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sheet metal from volume

Altair Forum User

Hello to all the members,

reading the book “Practical aspects of structural Optimization” I found the following sentence (beginning of pag24):

“We may be asked to design a light weight bracket that has to fit in a 300x300x300mm volume. We want the bracket to be made of steel, to carry a load of 100kg. The maximum permissible deflection of the bracket is 0.1mm and the maximum permissible stress is 20kg/mm^2. We are allowed to use steel that can be 1mm 2 mm or 4mm thick. In this case, our design space would be 300x300x300mm volume. The objective would be to minimize the mass. The optimization constraint would be the permissible stress and deflection. The design variables would be the thickness of the steel and the layout of the steel. (i.e. how the sheet should “flow”- where material should be located – within the design space)”

I don’t really understand how I can set this analysis. How can I ask tell the material to “flow”? Can I define the variable thickness as design variable?

Thanks

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Altair Forum User

Hi Dracu777,

You may consider using discrete DVs for this case. Please refer to DDVAL card for more information on help.

Altair Forum User

Hi Dracu777,

You may consider using discrete DVs for this case. Please refer to DDVAL card for more information on help.

Hello Prakash Pagadala,

thank you for the answer.

I start thinking that in optistruct it is not possible to perform a topology optimization for sheet metal structures. Of course, it is always possible to run a topology optimization and design a welded structure but I haven’t found the way to have the material “flow” like a sheet metal as written in the Altair book.

Optistruct works well when I already have the initial shape of the sheet metal. Topography optimization and size optimization are great tools but, again, I need an initial shape to work on.

If I am wrong, please let me know, because this is the type of problems I have to solve.

Thanks

Rahul_P1

dracu777

The idea behind topology optimization is to give you the load path from a blank design space, you do not need to have the initial shape.

Just see the optistruct example in help -

OptiStruct > OptiStruct Tutorials and Examples > Examples > Example Problems for Topology Optimization:

Suspension Bridge

Altair Forum User

Hi,

Material FLOW in the book may refer to material distribution.

For such problem, I would start with a topology optimization which gives the material distribution (or how sheet flows and defines load path). This is where a concept is generated.

size, shape and/or topography optimization would be followed for further design fine tuning like thickness sizing, etc..

Altair Forum User

Hello,

thank you, both, for your answers.

I found in the same book what I was searching for. 'Available with the SINGLE draw option is a stamping or sheet metal manufactoring constraint. This option forces the evolution of 3D shell interpretable structure from a 3D design domain...'

In which version of Hyperworks did they introduce this new feature?

Thanks

Altair Forum User

Hi,

this feature is available since 11.0.

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