Users:Structural Optimization/Design Variables/Nodal Coordinates

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|OPT-BOUND ''ID''
 
|OPT-BOUND ''ID''
 
|Linking to a bound defined in BOUND block.
 
|Linking to a bound defined in BOUND block.
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Remark: only SCALAR_BOUND is valid.
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Remark: for valid bounds refer to the variable bounds section
 
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|-
 
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<pre>
 
<pre>
 
OPT-VAR 1
 
OPT-VAR 1
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  TYPE=NODE 100 SUBTYPE=THICKNESS BOUND=OPT-BOUND 1
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  TYPE=NODE 100 SUBTYPE=DIR BOUND=OPT-BOUND 1
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  TYPE=ND-SET 2 SUBTYPE=THICKNESS BOUND=OPT-BOUND 1
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  TYPE=ND-SET 2 SUBTYPE=XYZ BOUND=OPT-BOUND 1
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TYPE=ND-SET 3 SUBTYPE=VEC D1=0.0 D2=0.0 D3=1.0
 
</pre>
 
</pre>
  
 
== A complete test example ==
 
== A complete test example ==
  
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TODO
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=== Model description ===
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This example considers the thickness optimization of the Kresge auditorium. In a first step, the shape of the auditorium was optimized for minimal strain energy under dead load (cfr. PhD M. Firl) with constant thickness. The resulting shape is presented in the figure. In a second step, the thickness of the optimized shape is optimized. Strain energy under dead load is again used as the objective function. The design variables are the thicknesses at every node, constrained between 0.10 and 0.03 m. The shape of the shell is fixed.
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                                                                  [[File:shape.jpg |400px]]
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=== Results ===
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In the figures, the thickness distribution and the Von Mises stresses in the top plane are shown for 50 optimization steps starting from a constant thickness of 0.05 m. It is clear that the largest part of the shell works very efficient on membrane forces and thus the thickness can be the minimal thickness. Only the support regions are subjected to bending, so the stresses can be reduced significantly by increasing the thickness to the maximal thickness. 
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[[File:MIT_objSE_thickness.gif| Thickness]]
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[[File:MIT_objSE_vmtop.gif | Von Mises top]]
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=== Input File ===
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to be added
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Latest revision as of 11:37, 8 December 2016


Contents

General Description

Short Info

With this design variable, the nodal coordinates (shape of the structure) can be optimized.

There are different modes to define how the shape is allowed to change -> SUBTYPES

Parameters in the Input File

Compulsory Parameters
Parameter Values, Default(*) Description
TYPE NODE ID, ND-SET ID Linking to previously defined nodes or node sets
SUBTYPE VEC D1=X D2=Y D3=Z change of coordinate in defined direction
SUBTYPE DIR change of coordinate in direction of nodal director (changing during optimization)
SUBTYPE FIXED_DIR change of coordinate in direction of initial nodal director (constant during optimization)
SUBTYPE XYZ change of coordinate in x,y and z direction (3 individual variables per node)
SUBTYPE PLANE change of coordinate in plane of initial configuration (constant during optimization)
Optional Parameters
Parameter Values, Default(*) Description
BOUND OPT-BOUND ID Linking to a bound defined in BOUND block.

Remark: for valid bounds refer to the variable bounds section


Example of a Complete Input Block

This design variable can be defined for one node of for a nodal set. It is good practice to add a bound to the thickness design variables to avoid unrealistic values. In general, it is obvious to choose an upper and lower limit. Since the thickness is a scalar design variable, only SCALAR_BOUND is appropriate. 

OPT-VAR 1
 TYPE=NODE 100 SUBTYPE=DIR BOUND=OPT-BOUND 1
 TYPE=ND-SET 2 SUBTYPE=XYZ BOUND=OPT-BOUND 1
 TYPE=ND-SET 3 SUBTYPE=VEC D1=0.0 D2=0.0 D3=1.0

A complete test example

TODO





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