Selection of Best Optimization Algorithm

Nahid3007

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

 

 

 

 

 

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

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.

Nahid3007

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

 

 

 

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

HI,

 

I will check and update you soon..

Nahid3007

Altair Forum User 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!

Altair Forum User

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).

Altair Forum User

Altair Forum User 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!