PCOMP – Composite Laminate Property
Defines the structure and properties of an n-ply composite laminate material.
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PCOMP |
PID |
Z0 |
NSM |
SB |
FT |
TREF |
GE |
LAM |
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MID1 |
T1 |
THETA1 |
SOUT1 |
MID2 |
T2 |
THETA2 |
SOUT2 |
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MID3 |
T3 |
THETA3 |
SOUT3 |
etc. |
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DS |
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(2) |
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(6) |
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(10) |
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PCOMP |
100 |
-0.5 |
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1.E5 |
STRN |
100. |
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120 |
0.2 |
0.0 |
YES |
120 |
0.6 |
0.0 |
NO |
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120 |
0.2 |
0.0 |
YES |
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1.0 |
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Field |
Contents |
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PID |
Unique composite property identification number. No default (Integer > 0) |
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Z0 |
Distance from the shell element reference plane to the bottom surface. Default = -0.5* Thick, Thick being the composite total thickness (Real or blank) |
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NSM |
Nonstructural mass per unit area. No default (Real) |
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SB |
Allowable interlaminar shear stress (shear stress in the bonding material). Disregarded if blank or 0.0. No default (Real ³ 0.0) |
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FT |
Failure theory code. If blank, no failure calculations are performed. The following failure theory codes are supported: HILL for Hill theory, HOFF for Hoffman theory, TSAI for Tsai-Wu theory, STRN for Maximum Strain Theory. Default = no failure calculations are performed (HILL, HOFF, TSAI, or STRN) |
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TREF |
Reference (stress free) temperature. See comment 1. Default = 0.0 (Real) |
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GE |
Damping coefficient. See comments 10 and 11. Default = 0.0 (Real) |
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LAM |
Laminate option. If blank, all plies must be specified and all stiffness terms are developed. The following options are supported: 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 zero. 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 zero. Default = blank, i.e. all plies must be specified (SYM, MEM, BEND, SMEAR, SYMEM, SYBEND or SYSMEAR) |
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MIDi |
Material IDs of individual plies. The plies are identified by consecutively numbering them from 1 at the bottom layer. The MIDs must refer to MAT1, MAT2 or MAT8 bulk data entries. If MIDi is not specified, default is the last defined MIDi. Default = last defined MIDi (Integer>0 or blank, except that MID1 must be specified) |
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Ti |
Thicknesses of individual plies. If Ti is not specified, default is the last defined Ti. Default = last defined Ti (Real ³ 0.0 or blank, except that T1 must be specified) |
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THETAi |
Orientation angle, in degrees, of the longitudinal direction of each ply relative to the x-axis of the material coordinate system associated with a given element. If no material coordinate system is prescribed for the element, the angle is measured relative to side 1-2 of this element. Default = 0.0 (Real or blank) |
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SOUTi |
Stress, Strain and Failure Index output request for individual plies. See comments 2 and 3. Default = NO (YES or NO) |
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DS |
Design switch. If non-zero (1.0), the elements associated with this PCOMP data are included in the topology design volume or space. Default = blank (Real = 1.0 or blank) |
TREF specified on the PCOMP entry overrides reference temperatures given for individual ply materials. If TREF is not specified (blank) on the PCOMP card, then all the ply materials must have the same reference temperature.
Stress, Strain and Failure Index output for individual plies is activated by setting SOUTi to YES for a given ply. In addition, the I/O Options CSTRESS (controlling Stress and Failure Index output) and/or CSTRAIN (controlling Strain output) must be defined. Failure Index output also requires that the FT and SB fields be defined and that stress/strain allowables on the referenced materials are defined.
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. Note that only the plies with SOUTi set to YES are considered in the evaluation of this maximum.
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 non zero value specified for transverse shear modulus, this substitution is not being performed, and user-specified values are being used for all plies.
The signs given to stress limits for compression and tension (ST, SC, for MAT1; Xt, Xc, etc. for MAT8) are of no relevance. Absolute values are taken and used in the appropriate context to calculate failure indices.
For composites with offset (Z0 ¹ 0.5 * Thickness) OptiStruct produces correct values of shell stresses for the bottom and top surfaces of the shell.
Note: these shell stresses are calculated using homogenized shell properties, and should be interpreted with caution.
For composites with offset (Z0 ¹ 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. Hence, the preferred method of incorporating offset in buckling analysis is the element offset ZOFFS.
Element GRID thicknesses cannot be defined for elements that reference PCOMP data.
Plies are listed from the bottom surface upwards, in respect to the element’s normal direction. In the image below, (a) shows the stacking sequence for a non-symmetrical laminate, and (b) shows the stacking sequence for a symmetrical laminate.
GE given on the PCOMP entry will be used for the element, and the values supplied on material entries for individual plies are ignored. The user is responsible for supplying the equivalent damping value on the PCOMP entry.
To obtain the damping coefficient
GE, multiply the critical damping ratio 
by 2.0.
Go To
Guidelines for Bulk Data Entries
Alphabetical List of Bulk Data Entries