CONTACT

Bulk Data Entry Defines a contact interface.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CONTACT CTID PID/

TYPE

/

MU1

 SSID MSID MORIENT SRCHDIS ADJUST CLEARANCE  
  DISCRET TRACK CORNER   ROT SORIENT      
The following continuation line is used to define surface smoothing for the contact interface. It can be repeated as required.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
+ SMOOTH SMSIDE SMREG            
The following continuation line is used to define surface properties which can be used to trigger edge to edge contact.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
+ PSURF PSID1 PSID2            
The following continuation line is used to define cohesive material property for cohesive zone contact.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
+ COHE MCOHEDID COHEGSET            

Example 1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CONTACT 5 SLIDE 7 8          
  N2S                

Example 2

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CONTACT 5 SLIDE 7 8          
  S2S                
  SMOOTH SLAVE 71            
  SMOOTH SLAVE 72            
  SMOOTH MASTER ALL            

Definitions

Field Contents SI Unit Example
CTID Contact interface identification number.

(Integer > 0)

  
PID Property identification number of a PCONT or PCONTX entry.

(Integer > 0)

  
TYPE Choose type of contact without pointing to contact property - respective default property settings will be used. Default settings can be changed using CONTPRM. 4
SLIDE (Default)
Sliding contact (applied to both open and closed contacts).
STICK
Contact with stick condition (applies to closed contacts only).
FREEZE
Enforced zero relative displacements on the contact interface (applies to both closed and open contacts).
  
MU1 Coefficient of static friction ( μ ). 5

(0.0 ≤ Real < 1.0)

  
SSID Slave entity identification number. 1 2

(Integer > 0)

  
MSID Master entity identification number. 1 3

(Integer > 0)

  
MORIENT Orientation of contact "pushout" force from master surface. Applies only to masters that consist of shell elements or patches of grids. Masters defined on solid elements always push outwards irrespective of this flag. 6 19
OPENGAP (Default)
The contact interface is assumed open.
OVERLAP
Slave and master bodies overlap.
NORM
Contact force is oriented along the vector normal to the master surface.
REVNORM
Contact force is oriented opposite to the default vector normal to the master surface.
  
SRCHDIS Search distance criterion for creating contact condition. When specified, only slave nodes that are within SRCHDIS distance from master surface will have contact condition checked. 6

Default = Twice the average edge length on the master surface. For FREEZE contact, half the average edge length. (Real > 0 or blank)

For Node-to-Node (N2N) discretization, the default is 0.0

  
ADJUST Adjustment of slave nodes onto the master surface at the start of a simulation. 6
NO (Default)
No adjustment.
AUTO
A real value equal to 5% of the average edge length on the master surface is internally assigned as the depth criterion.
Real ≥ 0.0
Value of the depth criterion which defines the zone in which a search is conducted for slave nodes (for which contact elements have been created). These slave nodes (with created contact elements) are then adjusted onto the master surface. The assigned depth criterion is used to define the searching zone in the pushout direction.
Integer > 0
Identification number of a SET entry with TYPE = GRID. Only the nodes on the slave entity which also belong to this SET will be selected for adjustment.

For Node-to-Node (N2N) discretization, the default is NO and Real value can be specified for the depth criterion, similar to other discretization types. AUTO and Integer do not apply for N2N discretization.

  
CLEARANCE Initial gap opening between master and slave, irrespective of the actual distance between the nodes. 6

Default = blank (Real or blank)

  
DISCRET Discretization approach type for the construction of contact elements. 1
N2S
Node-to-surface discretization.
S2S
Surface-to-surface discretization.
N2N
Node-to-node discretization. 3 15
blank (Default)
Surface-to-surface discretization if it is a FREEZE contact, the slave is not a set of grids and there is no heat transfer analysis; node-to-surface discretization, otherwise.
  
TRACK Activates Finite-Sliding contact. 10
SMALL (Default)
Small-Sliding contact is activated. This contact option applicable to contacts with small relative sliding between the master and slave.
FINITE
Finite-Sliding contact is activated. This contact option allows for the incorporation of finite (large) relative sliding between the master and slave.
CONSLI
Continuous-sliding contact is activated. This contact option allows for the incorporation of continuous (large) relative sliding between the master and slave. 11
  
CORNER Corner treatment for the slave surface of N2S and S2S contacts. 12
NO (Default)
No corner treatment.
AUTO
Corner treatment is turned on. 30 degree will be used as default break angle.
Real ≥ 0.0 and Real < 180.0
Degree value of break angle criterion which defines the break angle between the two surface elements that share an edge. The surface area around a slave node will be broken into surface patches at the edges that satisfy the break angle criterion.
  
ROT Constraining rotational DOFs for N2S freeze contact with large displacement.
YES (Default)
Rotational DOFs are constrained.
NO
Rotational DOFs are not constrained.
  
SORIENT Orientation of contact force applied on the slave surface (which should be in the same direction as the pushout force from the master surface). This field is only applicable to S2S contact with CONSLI. 19
REVNORM
Contact force is oriented along the vector normal to the slave surface.
NORM (Default)
Contact force is oriented opposite to the default vector normal to the slave surface.
  
SMOOTH Continuation lines for surface smoothing definition flag. 6  
SMSIDE Master and/or Slave side(s) of the contact interface to be smoothed. 6
MASTER
Master side of the contact interface.
SLAVE
Slave side of the contact interface.
BOTH
Both Master and Slave sides of the contact interface.

No default

 
SMREG Specifies the region at the Master/Slave surface to be smoothed. 6
ALL (Default)
The whole Master/Slave surface.
Integer > 0
Identification number of a SURF entry, which can be the same as or a portion of the Master/Slave surface. The error will happen if, SURF ID specified here is outside of the Master or Slave surface.
  
PSURF Continuation line for surface property assignment. Only supported for explicit analysis.  
PSID1 The PSURF entry ID which is used to define the slave surface property.

No default (Integer > 0)

  
PSID2 The PSURF entry ID which is used to define the master surface property.

No default (Integer > 0)

  
COHE Continuation line for cohesive material. 18  
MCOHEDID Identification number of MCOHED card that is referenced by the current contact.

No default (Integer > 0)

  
COHEGSET Cohered grid set. 14
CURRENT
Closed contact nodes are cohered, open contact nodes will be cohered after they closed during analysis.
ORIGIN
Only the initially closed contact nodes are cohered.
ALL (Default)
All slave nodes in the contact are cohered, initially open contact nodes are adjusted to master surface automatically.
Integer > 0
Refers to a grid set ID. Only the nodes included in the grid set are cohered. Initially open contact nodes are adjusted to master surface automatically.
  

Comments

  1. A general set of guidelines for slave/master selection are:
    • Select the surface with finer mesh as the slave and the other as the master.
    • Select the smaller surface as the slave and the other as the master.
    • Select the softer surface as the slave and the other as the master.

    For information regarding choosing between N2S and S2S contact, refer to Contact Discretization in the User Guide.

  2. The slave entity (SSID) always consists of grid nodes. It may be specified as:
    • A set of grid nodes defined using SET(GRID, ..) command
    • A surface defined using SURF command (the slave nodes are picked from the respective nodes of the SURF faces)
    • A set of elements (shells or solids) defined using SET(ELEM, ..) command. Slave nodes are picked from the respective nodes of the elements in the set. For 3D solids, only nodes on the surface of the solid body are selected; internal nodes are not considered.

    DISCRET=N2S is recommended if the slave entity is a set of grids (nodes) or a set of solid elements.

  3. The master entity (MSID) may be defined as:
    • A surface defined using SURF command.
    • A set of elements (shells or solids) defined using SET(ELEM, ..) command. For sets of 3D solids, element faces on the surface are automatically found and selected as master surface.
    • The MSID can be left blank or set the same as SSID to activate Self Contact condition. This is currently supported only for Node-to-Surface (N2S) and Surface-to-Surface (S2S) contact with Continuous Sliding (CONSLI). For further information, refer to Self-Contact in the User Guide.
    • For N2N discretization, MSID should refer to a GRID set defined by the SET entry.
  4. For information on the different contact interfaces (TYPE field options), refer to Contact Interface Types in the User Guide.
  5. MU1 directly on the CONTACT card allows for simplified specification of frictional contacts.
    Note: This implies MU2=MU1, unless MU2 is specified explicitly on the CONTPRM card. Also, the value of MU1 assigned on the CONTACT card must be less than 1.0 - to specify higher values of static coefficient of friction, the PCONT card must be used.

    If FRIC is not explicitly defined on the PCONTX/PCNTX# entries, the MU1 value on the CONTACT or PCONT entry is used for FRIC in the /INTER entries for Explicit Dynamic Analysis. Otherwise, FRIC on PCONTX/PCNTX# overwrites the MU1 value on CONTACT/PCONT. For further information regarding frictional contact, refer to Friction in the User Guide.

  6. For information regarding the different contact parameters (ADJUST, CLEARANCE, MORIENT, TRACK, SMOOTH, SRCHDIS, GPAD), refer to Contact Interface Parameters (Contact Control) in the User Guide.
  7. Contact stabilization for Surface-to-Surface Contact and Node-to-Surface contact can be activated using the CNTSTB Subcase Information and CNTSTB Bulk Data Entries. Additionally, PARAM, EXPERTNL,CNTSTB can be used to activate contact stabilization. The CNTSTB Bulk Data parameters override the parameter values for a particular subcase.
  8. Thermal-structural analysis problems involving contact are fully coupled since contact status changes thermal conductivity. For further information, refer to Contact-based Thermal Analysis in the User Guide.
  9. Applying rotational SPC on nodes which belong to a FREEZE contact should be avoided. Fixing the rotational degrees of freedom will prevent the rotation of these contact nodes even in the case of solid elements.
  10. Finite Sliding (TRACK=FINITE) option is currently supported only if TYPE=SLIDE or if friction (via MU1/CONTPRM/PCONT) is defined. For further information, refer to Finite Sliding (TRACK) in the User Guide.
  11. In continuous-sliding contact (TRACK=CONSLI), the contact search is conducted for every contact iteration. In the formulation of contact virtual work, every term is updated based on the status in current iteration. The contact tangent stiffness matrix is computed in a consistent way. Continuous-sliding contact is expected to produce more accurate results and in some cases, better convergence robustness, especially when very large sliding and/or distortion are present.
  12. Corner treatment is supported for N2S (only for TRACK=CONSLI) and S2S (for all TRACK options) contacts. When corner treatment is turned on (AUTO or Real value), the contact surface around a slave node may be divided into several continuous surface patches if break angle criteria are satisfied on one or more edges at the node. For each surface patch, a separate contact element will be created for the element stiffness matrix, element force vector and element history variables computation. Corner treatment may improve robustness and accuracy in some cases.
  13. The CONTACT entry is supported for:
    • Linear and Nonlinear Static Analysis
    • Linear and Nonlinear Transient Analysis
    • Linear Dynamic Analysis
    • Heat Transfer Analysis
    • Contact-based Thermal Analysis (HEAT)
    • Explicit Dynamic Analysis (EXPDYN)

    CONTACT entry is currently not supported in Flex Body Generation run.

  14. N2S option should be used to activate large shape change during shape optimization. Currently, large shape change is activated if the model has N2S contact or CGAP/CGAPG/CWELD/CFAST/CSEAM elements.
  15. N2N discretization is currently only supported for Small Displacement Nonlinear Analysis.
  16. The following comments apply to Edge-to-Edge contact via PSURF field.
    • PSURF field is only supported for explicit analysis.
    • The slave side must be surface-based (cannot be grid-based).
    • PSURF should be defined for both slave and master.
    • Shell boundary edges are not currently supported.
  17. Axisymmetric and plane-strain contacts are supported for axisymmetric elements (CQAXI, CTAXI, and CTRIAX6 elements) and plane-strain solid elements (CQPSTN and CTPSTN elements). The SURF entry can be used to define the Master and Slave surfaces.
    Axisymmetric and plane-strain contacts are currently supported for:
    • SMALL (small sliding) for both N2S and S2S discretization
    • CONSLI (continuous sliding) for N2S discretization
    Axisymmetric and plane-strain contacts are not supported for:
    • FINITE (finite sliding)
    • CONSLI (continuous sliding) for S2S discretization
    • Surface Smoothing
  18. Cohesive contact works only for small-sliding (TRACK=SMALL), frictionless (TYPE=SLIDE or MU1=0.0) N2S/S2S contact.
  19. In case of implicit analysis, the shell contact surface orientation must be user-defined.

    In case of explicit analysis, the shell contact surface orientation is automatically detected. Thus, the user does not need to define consistent orientations on the surface.

  20. This card is represented as a group in HyperMesh.