When a cantilever beam is subjected to a point load which is directed vertically upwards at its free end, the maximum compressive stresses will be developed at __________.

Explanation:

Nature of Bending stress:

(i) Cantilever beam: 

Case 1)

• When a cantilever beam is subjected to a hogging bending moment (load acting downwards). Then cross-section above the neutral axis (NA) is subjected to tensile stresses and the cross-section below the neutral axis (NA) is subjected to compressive stress.

Case 2)

• When a cantilever beam is subjected to a sagging bending moment (load acting upwards). Then cross-section above the neutral axis (NA) is subjected to compressive stresses and the cross-section below neutral axis (NA) is subjected to tensile stress.

(ii) Simply supported beam: When simply supported beam is subjected to sagging bending moment, cross-section above NA is subjected to compressive stresses and cross-section below neutral axis is subjected to tensile stress. 

From above two concept it is clear that:

(i) The bending stress is zero at neutral axis

(ii) The bending stress in the rectangular beam section varies linearly.

(iii) When a cantilever beam is loaded vertically downwards at its free end, maximum compressive stress will develop at bottom fibre.