What is shear as in in shear stress is it the cutting away of an rod shaft or what?

Tensile stress is this like pulling stress then?

Calculate the thickness t and width b of a cotter used in conjunction with a rod of diameter d

Let ft tensile stress
fs shear stress
fc crushing stress

Assume failure to occur due to

a tearing at the section through the cotter

Load P = pidpower2/4 - dtxft

b shearing of the cotter double shear

Load p = 2xbxtxfs

c Crushing of the cotter

Load P = dxtxfc

If the material is mild steel shear stress may be taken as 4/5 tensile stress and crushing stress as twice tensile stress

So shear stress may be taken as four fifths of tensile stress is that right?

fs = 4/5xft and fc = 2xft

for equal strength equate b and c

2xbxtxfs = dxtxfc
2xbxtx4/5xft = dxtx2ft
b = 10/8xd = 1.25d

from which equating a and c pixdpower2/4-dxtxft=dxtxfc

from which t = pixd/12 = 0.26d.

However is it just us or does 3.1416x1.25/12 not equal = 0.33 how did the course text get 0.26 then?

It has fs=4/5xft that is 4/5 x ft but what is 4/5 how is this worked out on a calculator? As in 4
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also what is 10 how is this worked out on a calculator

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