Page 264 - Failure Analysis Case Studies II

249

1
c

73mm
I4 I
76mm
4 -A

As the shaft wheel hub diameter, d = 12 mm, so bending stress,
32M 32~34.4
a=---= = 203 MN/m2.
nd3 H x O.OIZl3

4.2. Torsion due to drive transmission
The electric motor power rating, P = 0.25 kW with an output speed, N = 1500 rpm.
The maximum shaft driven speed, N = 1500 x 16/48 (pulley teeth ratio) = 500 rpm.
250 x 60
-
The maximum applied torque in drive shaft, T = ~ - 4.77 Nm.
500 x 2n
162' 16~4.77
Shear stress due to drive, z = ~ = = 14MN/m2
nd3 7~~0.012~
Consider effect of sudden braking:
0.5 x 3200 X 0.145
Applied torque, T = p- - = 29 Nm
W DwhDcl
=
4 2 4x2
16x29
Shear stress, T = = 85.6 MN/m2.
x 0.0123