Determine the maximum shear stress:

A beam of triangular cross section of base width 120 mm & height 80 mm is subjected to a shear stress force of 3 kN. Determine the maximum shear stress & the shear stress at the neutral axis.

Solution

Maximum shear stress is at a distance h/2 from the base of the triangle.

Maximum shear stress, τ_max = 3F / bh

τ _max  =  (3 × 3000) / (120 × 80 )= 0.94 N/mm2

Shear stress at the neutral axis,

τ_NA  =  (8/3) ×( F/bh)

= (8/3) × 3000/(120 × 80)

= 0.83 N/mm²