HOURGLS

Bulk Data Entry Defines hourglass control parameters to reduce spurious zero-energy modes in elements with reduced integration.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
HOURGLS HGID HGTYP HGFAC            

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
HOURGLS 2 2 .05            

Definitions

Field Contents SI Unit Example
HGID Hourglass control card identification number.

No default (Integer > 0)

  
HGTYP Hourglass control types. 2
1
Flanagan-Belytschko viscous form (available for both solids and shells).
2 (Default for MAT1/MATS1)
If HGTYP=2 is defined for solids: Puso enhanced assumed strain stiffness form (available only for eight noded CHEXA elements).
If HGTYP=2 is defined for shells: Flanagan-Belytschko stiffness form (available for shells only).
4 (Default for MATHE)
Reese enhanced assumed strain stiffness form (available only for eight-noded CHEXA elements). 2 3
 
HGFAC Scale factor for hourglass control forces.

Default = 0.1 for HGTYP=1 (0.05 < HGFAC < 0.15)

Default = 0.05 for HGTYP=2 (0.0 < HGFAC < 0.1)

Default = 0.01 for HGTYP=4 (0.0 < HGFAC < 0.1)

  

Comments

  1. HOURGLS entries can be selected in element property definition to disable default hourglass control parameters.
  2. HGTYP=1 and HGTYP=2 are available for MAT1/MATS1. For MATHE, only HGTYP=2 and HGTYP=4 are available. In most situations, HGTYP=4 exhibits good performance for MATHE. HGTYP=4 is only available for MATHE materials.
  3. HOURGLS entry when referenced on HGID field of the corresponding PSOLID, PLSOLID, or PSHELL entries will overwrite the values defined via PARAM,HOURGLS.