Machine Design
Elastic nut is a locking device in which

A slot is cut partly in middle of nut and then slot reduced by tightening a screw
Through slots are made at top and a cotter pin is passed through these and a hole in the bolt, and cotter pin splitted and bent in reverse direction at other end
One small nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming
Hard fibre or nylon cotter is recessed in the nut and becomes threaded as the nut is stewed on the bolt causing a tight grip

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Machine Design
According to I.B.R., when the thickness of boiler shell (t) is greater than 8 mm, then the diameter of rivet hole (d) is obtained by

Equating shearing resistance to the crushing resistance of the rivets
None of these
Equating tearing resistance of the plate to the crushing resistance of the rivets
Equating tearing resistance of the plate to the shearing resistance of the rivets

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