NX Nastran Optimization - How do I know what element properties can be design variables?

[ZeroExperience]

In NX Nastran

For a PBEAM, what can i vary? Area, I1, I2, etc?

For a PCOMP, what can I vary, Z0, NSM, SB, TREF, GE?

 

[BlasMolero]

Dear ZeroExperience,
Design variables in NX NASTRAN (DESOPT SOL200) are independent quantities that the solver can vary to achieve the optimum design. Upper and lower limits define the allowable range of variation. For example, you can define a variable to modify shell thickness between 0.001 mm and 10 mm from a starting thickness of 0.15 mm.

You can define four types of design variables:

1.- Property:
This type lets you choose physical properties, such as the T field (thickness) in a PSHELL, the DIM1 in a PBEAML, and so on. In NX Nastran, this creates a DESVAR and DVPREL1 combination. The following physical property types are supported:

2.- Composite Property:
This type lets you choose composite or laminate physical properties such as the NSM field (nonstructural mass) in a PCOMP. In NX Nastran, this creates a DESVAR and DVPREL1 combination. You can specify a type of PCOMP or Laminate. The following property fields are supported:

Z0 GE
NSM T
SB THETA
TREF

If you select T or THETA, you must specify whether the design variable affects a Single Ply or Multiple Plies.

If you select Multiple Plies, the thickness or the orientation angle of the selected plies (specified by material ID in the Plies list) will vary with the same ratio as the design variable changes. For example, if the design variable change is 2.0, the thickness or the orientation angle will be doubled for all the selected plies.

Also, when you select T or THETA, you can select Include Reference Plane to Bottom Fiber Distance (Z0) to make sure that a specific relation DVPREL1 is written out at export for the Z0 field in the PCOMP property. The DVPREL1 card is written out only if Z0 represents the middle or top plane of the composite. If Z0 is 0.0 (equivalent to bottom), the relation is not needed. If Z0 is user-defined, an error message is issued at export. For more information, see Design Optimization with Composite Materials in the NX Nastran Design Sensitivity and Optimization User’s Guide

3.- Material:
This type lets you choose material properties such as the Young's Modulus value in a MAT1 material. In NX Nastran, this creates a DESVAR and DVMREL1 combination. The following material types and properties are supported:

MAT1: E, G, NU, RHO, A, TREF, GE
MAT2: G11, G12, G13, G22, G23, G33, RHO, A1, A2, A3, TREF, GE
MAT8: E1, E2, NU12, G12, G1Z, G2Z, RHO, A1, A2, TREF, XT, XC, YT, YC, S, GE
MAT9: G11, G12, G13, G14, G15, G16, G22, G23, G24, G25, G26, G33, G34, G35, G36, G44, G45, G46, G55


4.- Connectivity (fields in the element definition):
This type lets you choose element fields such as the ZOFFS field (Z offset) in a CQUAD4 element. In NX Nastran, this creates a DESVAR and DVCREL1 combination. Fields on the following element types are supported:

CBAR: X1, X2, X3, W1A, W2A, W3A, W1B, W2B, W3B
CBEAM: X1, X2, X3, W1A, W2A, W3A, W1B, W2B, W3B
CBUSH: X1, X2, X3, S, S1, S2, S3
CDAMP2: B
CELAS2: K, GE, S
CGAP: X1, X2, X3
CMASS2: M
CONM1: M11, M21, M22, M31, M32, M33, M41, M42, M43, M44, M51, M52, M53, M54, M55, M61, M62, M63, M64, M65, M66
CONM2: M, X1, X2, X3, I11, I21, I22, I31, I32, I33
CONROD: A, J, C, NSM
CQUAD4: THETA, ZOFFS, T1, T2, T3, T4
CQUAD8: THETA, ZOFFS, T1, T2, T3, T4
CQUADR: THETA, ZOFFS, T1, T2, T3, T4
CTRIA3: THETA, ZOFFS, T1, T2, T3
CTRIA6: THETA, ZOFFS, T1, T2, T3
CTRIAR: THETA, ZOFFS, T1, T2, T3



Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

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