/INTER/TYPE5

Block Format Keyword

/INTER/TYPE5 - Interface Type 5

Description

This interface is used to simulate impacts between a master surface and a list of slave nodes. This interface is mainly used to:

•	simulate impact of beam truss spring nodes on a surface

•	simulate impact of a complex fine mesh on a simply convex surface

•	replace a rigid wall

See main limitations of this interface in Comment 1.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/INTER/TYPE5/inter_ID/unit_ID
inter_title
grnd_IDs	surf_IDm					Ibag	Idel
Stfac		Fric		Gap		Tstart		Tstop
IBC		IRM	Inacti
Ifric	Ifiltr	Xfreq			sens_ID

Read this input only if Ifric > 0

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
C1		C2		C3		C4		C5

Read this input only if Ifric > 1

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
C6

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 nodes group identifier (Integer)
surf_IDm	Master surface identifier (Integer)
Ibag	Airbag vent holes closure flag in case of contact Default = 0 (Integer) = 0: no closure = 1: closure
Idel	Node and segment deletion flag (Comment 4) Default = 0 (Integer) = 0: no deletion = 1: when all the elements (4-node shells, 3-node shells, solids) associated to one segment are deleted, the segment is removed from the master side of the interface. It is also removed in case of explicit deletion using RADIOSS Engine keyword /DEL in the Engine file. Additionally, non-connected nodes are removed from the slave side of the interface. = 2: when a 4-node shell, a 3-node shell or a solid element is deleted, the corresponding segment is removed from the master side of the interface. It is also removed in case of explicit deletion using RADIOSS Engine keyword /DEL in the Engine file. Additionally, non-connected nodes are removed from the slave side of the interface. = -1: same as =1, except non-connected nodes are not removed from the slave side of the interface. = -2: same as =2, except non-connected nodes are not removed from the slave side of the interface.
Stfac	Interface stiffness scale factor Default = 0.2 (Real)
Fric	Coulomb friction (Real)
Gap	Gap for impact activation (Real)
Tstart	Start time for contact impact computation (Real)
Tstop	Time for temporary deactivation (Real)
IBC	Deactivation flag of boundary conditions at impact (Boolean)
IRM	Renumbering flag for segments of the master surface (Integer) = 0: if segment is connected to a solid element its normal is reversed if entering the solid element (the segment is renumbered) = 1: normal is always reversed (segment 1234 is read 2143) = 2: normal is never reversed (segments connected to a solid element are not renumbered
Inacti	Removing the initial penetrations flag (Comment 12) (Integer) = 0: no action = 3: change slave node coordinates to avoid initial penetration = 4: change master node coordinates to avoid initial penetration
Ifric	Friction formulation flag (Comment 9) Default = 0 (Integer) = 0: static Coulomb friction law = 1: generalized viscous friction law = 2: Darmstad friction law = 3: Renard friction law
Ifiltr	Friction filtering flag (Comment 10) (Integer) = 0: no filter is used (default) = 1: simple numerical filter = 2: standard -3dB filter with filtering period = 3: standard -3dB filter with cutting frequency
Xfreq	Filtering coefficient. Should have a value between 0 and 1. (Real)
sens_ID	Sensor identifier to Activate/Deactivate the interface (Integer) If an identifier sensor is defined, the activation/deactivation of interface is based on sensor and not on Tstart or Tstop.
C1	Friction law coefficient (Real)
C2	Friction law coefficient (Real)
C3	Friction law coefficient (Real)
C4	Friction law coefficient (Real)
C5	Friction law coefficient (Real)
C6	Friction law coefficient (Real)

(1)-1	(1)-2	(1)-3	(1)-4	(1)-5	(1)-6	(1)-7	(1)-8
					IBCX	IBCY	IBCZ

Field	Contents	SI Unit Example
IBCX	= 1: Deactivation flag of X boundary condition at impact (Boolean)
IBCY	= 1: Deactivation flag of Y boundary condition at impact (Boolean)
IBCZ	= 1: Deactivation flag of Z boundary condition at impact (Boolean)

1.	The main limitations for this interface are:

•	the master segment normals must be oriented from master surface to the slave nodes;

•	on the master side, the segments must be connected to solid or shell elements;

•	the same node may not be put in the two impact surfaces;

•	some search problems (see Some Common Problems in the RADIOSS Theory Manual).

2.	All the normals of the master surface segments must be oriented toward the slave surface. Otherwise, mixing the orientation of the normals can lead to initial penetrations.

3.	Slave and master surfaces should be topologically different: a node cannot be on the two surfaces at the same time.

4.	Flag Idel =1 has a CPU cost higher than Idel =2.

5.	If the stiffness on the master side is much less than the stiffness on the slave side, the stiffness factor Stfac can be increased to a value greater than 1; otherwise the stiffness factor should have a value between 0 and 1.

6.	For example, the interface stiffness balance is:

Where, Em is the master stiffness, em is the master thickness, Es is the slave stiffness, and es is the slave thickness.

7.	If IBCX = 1, the boundary condition in X direction is deactivated. IBCY and IBCZ behave the same way respectively in Y and Z direction.

8.	Boundary conditions are only deactivated on slave nodes.

9.	For friction formulation:

•	If the friction flag Ifric > 0 (default), the old static friction formulation is used:

with (Coulomb friction)

•	If the friction flag Ifric > 0, new friction models are introduced. In this case, the friction coefficient is set by a function

where p is the pressure of the normal force on the master segment and V is the tangential velocity of the slave node.

Currently, the following formulations are available:

•	Ifric = 1 (generalized viscous friction law):

•	Ifric = 2 (Darmstad law):

•	Ifric = 3 (Renard law):

where,

First critical velocity must be different to 0 ().

First critical velocity must be less than the second critical velocity .

The static friction coefficient C1 and the dynamic friction coefficient C2, must be less than the maximum friction C3 ( and ).

The minimum friction coefficient C4 must be less than the static friction coefficient C1 and the dynamic friction coefficient C2 ( and ).

10.	If Ifiltr flag is not zero, the tangential forces are smoothed using a filter:

where, coefficient is calculated from:

if Ifiltr =1 , simple numerical filter

if Ifiltr =2 , standard -3dB filter, with , and T = filtering period

if Ifiltr =3 standard -3dB filter, with Xfreq = cutting frequency

11.	The coefficients C1 through C6 are used to define a variable friction coefficient for new friction formulations.

12.	Since the coordinate change will be irreversible, this action needs be made with great precaution because it may:

•	create other initial penetrations, if several surface layers are defined in the interfaces

•	create initial energy if node belongs to spring element

Inacti = 3 or 4 is only recommended for small initial penetrations