STACK

Bulk Data Entry Defines the stacking information and stacking sequence for ply-based composite definition.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
STACK ID LAM PLYID1 PLYID2 PLYID3 PLYID4 PLYID5 PLYID6  
  PLYID7 etc.              
Optional continuation lines for substack definitions:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
  SUB SID1 SNAME1 SPLYID11 SPLYID12 SPLYID13 SPLYID14 SPLYID15  
    SPLYID16 SPLYID17 etc. etc. etc. etc. etc.  
    etc. etc.            
Optional continuation lines for interface definitions:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
  INT IPLYID11 IPLYID12            
Optional continuation lines for repeat laminate definitions:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
  NRPT NUMBER              

Example 1

Defines a stack consisting of 8 plies with the SMEAR option
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
STACK 1 SMEAR 1010100 1020100 1010200 1020200 1010300 1020300  
  1010400 1020400              

Example 2

Defines a stack with substack and interface information.


Figure 1. Play Layout
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
STACK 2                
  SUB 1 top 11 12 13 14    
  SUB 2 left 21 22 23 24    
  SUB 3 right 31 32 33 34    
  SUB 4 middle 41 42 43      
  INT 14 21            
  INT 14 31            
  INT 21 41            
  INT 43 31            

Definitions

Field Contents SI Unit Example
ID Unique stack identification number.

No default (Integer > 0)

  
LAM Laminate option. The following options are supported:
blank (Default)
All plies must be specified and all stiffness terms are developed.
SYM
Only plies on the bottom half of the composite lay-up need to be specified. These plies are automatically symmetrically reflected to the top half of the composite and given consecutive numbers from bottom to top.
MEM
All plies must be specified, but only membrane terms are developed.
BEND
All plies must be specified, but only bending terms are developed.
SMEAR
All plies must be specified, stacking sequence is ignored, and MID1 is set equal to MID2 on the derived equivalent PSHELL, while MID3, MID4, TS/T, and 12I/T**3 are set to blank.
SMEARZ0
All plies must be specified, stacking sequence is ignored. While the laminate is still considered to be made of homogenized (smeared) material, the effect of offset Z0 is taken into account. Hence, if Z0 ≠ -0.5 * Thick, the equivalent PSHELL will include MID1, MID2 and MID4. MID3 is still set to blank, that is no transverse shear deformation is considered.
SMCORE
All plies must be specified. The last ply specifies core properties and the previous plies specify face sheet properties. The face sheet properties are calculated without regard for stacking sequence; half of the total face sheet thickness is then placed on top of the core, and half is placed on the bottom, to produce a symmetric laminate. Stiffness of the core is ignored while its density is included in inertia calculations.
SYMEM
Only plies on the bottom half of the composite lay-up need to be specified. These plies are automatically symmetrically reflected to the top half of the composite and given consecutive numbers from bottom to top. Only membrane terms are developed for the full laminate.
SYBEND
Only plies on the bottom half of the composite lay-up need to be specified. These plies are automatically symmetrically reflected to the top half of the composite and given consecutive numbers from bottom to top. Only bending terms are developed for the full laminate.
SYSMEAR
Only plies on the bottom half of the composite lay-up need to be specified. These plies are automatically symmetrically reflected to the top half of the composite and given consecutive numbers from bottom to top. Stacking sequence is ignored, and MID1 is set equal to MID2 on the derived equivalent PSHELL, while MID3, MID4, TS/T and 12I/T**3 are set to blank.
  
PLYID# PLY identification.
Integer
Specifies an identification number for the ply.
<String>
Specifies a user-defined string label for the ply. 6

No default (Integer > 0 or <String>)

  
SUB Indicates that substack data is to follow.  
SID# Substack identification number.

No default (Integer > 0)

  
SNAME# Substack user-defined name.

No default (Character)

  
SPLYID# PLY identification number.

No default (Integer > 0)

  
INT Indicates that interface data is to follow.  
IPLYID# PLY identification number.

No default (Integer > 0)

  
NRPT Indicates that repeat laminate data is to follow.  
NUMBER Number of repeat laminates. 5

Default = blank (Integer > 0 or blank)

  

Comments

  1. The STACK card is used in combination with the PCOMPP and PLY cards to create composite properties through the ply-based definition.
  2. Plies are listed from the bottom surface upward, in respect to the element's normal direction, shown in Figure 2.


    Figure 2. (A) Stacking Sequence for a Non-symmetrical Laminate; (B) Stacking Sequence for a Symmetrical Laminate
  3. For convenience, element output for the SMEAR and SMCORE options includes both homogenized shell stresses and individual ply stresses. However, because stacking sequence is ignored in these options, individual ply stresses will only be valid in cases of pure membrane deformation.
  4. Multiple instances of substack and interface continuations are allowed.
  5. The repeat laminates are added to the bottom of the current laminate. Output for repeat laminates are supported in OPTI, H3D, and PUNCH formats.
  6. String based labels allow for easier visual identification of ply entries, including when being referenced in the PLYID# field of STACK entries. For more details, refer to String Label Based Input File in the Bulk Data Input File.
  7. This card is represented as a laminate in HyperMesh.