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Understanding DOBJREF in Topology Optimization

Hello everyone,

I am trying ot run a Topology Optimization on a Engine Block.

There are five design spaces in the model wth maufacturing constraints.

Two responses:- Volume Fraction and Frequency.

Csnstraint:- Increasing the 7th mode frequency to 100Hz from 95Hz.

Objective is to minimize Volume Fraction.

Here i am not using min option while creating obejctice, instead i am using minmax option for defining objective.

FOr defining minmax objective i had to create dobjref.

I am getting confused with neg and pos values.

Should i check both the box, what vlaue should i put if i want to minimize vloume fraction.

Please suggest

Regards

Yasir

English

OptiStruct

Hi Yasir,

Please refer to the image from help below:

I think you should leave it to default, unless you need a different factor of the response.

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

Hello Prakash,

Thanks a lot for your response.

I was wondering if i had to minimize the Volume Fraction using dobjref option, while creating the minmax objective.

What values should i enter in the neg and pos boxes.

I always get confused about checking only neg or pos or both and what should be the values.

My aim is to use only 20percent of the total design space volume.

Looking forward to hearing from you.

Regards

Yasir

Hi Yasir,

MinMax will minimize the maximum of the obtained response for volume fraction.

Why don't you give Volume fraction as a constraint instead, if you have a target of 20%?