Block Format Keyword This interface is used to simulate drawbeads. It is mainly used in the process industry to model metal forming.

Drawbeads are used to prevent the metal strip from sliding during the stamping process. Normals of the main segments must be oriented toward the secondary nodes (unsorted group).


(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
grnd_IDs surf_IDm   Iform            
Fn Ft DEPTH Tstart Tstop
Blank Format


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 unsorted node group identifier.


surf_IDm Main surface identifier.


Iform Friction penalty formulation type.
= 1
Viscous (total) formulation.
= 2 (Default)
Stiffness (incremental) formulation. Recommended when the loading speed is low.


Fn Drawbead normal force per unit length.


[ N m ]
Ft Drawbead restraining force per unit length.


[ N m ]
DEPTH The drawbead depth.


[ m ]
Tstart Start time for contact impact computation.


[ s ]
Tstop Temporary deactivation time.


[ s ]


  1. The node group for secondary surface must be an unsorted group (/GRNOD).
  2. Iform =1 is not available when using Idt =1 in option /ADMESH/GLOBAL.
  3. When Fn0, Normal force is computed. The normal force is due to the bending of the blank into the draw bead as the binder closes on the die. The total contact force is the sum of the restraining force and normal force.
  4. Fn represents a limiting value. The normal force begins to develop when the distance d between the blank and drawbead line is less than the drawbead depth (DEPTH). When the drawbead is close to blank (distance equal to depth), this normal force reaches a plateau Fn. The value of normal force depends on the penetration as described here:

    Figure 1.

    Where, δ = DEPTH d + Thickness Blank 2 .

  5. If DEPTH = 0 or F n DEPTH > Stiffness Blank stiffness, the slope of the linear part of the curve is reset to the stiffness of the blank so that the same time step than the one without normal force is used to guarantee the stability.