Question

If the angle of contact is greater than 60 degrees, then unit pressure normal to the surface of contact is __________

(a) Less at the ends than at the centre

(b) More at the ends then centre

(c) Remains equal at the ends and the centre

(d) Remains unaffected

The question was asked by my school principal while I was bunking the class.

The doubt is from Brakes in division Brakes and Dynamometers of Machine Dynamics

Answer 1

When the angle of contact is greater than 60 degrees, the unit pressure normal to the surface of contact is more at the ends then centre. The correct answer is (b) More at the ends then centre.

In brake and contact stress analysis, when the contact angle exceeds 60 degrees, the pressure distribution becomes non-uniform due to the geometry and deformation characteristics of the contact surfaces. The pressure concentration occurs at the ends of the contact zone rather than at the centre.