Snap action of Disc

• Aug 31, 2005

• #2

btrueblood

Mechanical

May 26, 2004

10,033

US

A snap disc has to have a conical or other non-flat shape to it, otherwise it won't snap. The equations you're using assume a flat disc. For a conical disk you can try an analysis using the equations for Belleville washers, see Roark's Formulas for Stress & Strain, Warren C. Young, McGraw-Hill. There are websites out there with Belleville washer formulas on them as well (Google "Belleville Washer").

 

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• Aug 31, 2005

• #3

M

MintJulep

Mechanical

Jun 12, 2003

10,240

JP

Snap-action diaphragms involve buckling. I'm sure their behaviour is well documented.

Timoshenko is the man for bucking of thin sheets, start by looking for stuff from him.

 

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• Aug 31, 2005

• Thread starter
• #4

FEAinfotech

Aerospace

Apr 25, 2005

8

US

The disc dimensions that I have are .003" thick and .5" diameter with a differential pressure of 30 psig.

The disc is pre formed to conical or circular shape with a blister of .375" dia.

You guys still think I should use Belleville Washer design guide lines.

Please let me know.

 

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• Aug 31, 2005

• #5

israelkk

Aerospace

Dec 30, 2002

2,280

IL

FEAinfotech

I have designed and built snap belleville springs for low force 2-12kg and for high forces such as 200kg.

The process is quite complicated because the snap force to one side and the return force are need to be specified and they may not have to be equal. In addition to that the spring deflection between the two stable position is not arbitrary.

One more issue is that the snap forces are highly sensitive to the disk thickness variations. The smaller the thickness the larger the variations.

http://www.webspawner.com/users/israelkk/

 

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