Hoop stress on the cylinder

[KSR]

sir
We need a clarification regarding the hoop stress and deformation of thin cylinder after mounting a wire over the cylinder surface with the following data.

Tension in the mounting wire = 6 kg.
Cross-section of wire = 2x0.5mm(height & width)
Wire material = steel
Length of the cylinder = 1000 mm
O.D of the cylinder = 1200 mm
Thickness of the cylinder = 20 mm
Cylinder Material = Cast Iron (youngs modulus = 1E5 N/sq.mm,
Poission ratio = 0.23)

After completing various operations the roundness and straightness of the cyl. are within the limits.(less than 0.1mm).
But we are getting a variatoin of 0.1 to 0.15 mm over the cylinder surface after wire mounting. Sir please specify whether the problem is due to hoop stress or other factors like atm. temp. 35-40 degrees celsius , Casting .
Kindly send us your comments at the earliest.
Thanking you

With regards
K.Soundararajan
L.M.W Ltd
Coimbatore-641020
India
E-Mail: lmwrd@md3.vsnl.net.in

 

[prex]

You didn't specify the pitch for winding the wire over the cylinder surface. Also it is unclear what you mean by variation of cylinder surface.
Anyway, if the wire covers entirely the cylinder outer surface and if your variation is a change in diameter, even under these conditions it is difficult to justify such a deformation, though the order of magnitude might be correct. If your variation is a change in length of the outer circumference (but how can you measure it if the outer surface is covered by the wire?), then the value found could be consistent.
As far as temperature changes are concerned you should make the measurements under controlled uniform temperature: here again the order of magnitude is correct, but you need a change in temperature, between the measurement before and after the winding, of some 50 degC to explain your variation.
prex
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