Laminates

Laminate entities define the list of stacked plies which make up a laminated structure.

Laminate Types and Options

Additional options include control of symmetry so that only half of the plies need to be created (all solvers) and analysis methodology which manipulates how the ABD matrix is calculated (OptiStruct only).

There are three types of laminates:
Ply Laminates
Used to model parts which do not have T junctions. Typical examples are flat or curved panels.
Sublaminates
Used to model portions of a part with complex geometry like T junctions. Examples are the caps and webs of an I-beam.
Interface Laminates
Used to join the sublaminates of a part with complex geometry.
The items in the following table comprise laminate data.
Option Description
Name Name of the laminate.
Card Image STACK if user profile is OptiStruct. /STACK if user profile is Radioss. None for other solvers.
Type Controls laminate symmetry. Additionally, manipulates laminate ABD calculations (OptiStruct only).
Total
All plies must be specified, and all stiffness terms are developed.
Membrane
All plies must be specified, but only membrane terms are developed.
Bending
All plies must be specified, but only bending terms are developed.
Smear
Effects of stacking sequence are removed by setting B = 0 and D = [A]*(T^2)/12.
Smear Core
The last ply in the stack specifies the core. Plies above specify the face sheet. Stiffness of the core is ignored. Stiffness of the face sheet is calculated using the Smear calculations described above. Half the thickness of the face sheet is placed above the core and half is placed on the bottom to produce a symmetric laminate.
Symmetric
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.
Symmetric Membrane
Only plies on the bottom half of the stack need to be specified. Only membrane terms for the full laminate are developed.
Symmetric Bending
Only plies on the bottom half of the stack need to be specified. Only bending terms for the full laminate are developed.
Symmetric Smear
Only plies on the bottom half of the stack need to be specified. Stiffness is then calculated using the Smear calculations described above.
NRPT Number of repeats for plies in laminate.

Ply Laminates

Ply laminates define the stacking sequence of ply entities on flat and curved composite structures.

The stack direction for the plies of a ply laminate is in the direction of the element's normal.

The following image displays ply laminate stacking in the Composite Browser.
Figure 1.


The following image displays the ply laminate stacking direction.
Figure 2.


Sublaminates

Sublaminates define the stacking sequence of ply entities on a portion of a model with complex geometry.

The stack direction for the plies of a sublaminate is defined by an interface definition within an associated interface laminate. Note until the sublaminate is added to an interface laminate, the stack direction is arbitrary.

The following image displays a sublaminate ply sequence.
Figure 3.


Interface Laminates

Interface laminates are used to define complex laminated structures that wrap around corners.

Interface laminates specify how the sublaminates of the structure are joined.

The stack direction for the sublaminates of an interface laminate is in the direction of the element's normal. An interface within an interface laminate defines which plies of two sublaminates touch, or interface, with each other. The exact stacking sequence of the plies of the sublaminates is determined by which two plies of the sublaminates are specified in the interface.

Each sublaminate stacked within an interface laminate must have at least one interface definition.

The following image displays an interface laminate definition for a typical T junction.
Figure 4.


Supported Solver Cards

Solver cards supported by the laminate entity.

The following table lists each solver card along with its supported laminate entity.
Solver Card Laminate Entity
Abaqus None. A template property (*SHELL SECTION COMPOSITE or *SHELL GENERAL SECTION) should be assigned to all elements in composite part. Upon laminate realization, the attributes of the template property are passed to all generated zone properties. The laminate name will populate the LAYUP attribute of each property.
ANSYS None. A template property (SECTYPE SHELL) should be assigned to all elements in a composite part. Upon laminate realization, the attributes of the template property are passed to all generated zone properties.
LS-DYNA None. A template property (*PART COMPOSITE on HyperMesh Component entity) should collect all elements in a composite part. Upon laminate realization, the attributes of the template property are passed to all generated zone properties.
Nastran PCOMPP (Option to realize to PCOMPG or PCOMP). Upon laminate realization, the attributes of the template property are passed to all generated zone properties.
OptiStruct PCOMPP
PAM-CRASH None. Ply entities stacking in Laminate with card image LAYER/ will be assigned to the Material 131 of the composite part.
Radioss
  • LAM_STACK – automatically generates /PROP/PCOMPP upon creation
  • P17_STACK – automatically generates /PROP/STACK upon creation
  • P51_STACK – automatically generates /PROP/TYPE51 upon creation