Page 22 - Mechanical Engineer's Data Handbook

STRENGTHS OF MATERIALS 11

where:
k=1500 to 3000; P, is in newtons and D is in
millimetres.

(b) Torque-wrench tightening:
P, = T/0.2D

Shear stress in bolt

Distance of bolt horn edge

I .2.2 Bolted or riveted brackets - stress where: A=bolt area.
in bolts
p2
and similarly a2 = -, etc.
Bracket in torsion A
Shear stress z = P/(nA)
Force on a bolt at rl from centroid of bolt group where: n=number of bolts.
P,=Par,/(r:+r:+r:+. . .)
Vertical force on each bolt P, = P/n
where: n = number of bolts. Maximum tensile stress in bolt at a,, o,,,=~+~,/~? 2
Total force on a bolt P,=vector sum of P, and P,
Shear stress in bolt 7 = PJA (b) Horizontal load:
where: A =bolt area. This is repeated for each bolt and Maximum tensile stress a,,,=a,+P/(nA) for bolt at a,
the greatest value oft is noted.

J ‘Pivot

1.2.3 Bolts in shear

This deals with bolts in single and double shear. The
crushing stress is also important.

Bracket under bending moment Single shear

(a) Vertical load: Shear stress t=4P/7tD2
Tensile force on bolt at a, from pivot point
Double shear
P,=Pda,/(a:+a:+a:+. . .)
Tensile stress o1 = P,/A Shear stress t = 2P/nD2