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Nahid3007

Selection of Best Optimization Algorithm

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Hello community,

 

I got a little bit confused while reading the OptiStruct 2017 User’s Guide.

 

There I found that OptiStruct selects automatically the best optimization algorithm. Five items have been listed there (page 10-11):

- Optimality criteria method

- Convex approximation method

- Method of feasible directions

- Sequential quadratic programming

- Advanced approximations .

 

My question is: Does OptiStruct still selects the Optimality criteria method automatically? And for which type of optimization? There is no information about it in the User’s Guide or Reference Guide.

 

I want to optimize the topology of the 2 dimensional MMB-Beam (see atteched figure). My objective is to minimize compliance subjected to a volume fraction constraint.

 

I found that for my type of problem I shoud use 'OPTMETH=DUAL' since I have a large number of design variable and only one constraint.

 

So I cannot choose the Optimality criteria method in topology optimization?

 

Many thanks in advance

Nahid

 

 

 

 

 

MBB.JPG

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Hi,

 

The default optimization algorithm is known as the Method of Feasible Directions (MFD),

 

From OptiStruct help:

The DUAL algorithm should be used for concept-level optimization (Topology, free-size, and Topography) since such problems typically involve a very large number of design variables.

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Hi,

 

Yes I have already noticed that.

 

But I am still confused whether OptiStuct generally uses the Optimality criteria method or not as mentioned in  2017 User’s Guide (see attached figure)?

 

Regards

Nahid

 

 

 

user_guide.JPG

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On 7/11/2018 at 8:05 AM, Prakash Pagadala said:

HI,

 

I will check and update you soon..

 

Hi,

 

so do you have any updates whether OptiStruct uses the  Optimality criteria method  as mentioned in  2017 User’s Guide?

 

Thank you!

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Hi,

 

OS selects the best algorithm for a given optimization problem. OC might still be activated when the design switch (T0 on PSHELL) is on (no DTPL/DRESP).

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On 7/9/2018 at 8:47 PM, Prakash Pagadala said:

Hi,

 

The default optimization algorithm is known as the Method of Feasible Directions (MFD),

 

From OptiStruct help:

The DUAL algorithm should be used for concept-level optimization (Topology, free-size, and Topography) since such problems typically involve a very large number of design variables.

I am optimizing the radius of the lattice structure. How can I use other optimization algorithms? For example, Method of Feasible Directions (MFD), Adaptive Response Surface Method (ARSM), Genetic Algorithm..., and what is the  default optimization algorithm?Thank you very much!

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