/INTER/TYPE2

Block Format Keyword

/INTER/TYPE2 - Interface Type 2

Description

Defines a TYPE2 tied interface that kinematically connects a set of slave nodes to a master 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 or 26 (Optional):

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
Stfac		Visc				Istf

Read this input (Optional):

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
Ithe	Kthe								Iproj

Field	Contents	SI Unit Example
inter_ID	Interface identifier (Integer, maximum 10 digits)
unit_ID	Optional unit identifier (Integer, maximum 10 digits)
inter_title	Interface title (Character, maximum 100 characters)
grnd_IDs	Slave node group identifier (Integer)
surf_IDm	Master surface identifier (Integer)
Ignore	Flag to ignore slave nodes if no master segment found. (Integer) (Comments 12 and 13) = 0: default, set to the value defined in /DEFAULT/INTER/TYPE2. = 1: Slave nodes with no master segment found during the Starter are deleted from the interface = 2: Slave nodes with no master segment found during the Starter are deleted from the interface, new calculation for dsearch, if dsearch = 0 (Comment 14) = 3: Slave nodes with no master segment found during the Starter are deleted from the interface, new calculation for dsearch, if dsearch = 0 (Comment 14) = 1000: No deletion of slave nodes (default, if /DEFAULT/INTER/TYPE2 is not defined).
Spotflag	Spotweld formulation flag (Comments 3 through 7 and 11) (Integer) = 0: default, set to the value defined in /DEFAULT/INTER/TYPE2. = 1: formulation is optimized for spotwelds or rivets = 2: same formulation as standard formulation. Required when using hierarchy levels. Not compatible with nodal time step /DT/NODA/CST. = 4: rotational DOF are not transmitted (if shells are used) (default when /CAA is activated). = 5: standard formulation (default when /CAA is activated). = 20, 21, 22: formulation with failure. Not compatible with nodal time step /DT/NODA/CST. The stress is computed for each slave node according to the "equivalent" surface around the node. The equivalent surface is defined accordingly: = 20: surface computed using shell and brick faces attached to the node. = 21: surface computed using only the shell attached to the node. = 22: surface computed using only the brick faces attached to the node. = 25: penalty formulation = 26: penalty formulation with added transmission of rotational moments from slave to master. = 30: formulation with cubic curvature of master segment. Not compatible with nodal time step /DT/NODA/CST
Level	Hierarchy level of the interface (Integer)
Isearch	Search formulation flag for the closest master segment (Integer) = 0: default, set to the value defined in /DEFAULT/INTER/TYPE2. = 1: old formulation (only used for previous version) = 2: new improved formulation (default, if /DEFAULT/INTER/TYPE2 is not defined).
Idel2	Node deletion flag (Comments 9, 10 and 16) Default = 0 (Integer) = 0: default, set to the value defined in /DEFAULT/INTER/TYPE2. = 1: the kinematic condition is suppressed on the slave node, when all elements linked to the master segment are deleted. (The slave node is removed from the interface). = 2: the kinematic condition is suppressed on the slave node, if the master element is deleted. (The slave node is removed from the interface). = 1000: no deletion (default, if /DEFAULT/INTER/TYPE2 is not defined).
dsearch	Distance for searching closest master segment Default value is the average size of the master segments. (Comments 2 and 13) (Real)
Rupt	Failure model (only available with Spotflag 20, 21 or 22) (Integer) = 0: default, set to value defined in /DEFAULT/INTER/TYPE2. = 1: failure when = 2: failure when Max_N_Dist or Max_T_Dist are reached (default)
Ifiltr	Filter flag (Comment 10) (Integer) = 0: no filtering = 1: filtering (alpha filter)
fct_IDsr	Stress factor vs stress rate function identifier (Comment 6) (Integer)
fct_IDsn	Max normal stress vs normal relative displacement function identifier (N_Dist.) This function must be defined. (Comment 6) (Integer)
fct_IDst	Max tangential stress vs tangential relative displacement function identifier (T_Dist.) This function must be defined. (Comment 6) (Integer)
Isym	Asymmetric rupture flag (Comment 6) Default = 0 (Integer) = 0: symmetric rupture (traction and compression) = 1: asymmetric rupture (traction only, not in compression)
Max_N_Dist	Maximum normal relative displacement Default = 1e+20 (Real)
Max_T_Dist	Maximum tangential relative displacement Default = 1e+20 (Real)
Fscalestress	Stress scale factor (Comment 6) Default = 1.00 (Real)
Fscalestr_rate	Stress rate scale factor (Comment 6) Default = 1.00 (Real)
Fscaledist	Distance scale factor (Comment 6) Default = 1.00 (Real)
Alpha	Stress filter alpha value Default = 1 (Real)
Area	(Optional) Area of surface which used when the area computed from slave node side is null or when slave node is connected only to 1D element. Default = 0.0 (Real)
Stfac	(Optional) Stiffness factor (used only with Spotflag 25 or 26) Default = 1.0 (Real)
Visc	(Optional) Critical damping coefficient on interface stiffness (used only with Spotflag =25 or 26) Default = 0.05 (Real)
Istf	Interface stiffness definition flag (Comment 16). Only used with penalty formulations (Spotflag=25 or 26) (Integer) = 0: default, set to 2 = 1: Penalty stiffness is only based on master segment stiffness. = 2, 3, 4 and 5: penalty stiffness is computed from both master and slave characteristics.
Ithe	Heat transfer flag (Integer) = 0: no heat transfer = 1: heat transfer between pieces in contact is activated
Kthe	Heat exchange coefficient Default = 0.0
Iproj	Slave node projection flag (Comment 18) (not available for Spotflag = 1, 26 and 30). (Integer) = 0: default, set to 1 = 1: force slave projection position to master edge = 2: slave projection is not modified

1.	Interface type 2 is a kinematic condition; no other kinematic condition should be set on any node of the slave surface, except when Spotflag =25 or 26.

2.	The dsearch is computed as follows (see the RADIOSS Theory Manual):

with, n being the number of master segments, and di is the total length of all the master side segments.

3.	Master nodes of an interface type 2 may be slave nodes of another interface type 2 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 /SPH).

6.	For failure (Spotflag = 20, 21 or 22), it could model, for example, glue connection. In this case, the force in slave node will be scaled by reduced force coefficient Fac_N (Fac_T), which is computed as:

The reduced force is compared to the max value:

if , then Fac_N =1, which means the force will not be reduced.

if , then which means the force will then be reduced.

Here the max value will be defined by the user with:

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

Here:

•	is the maximum normal stress value defined by fct_IDsn

•	is the normal stress

•	is the maximum tangential stress value defined by fct_IDst

•	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 master surface to the slave node defines the positive side (traction). If the distance is zero (slave node lies on the master surface), the rupture will be symmetric, even with Isym =1.

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

Spotflag =30: Slave mass/inertia/stiffness distribution to the master 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, since 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 master side of the interface (the kinematic condition is suppressed on relative slave nodes).

9.	The options Idel2 =1 and Idel2 =2 act if the master 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 follows:

11.	Spotflag =25 (penalty formulation) will keep the penalty formulation during the whole run. The slave node (of this contact) could also be the slave node of another kinematic option, like rigid body.

The penalty stiffness is constant, calculated as the mean nodal stiffness of master and slave 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.

Spotflag =26 is similar to Spotflag =25, but with added transmission of rotational moments from slave to master.

12.	If Ignore = 1, 2, or 3, the slave nodes without a master segment found during the Starter, are deleted from the interface.

13.	If Ignore ≠ 1000, dsearch is used.

If Ignore = 2 or 3 and dsearch = 0, dsearch is computed, as follows for each slave node:

1 = 0.6 * (thickness_slave_node + thickness_master_segment)

2 = 0.5 * (master segment diagonal)

dsearch = max(1,2)

For shells:

•	thickness_slave_node = shell thickness of slave

•	thickness_master segment = shell thickness of master

For solids:

•	thickness_slave_node = 0

If Ignore = 2:

If Ignore = 3:

thickness_master 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 master segment are deleted, this segment is also removed from the master side of the interface (the kinematic condition is suppressed on relative slave nodes).

16.	Interface penalty stiffness is computed from both master segment stiffness Km and slave node stiffness Ks, depending on Istf flag:

Istf = 1: Kn = Stfac * Km

Istf = 2: (default)

Istf = 3: Kn = Stfac * max (Km,Ks)

Istf = 4: Kn = Stfac * min (Km,Ks)

Istf = 5:

17.	If Ithe >1, the material of the slave side and master need to be a thermal material, using finite element formulation for heat transfer (/HEAT/MAT).

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

The heat exchange is computed from master to slave and from slave to master:

18.

Iproj =1, if a slave node projection is outside of the master element, it is moved to the closest edge of the master element (in order to avoid using negative values for shape functions). This flag is activated by default. In order to ensure consistency with RADIOSS versions prior to V14.0 and avoid numerical differences, this option can be deactivated (Iproj =2).

inter_type2_Iproj

/INTER/TYPE2

/INTER/TYPE2

/INTER/TYPE2

See Also: