Rule 1: For every calculated
normal stress there is a corresponding induced shear stress; the value of the shear
stress is equal to half that of the normal stress.
Rule 2: For every calculated shear stress
there is a corresponding induced normal stress; the value of the normal stress is equal to
that of the shear stress. The tables of combined stress formulas, below, include equations
for calculating both maximum nominal tensile or compressive stresses, and maximum
nominal shear stresses.
Maximum Nominal
Tensile or Compressive Stress
Maximum Nominal
Shear Stress
Where:
L = 
Length of Beam 
inches 
(mm) 
h = 
Height of Beam 
inches 
(mm) 
b = 
Width of Beam 
inches 
(mm) 
F_{y} = 
Applied Load 
lbs 
(N) 
F_{x} = 
Applied Load 
lbs 
(N) 
σ' _{a} = 
Stress, Tensile or Compressive 
Lbs/in^{2} 
(N/mm^{2)} 
σ' _{b} = 
Stress, Tensile or Compressive 
Lbs/in^{2} 
(N/mm^{2)} 
τ'_{a} = 
Stress , Max. Nominal Shear 
Lbs/in^{2} 
(N/mm^{2)} 
τ'_{b} = 
Stress , Max. Nominal Shear 
Lbs/in^{2} 
(N/mm^{2)} 
References:
 Any Machinery's Handbook published since 1931 or,
 Machinery's Handbook, 21st Edition, Page 404 or,
 Machinery's Handbook, 23st Edition, Page 260 or,
 Machinery's Handbook, 27st Edition, Page 261
