Necessary Compression Force

[teilhardo]

Hi,

This seems to be a deceptively simple question, but I am trying to calculate the change in height of an aluminum "dish" with a "lip" that is .10mm tall with an OD of 15.50mm and an ID of 15.00mm. It is made from a .50mm disc with OD of 15mm, so the base is .40mm thick.

I have calculated that the surface area of the lip is around 12mm^2 and I am looking to find the force that must be imparted perpendicular to the "lip" surface such that it is flush with the bottom of the "dish". I have scoured the internet trying to find the way of going about this calculation but I am coming up short.

Does anybody have any ideas?

Thanks,
Tei

 

[Engdoitbetter]

Hi teilhardo,

I think you should post a sketch to improvue our understanding of the situation.

Thanks in advance

 

[teilhardo]

Hi,

Thanks for the reply. I am attaching a diagram for you to reference. The force is perpendicular to the top plane of the "dish".

Thanks,
Tei

 

[Engdoitbetter]

At first, since the decrease in height required is not negligible compared to total height, I would say that you cannot obtain a flat dish without permanent deformation (i.e. you have to load the material beyond yield strength).
You may consider a small part of the lip similar to a beam, however I think that the surrounding material (the bottom of the dish and the lip itself) may increase the load required due to their stiffening effect. In addition, it is possible that the lip undergoes buckling before actually being flush with the bottom.

These are my first impressions.
Hope it helps.

Stefano

 

[teilhardo]

HI Stefano,

Would there be an equation that I could use to calculate this permanent height difference (even with buckling)?

Thanks,
Tei

 

[BrianE22]

Looks like a "Dome Switch". You might find some info from the vendors that make those.

 

[Engdoitbetter]

Maybe these links will help you, especially the second:

http://www.me.iitb.ac.in/~ramesh/ME649/Forming_2.pdf

http://www.me.iitb.ac.in/~ramesh/ME649/Forming_3.pdf

 

[teilhardo]

Thank you very much. I will begin to start reading them!