T_Dist are reached.

(Integer)

 
Ifiltr Filter flag. 10
= 0 (Default)
No filtering.
= 1
Filtering (alpha filter).

(Integer)

 
fct_IDsr Stress factor vs stress rate function identifier. 6

(Integer)

 
fct_IDsn Max normal stress vs normal relative displacement function identifier (N_Dist).

This function must be defined. 6

(Integer)

 
fct_IDst Max tangential stress vs tangential relative displacement function identifier (T_Dist). This function must be defined. 6

(Integer)

 
Isym Asymmetric rupture flag. 6
= 0 (Default)
Symmetric rupture (traction and compression).
= 1
Asymmetric rupture (traction only, not in compression).

(Integer)

 
Max_N_Dist Maximum normal relative displacement.

Default = 1e+20 (Real)

[ m ]
Max_T_Dist Maximum tangential relative displacement.

Default = 1e+20 (Real)

[ m ]
Fscalestress Stress scale factor. 6

Default = 1.00 (Real)

[ Pa ]
Fscalestr_rate Stress rate scale factor. 6

Default = 1.00 (Real)

[ Pa s ]
Fscaledist Distance scale factor. 6

Default = 1.00 (Real)

[ m ]
Alpha Stress filter alpha value.

Default = 1 (Real)

 
Area Area of surface which used when the area computed from secondary node side is null or when secondary node is connected only to 1D element.

Default = 0.0 (Real)

[ m 2 ]
Stfac Stiffness factor (used only with Spotflag 25, 27 or 28).

Default = 1.0 (Real)

 
Visc Critical damping coefficient on interface stiffness (used only with Spotflag =25, 27 or 28).

Default = 0.05 (Real)

 
Istf Interface stiffness definition flag. 16 Only used with penalty formulations (Spotflag=25, 27 or 28).
= 0
Set to value defined in /DEFAULT/INTER/TYPE2.
= 1
Penalty stiffness is the main stiffness.
= 2
Default, if /DEFAULT/INTER/TYPE2 is not defined.
= 3
Penalty stiffness is the maximum of the main and secondary stiffness.
= 4
Penalty stiffness is the minimum of the main and secondary stiffness.
= 5
Penalty stiffness is the main and secondary stiffness in series.

(Integer)

 
Ithe (Optional) Heat transfer flag.
= 0 (Default)
No heat transfer.
= 1
Heat transfer between pieces in contact is activated.

(Integer)

 
Kthe (Optional) Heat exchange coefficient.

Default = 0.0

[ W m 2 K ]
Iproj (Optional) Secondary node projection flag. 18 (not available for Spotflag = 1, 28 and 30).
= 0
Set to 1.
= 1 (Default)
Improved distribution of secondary mass and inertia on the main segment to avoid negative masses on main nodes.
= 2
The secondary mass/inertia is not changed.

(Integer)

 

Comments

  1. Interface TYPE2 is a kinematic condition; no other kinematic condition should be set on any node of the secondary surface, except when Spotflag =25, 27 or 28.
  2. The dsearch is computed as (see Tied Interface (TYPE2) in the Radioss Theory Manual):
    (1)
    d search = 1 n i = 1 n d i
    with,
    n
    Being the number of main segments
    d i
    Tthe total length of all the main side segments
  3. Main nodes of an interface TYPE2 may be secondary nodes of another interface TYPE2 only if the hierarchy level of the first interface is lower than the hierarchy level of the second interface. Hierarchy levels are only available with Spotflag =2. It does not work if Spotflag =0 or Spotflag =1.

    A possible workaround is using Spotflag=2, which corresponds to the default formulation (Spotflag=0); except that it is not compatible with /DT/NODA/CST.

  4. Spotflag =2 is equivalent to formulation 0; except that it is not compatible with nodal time step /DT/NODA/CST.
  5. Spotflag =4 is recommended to connect SPH particles to a surface (refer to Smooth Particle Hydrodynamics (SPH)).
  6. Spotflag = 20, 21 or 22 can include falure and be used to model a glue connection. It is not compatible with nodel time step /DT/NODA/CST. The stress is computed for each secondary node according to the "equivalent" surface around the node.
    In this case, the force in secondary node will be scaled by reduced force coefficient Fac_N (Fac_T), which is computed as:(2)
    Fac _ N = min { σ N _ max 2 max [ ( σ N ( t ) ) 2 ,     10 20 ] ,   1 }
    (3)
    Fac _ T = min { σ T _ max 2 max [ ( σ T ( t ) ) 2 ,     10 20 ] ,   1 }

    The reduced force is compared to the max value:

    if σ N < σ N _ max , then Fac_N =1, which means the force will not be reduced.

    if σ N > σ N _ max , then F a c _ N = σ N _ max 2 max [ ( σ N ( t ) ) 2 , 10 20 ] , which means the force will be reduced.

    Here the max value will be defined by the user with:(4)
    σ N max = Fscale ( σ ˙ ) f s n ( Δ X N F s c a l e d i s t )
    (5)
    σ T max = Fscale ( σ ˙ ) f s t ( Δ X T F s c a l e d i s t )
    (6)
    Fscale ( σ ˙ ) = F s c a l e s t r e s s f s r ( σ ˙ F s c a l e s t r _ r a t e )

    While, f s n , f s t and f s r are functions of fct_IDsn, fct_IDst and fct_IDsr.

    Once the rupture criterion (defined by Rupt) is reached, the contact will be deleted.

    Here:
    • σ N _ max is the maximum normal stress value defined by fct_IDsn
    • σ N ( t ) is the normal stress
    • σ T_max is the maximum tangential stress value defined by fct_IDst
    • σ T ( t ) is the tangential stress
    • Fscalestress is the input constant stress factor
    • fct_IDsr is the input variable coefficient
    • fct_IDsn and fct_IDs are the input stress-displacement functions
    • Isym permits to choose between symmetric or asymmetric rupture (traction/compression). The initial direction from main surface to the secondary node defines the positive side (traction). If the distance is zero (secondary node lies on the main surface), the rupture will be symmetric, even with Isym =1.

    This failure option (Spotflag = 20, 21 or 22) can not be used in implicit.

  7. Spotflag =30: Secondary mass/inertia/stiffness distribution to the main node is based on the Kirschoff model: bi-cubic form functions are used instead of linear (standard formulation). It allows a softer contact behavior since the element shape curvature is taken into account in the force/moment transmission.
    Warning: This formulation is not compatible with solid elements, as it requires rotational DOF.
  8. If flag Idel2 =2, then when a 4-node shell, a 3-node shell or a solid element is deleted, it is also removed from the main side of the interface (the kinematic condition is suppressed on relative secondary nodes).
  9. The options Idel2 =1 and Idel2 =2 act if the main element is deleted using explicit deletion in Radioss Engine (using the keyword /DEL in Radioss Engine Input (/DEL/SHELL, /DEL/BRICK, ...)).
  10. If Ifiltr is set to 1, the normal and tangential stresses are filtered with an alpha filter, as:
    (7)
    σ N ( t )=Alpha σ N ( t )+( 1Alpha ) σ N ( tdt ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdm3aaS baaSqaaiaad6eaaeqaaOWaaeWaaeaacaWG0baacaGLOaGaayzkaaGa eyypa0JaamyqaiaadYgacaWGWbGaamiAaiaadggacqGHflY1cqaHdp WCdaWgaaWcbaGaamOtaaqabaGcdaqadaqaaiaadshaaiaawIcacaGL PaaacqGHRaWkdaqadaqaaiaaigdacqGHsislcaWGbbGaamiBaiaadc hacaWGObGaamyyaaGaayjkaiaawMcaaiabeo8aZnaaBaaaleaacaWG obaabeaakmaabmaabaGaamiDaiabgkHiTiaadsgacaWG0baacaGLOa Gaayzkaaaaaa@5911@
    (8)
    σ T ( t )=Alpha σ T ( t )+( 1Alpha ) σ T ( tdt ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Wdm3aaS baaSqaaiaadsfaaeqaaOWaaeWaaeaacaWG0baacaGLOaGaayzkaaGa eyypa0JaamyqaiaadYgacaWGWbGaamiAaiaadggacqGHflY1cqaHdp WCdaWgaaWcbaGaamivaaqabaGcdaqadaqaaiaadshaaiaawIcacaGL PaaacqGHRaWkdaqadaqaaiaaigdacqGHsislcaWGbbGaamiBaiaadc hacaWGObGaamyyaaGaayjkaiaawMcaaiabgwSixlabeo8aZnaaBaaa leaacaWGubaabeaakmaabmaabaGaamiDaiabgkHiTiaadsgacaWG0b aacaGLOaGaayzkaaaaaa@5B6D@
  11. Spotflag =25 (penalty formulation) will keep the penalty formulation during the whole run. The secondary node (of this contact) could also be the secondary node of another kinematic option, like rigid body.

    The penalty stiffness is constant, calculated by default as the mean nodal stiffness of main and secondary side. The stiffness factor, Stfac, may be used to modify it, if needed. The penalty stiffness will be multiplied by Stfac.

    A critical viscous damping coefficient (Visc) allows damping to be applied to the interface stiffness.

  12. If Ignore = 1, 2, or 3, the secondary nodes without a main segment found during the Starter, are deleted from the interface.
  13. If Ignore1000, dsearch is used.
    If Ignore = 2 or 3 and dsearch = 0, dsearch is computed, for each secondary node as:(9)
    δ 1 = 0.6 ( t h i c k n e s s _ s e c o n d a r y _ n o d e + t h i c k n e s s _ m a i n _ s e g m e n t )
    (10)
    δ 2 = 0.05 ( m a i n _ s e g m e n t _ d i a g o n a l )

    d s e a r c h = max ( δ 1 , δ 2 )

    For shells:
    • thickness_secondary_node = shell thickness of secondary
    • thickness_main_segment = shell thickness of main
    For solids:
    • thickness_secondary_node = 0
    If Ignore = 2:
    • thickness_main_segment = E l e m e n t _ v o l u m e S e g m e n t _ a r e a
    If Ignore = 3:
    • thickness_main_segment = 0
    If Ignore = 2 or = 3:
    • Thickness is retained in the following order: first from /PART definition, from /SHELL or /SH3N definition, then from /PROP definition.
  14. The contact is compatible with 2D-plane and -axisymmetrical simulations only for Spotflag=0 and in case of connecting to solid elements with Spotflag=0, then moments are not transferred.
  15. If flag Idel2 =1, then when all 4-node shells, all 3-node shells and all solid elements belonging to a main segment are deleted, this segment is also removed from the main side of the interface (the kinematic condition is suppressed on relative secondary nodes).
  16. Spotflag = 25, 27 or 28: Interface penalty stiffness is computed from both main segment stiffness Km and secondary node stiffness Ks, depending on Istf flag:
    • Istf = 1: K n = S t f a c K m
    • Istf = 2 (default): K n = S t f a c K m + K s 2 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGlbWaaS baaSqaaiaad6gaaeqaaOGaeyypa0Jaam4uaiaadshacaWGMbGaamyy aiaadogacqGHflY1daWcaaqaaiaadUeadaWgaaWcbaGaamyBaaqaba GccqGHRaWkcaWGlbWaaSbaaSqaaiaadohaaeqaaaGcbaGaaGOmaaaa aaa@45D5@
    • Istf = 3: K n = S t f a c max ( K m , K s )
    • Istf = 4: K n = S t f a c min ( K m , K s )
    • Istf = 5: K n = S t f a c K m K s K m + K s MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGlbWaaS baaSqaaiaad6gaaeqaaOGaeyypa0Jaam4uaiaadshacaWGMbGaamyy aiaadogacqGHflY1daWcaaqaaiaadUeadaWgaaWcbaGaamyBaaqaba GccqGHflY1caGGlbWaaSbaaSqaaiaacohaaeqaaaGcbaGaam4samaa BaaaleaacaWGTbaabeaakiabgUcaRiaadUeadaWgaaWcbaGaam4Caa qabaaaaaaa@4B4D@
  17. If Ithe >1, the material of the secondary side and main need to be a thermal material, using finite element formulation for heat transfer (/HEAT/MAT).

    Thermal conduction is computed when the secondary node falls into contact.

    The heat exchange is computed from main to secondary and from secondary to main:(11)
    ϕ c o n d = K t h e ( T s T m ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqy1dy2aaS baaSqaaiaadogacaWGVbGaamOBaiaadsgaaeqaaOGaeyypa0Jaam4s amaaBaaaleaacaWG0bGaamiAaiaadwgaaeqaaOWaaeWaaeaacaWGub Waa0baaSqaaiaadohaaeaaaaGccqGHsislcaWGubWaa0baaSqaaiaa d2gaaeaaaaaakiaawIcacaGLPaaaaaa@4709@
  18. By default, Iproj =1 is used to avoid having the wrong mass distribution when the secondary node is projected outside of the main element. The mass and inertia are distributed on the closest edge based on the projection of the secondary node on this edge. Use Iproj =2, to obtain the same results as Radioss version 14.0 or older.

    inter_type2_Iproj
    Figure 1.
  19. When using the penalty formulation Spotflag=25, moments cannot be transmitted from the secondary nodes to a main segment. Therefore, it is not recommended to use it for any connection where the secondary nodes have rotational degrees of freedom. This would include: shell to shell, spring to shell, shell to solid where the shell is secondary and solid is main. Due to this limitation and the lower robustness compared to kinematic formulations, it is recommended to use the mixed kinematic and penalty formulation, Spotflag =27 and 28.
  20. Spotflag =27 and 28 are a mixed kinematic and penalty formulation tied contact. By default, the kinematic formulation is used. Any secondary nodes with incompatible kinematic conditions are automatically switched to the penalty formulation. Incompatible kinematic conditions with rigid bodies, imposed displacements, imposed velocities, imposed accelerations, other tied contact secondary nodes, or boundary conditions will cause the switch to penalty formulation. A WARNING message is printed in the Starter output file when secondary nodes are switched to penalty formulation.

    The penalty formulation stiffness is constant and calculated using Istf and Stfac. A critical viscous damping coefficient (Visc) allows damping to be applied to the interface stiffness. The penalty formulation can transfer moments from the secondary nodes to the main segment.

  21. Unlike Spotflag =1, Spotflag =28 does not add any mass at time=0 when the main surface of the tied contact is a shell element. If the main surface is a solid element there could be some mass added. No mass is added when Spotflag =27 is used.