Finding thickness of a cast iron cylinder

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SUMMARY

The discussion centers on calculating the thickness of a cast iron cylinder with a 300mm bore under a pressure of 30 Newtons per square millimetre and a unit working stress of 25 Newtons per square millimetre. The initial calculation by the user, Joe, yielded an incorrect thickness of 180mm. However, upon further analysis and correction, the appropriate formula leads to a thickness of 0.0014mm, indicating a significant misunderstanding of unit conversions and pressure measurements. The correct interpretation of pressure as 30 MPa is crucial for accurate calculations.

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  • Understanding of stress and pressure calculations in engineering
  • Familiarity with the formula for calculating thickness of cylindrical structures
  • Knowledge of unit conversions, particularly between Newtons and megapascals
  • Basic principles of material strength, specifically for cast iron
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  • Explore material properties of cast iron, focusing on stress limits and safety factors
  • Practice similar engineering problems involving pressure and thickness calculations
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joe465
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Homework Statement



A cast-iron cylinder of 300mm bore carries a pressure of 30 Newtons per square
millimetre; what should be its thickness for a unit working stress of 25 Newtons per
square millimetre?

Homework Equations



ó1 = pd/2t

t=pd/2tó1

The Attempt at a Solution



t=pd/2tó1

t= 30*300/2*25

=180mm

Its got to be wrong as its way too big but I am unsure on where I am going wrong, any help would be much appreciated.

'Edit'

ó1/pd=2t

25/(30*3000) = 2t

2t = 0.00277778

t= 0.0014mm (4dp)

Maybes this one, I am not sure.

Thanks, Joe
 
Last edited:
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Your first one should be correct. Considering that the pressure is 30 MPa.
 

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