shear modulus of paper ?

[shearpin]

Hi,
I'm trying to design a die punch for paper (0.020-0.025 thk).
Does somebody have an idea of the shear modulus of paper, or any other value that can help me to calculate the force?

Many thanks in advance for any help.

best regards

 

[IRstuff]

Have you tried getting a paper hole puncher and making some measurements?

TTFN

 

[Sparweb]

The paper punch I have on my desk has a lever 4" from the fulcrum, and the punch pin is 0.45" from the fulcrum, giving a force amplification factor of about 8.9. If my hand pushes down with about 40 pounds of force to get the punch through a 3/16" stack of paper, then the shear force is 356 pounds, and the shear stress on the two 9/32" pins is:

356/(pi*9/32"*3/16"*2) = 3371 psi

That seems high... something to start with at least.


STF

 

[brad]

I would venture to guess that for most paper punches, the internal frictional forces are greater than whatever force is needed to shear the paper. Hence using this would result in excessive estimates for the shear value (as SparWeb observes above).

Balsa wood has a tensile strength of @ 3 MPa (450 psi) perpendicular to grain. This is the closest relevant information I readily found.

Brad

 

[TheTick]

It's a longshot....

Institute of Paper Chemistry

http://www.ipst.edu/

I may make you feel, but I can't make you think.