Calculation of surface strains on a plate in shear

[Frankbroadanddeep]

My problem today is how to calculate the surface strains on a plate in shear.

I am considering designing a load cell device which has a vertically mounted thin plate approximately 1" square by 20 thou ( 25 x 25 x 0.5 mm ).

The plate is grounded on one vertical side and a weight of up to 5 lb ( 2 kg ) on the other. The plate is therefore in shear when the weight is attached. I need to know what shear strains I could expect from these conditions. My only varaible which I can change is the thickness of the plate. I need to keep the strain down to less than about 1% to avoid permanent deformation.

 

[ishvaaag]

This problem of a short cantilever for a rectangular plate with a tip load is solved in theory of elasticity, most texts solving for stresses. I think even 2 months ago found solved the thing in the web. You then can use the stress-strain relationships to solve for the strains.

You can find, I think, free tools for both tasks in the Mathcad collaboratory.