PCOMPG

Format

Example

Definitions

Comments

1. String based labels allow for easier visual identification of properties, including when being referenced by other cards. (For example, the PID field of elements). For more details, refer to String Label Based Input File in the Bulk Data Input File.
2. TREF specified on the PCOMPG entry overrides reference temperatures given for individual ply materials. If TREF is not specified (blank) on the PCOMPG card, then all the ply materials must have the same reference temperature.
3. For SOUTi to take effect, CSTRESS must be requested in the I/O Options section of the input deck. Individual ply results will be available in addition to shell stresses and strains based on the homogenized composite properties.
4. An additional piece of information available with ply results is "failure index for the element", which is the maximum of failure indices for individual plies in this element. Only the plies with SOUTi set to YES are considered in the evaluation of this maximum.
5. If all plies specify zero transverse shear coefficients (G1Z, G2Z on MAT8 card, isotropic G for MAT1, not available for MAT2), the in-plane shear modulus will be used to determine transverse shear stiffness of the composite.
   Note: If just one layer has a nonzero value specified for transverse shear modulus, this substitution is not being performed, and user-specified values are being used for all plies.
6. The signs given to stress limits for compression and tension (ST, SC, for MAT1; Xt, Xc, and so on for MAT8) are of no relevance. Absolute values are taken and used in the appropriate context to calculate failure indices.
7. For composites with offset (Z0 ≠ 0.5 * Thickness), correct values of shell stresses for the bottom and top surfaces of the shell are produced.
   Note: These shell stresses are calculated using homogenized shell properties, and should be interpreted with caution.
8. For composites with offset (Z0 ≠ 0.5 * Thickness) the buckling results will not be correct. This is because the membrane-bending coupling resulting from composite offset is not included in the differential stiffness matrix. Therefore, the preferred method of incorporating offset in buckling analysis is the element offset ZOFFS.
9. Element GRID thicknesses cannot be defined for elements that reference PCOMPG data.
10. Plies are listed from the bottom surface upwards, in respect to the element's normal direction.

    
    
    Figure 1. Stacking Sequence for a Non-symmetrical Laminate

11. If GE is specified on the PCOMP entry as a Real number, it will be used for the element, and the values supplied on material entries for individual plies are ignored. With USEMAT in this field, GE coefficients from ply material data will be used to calculate damping matrices for the composite. These matrices will, in general, be different for membrane, bending and shear states.
12. To obtain the damping coefficient GE, multiply the critical damping ratio $C/C_0$ by 2.0.
13. The global ply identification number must be unique with respect to other plies in the entry.
14. 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.
15. Hill's failure theory does not differentiate between compressive and tensile strength. While different values of respective strength limits are accepted, it is still recommended that Xt is set to be equal to Xc, and Yt is set to be equal to Yc when this criteria is used. Xt and Xc are allowable tensile and compressive stresses in the principle x direction of the material. Yt and Yc are allowable tensile and compressive stresses in the principle y direction of the material.
16. Failure index calculation according to Maximum Strain Theory is based on mechanical component of strain only, not on total strain. This is because only the mechanical strain contributes to actual damage of the respective ply (pure thermal expansion produces no damaging effects).
17. According to the formula, some failure criteria (for example, Tsai-Wu and Hoffman) would produce a negative ply failure, depending on the problem.
18. If PARAM, SRCOMPS,YES is added to the input file, strength ratios with respect to designated failure theory are output for composite elements that have failure indices requested.
19. The following two formats are permissible for the Z0 field:

    Real Number:

    It represents the distance from the shell element reference plane to the bottom surface of the shell (Default = -0.5 * Thick, Thick being the composite total thickness (Real or blank)).

    Surface:

    Top:

    The shell reference plane, the plane defined by the grid points, and the top surface of the shell are coplanar.

    This makes the effective "Real" Z0 value equal to the composite total thickness (-1.0 * Thick). See Figure 2.

    
    
    Figure 2. Top Option for Z0

    Bottom:

    The shell reference plane, the plane defined by the grid points, and the bottom surface of the shell are coplanar.

    This makes the effective "Real" Z0 value equal to 0. See Figure 3.

    
    
    Figure 3. Bottom Option for Z0

    Automatic offset control is available for ply thickness (size) optimization and for free-size optimization, where the specified offset values are automatically updated based on thickness changes. For free-size optimization, such an automatic offset, is only applicable when Z0=0.0 or BOTTOM.

20. The material parameters, Xt, Xc, Yt, Yc, and S on the MAT8 Bulk Data Entry should be specified for failure criteria calculation.
21. Small Displacement and Large Displacement Nonlinear Static Analyses are supported with Composites using PCOMP, PCOMPP, and PCOMPG entries.
22. The repeat laminates are added to the bottom of the current laminate. Output for repeat laminates are supported in OPTI, H3D, and PUNCH formats.
23. This card is represented as a property in HyperMesh.