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## Simulation Mechanical and Multiphysics

Distinguished Contributor
Posts: 129
Registered: ‎06-12-2007

# Dry Product Storage Design

118 Views, 2 Replies
03-28-2014 02:11 PM

We are analysing a dry product storage bin with a hopper.

Due to the nature of the product the pressure distribution is not linear, and there is also a vertical traction component due to the product "pulling" on the walls.

I am wondering what the best way to approach a design like this would be.

Ideally we would use some type of variable surface load, and a cylindrical coordinate system. But for whatever reason a critical buckling design scenario cannot be performed with a cylindrical coordinate system.

Right now we are using a spreadsheet to calculate the mean pressure/traction on a particular 11.25 degree section of hopper at different heights to get somewhat accurate results. But we have many loading scenarios, and this is taking a long time to apply all the individual pressures/tractions.

There must be an easier way.

*Expert Elite*
Posts: 574
Registered: ‎08-30-2012

# Re: Dry Product Storage Design

03-30-2014 05:48 PM in reply to: andrewdroth

Hi Andrew,

You should be able to use the variable pressure load ("Setup > Loads > Variable Pressure") and cylindrical coordinate system in a critical buckling analysis. Other types of loads (general constraints, forces, and so on) use a local coordinate system by assigning the coordinate system to a surface or node, and the load applied to the same surface or node follow the local coordinate system. The variable pressure load uses the coordinate system assigned to the load; it does not use the coordinate system that is assigned to the surface.

So although the model uses a coordinate system, the analysis itself does not use the coordinate system. So it should work. Whether the software is programmed to work that way is another issue, but give it a try.

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

Simulation Mechanical user since Dec 1997
Distinguished Contributor
Posts: 129
Registered: ‎06-12-2007

# Re: Dry Product Storage Design

03-31-2014 03:27 PM in reply to: AstroJohnPE

John,

Thank you so much.

We just new local coordinate systems were incompatible with CBL and never tried to do it with variable surface pressure.

This is going to save a lot of time.

Thanks again,

Andrew/