This document contains 3 engineering design problems involving calculations to determine the necessary dimensions of mechanical components based on given load and stress criteria: 1) Calculate the diameter of a connecting rod given a load of 65kN and maximum tensile stress of 35N/mm^2. 2) Find the minimum punch diameter for a hole in a 20mm thick steel plate under a 380kN force and 300N/mm^2 ultimate shear strength. 3) Determine the suitable diameter of a single eye end on a tractor trolley under a 25kN load based on a maximum bearing pressure of 12N/mm^2.

1. 22565 EMD : 1.2 : Fundamental of Design
1) A steam engine circular connecting rod is subjected to a
maximum load of 65 kN. Find the diameter of the connecting rod
at its thinnest part, if the permissible tensile stress is 35 N/mm2.
Data given Load = 65 KN Permissible tensile stress = 35 N/mm2
Find diameter ‘d’ = ?
 = Force / C. S. Area
C. S. Area =  / 4 x d2
35 N/mm2 = 65 x 1000 N / Area
Area = 65000 / 35 = 1857.42
 / 4 x d2 = 1857.42
d = 48.63mm  50mm
65 KN

2. 22565 EMD : 1.2 : Fundamental of Design
2) Find the minimum size of a hole that can be punched in a 20
mm thick mild steel plate having an ultimate shear strength of 300
N/mm2. Force of 380KN is applied on the plate.
Data : t = Plate thickness =20mm Force = F =380KN
 = Ultimate shear strength = 300 N/mm2
 = Force / Area
Area = Perimeter x thickness
Area = 2 x  x R x t
300 N/mm2 = 380 x 1000 N / 2 x  x R x 20
R = radius of hole = 10 mm
Therefore punch diameter of hole is = 20mm

3. 22565 EMD : 1.2 : Fundamental of Design
3) A single eye end of the tractor trolley is shown in figure
subjected to load of 25KN having maximum bearing pressure
capacity of 12N/mm2. Find suitable diameter considering failure
under crushing. Thickness of single eye is 40mm.
Data : Force = 25KN, thickness =t =40mm
Pb = Bearing pressure = 12 N/mm2
Area under crushing = d x t
Pb = Force / Area
12 N/mm2 = 25 x 1000 / d x 40mm
d= 52.08  53mm
t
d
F