Thick Cylinder Mechanics Quiz
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Px = radial pressure at radius ‘x’ and px+dpx = radial pressure at radius ‘x+dx’, where dpx = change in radial pressure over ‘dx’ thickness. Consider failure of a thin ring having radius ‘x’ and thickness ‘dx’. Bursting force = pressure x projected area of the ______ surface onto horizontal plane.

curved

For equilibrium, Bursting force = Resisting ______.

force

Lame’s equations for radial pressure and Hoop ______ apply to thick cylinders.

stress

The outer radius is denoted as ______ and the inner radius as r2.

<p>r1</p> Signup and view all the answers

Boundary conditions specify that at radius x = r2, radial pressure px = ______.

<p>pi</p> Signup and view all the answers

Maximum hoop stress occurs at the ______ surface of the thick cylinder.

<p>inner</p> Signup and view all the answers

Longitudinal stress is caused by the force exerted by fluid pressure on the ______ of the thick cylinder.

<p>lids</p> Signup and view all the answers

Lame’s constants help determine the values of stresses and ______ in thick cylinders under internal or external pressure.

<p>pressures</p> Signup and view all the answers

The radial stress will be ______.

<p>compressive</p> Signup and view all the answers

To join the maximum hoop stress point and minimum hoop stress point defines the ______.

<p>curve</p> Signup and view all the answers

A thick cylinder subjected to external fluid pressure will have hoop, radial, and longitudinal stresses that are ______.

<p>compressive</p> Signup and view all the answers

The numerical difference between maximum and minimum hoop stresses in a thick cylinder is equal to the numerical difference of internal and ______.

<p>external fluid pressure</p> Signup and view all the answers

When a thick cylinder is subjected to internal fluid pressure only, hoop stress and longitudinal stress are ______.

<p>tensile</p> Signup and view all the answers

Lame’s constants A and B are positive when the thick cylinder is subjected to ______ fluid pressure only.

<p>internal</p> Signup and view all the answers

Volumetric strain in a thick cylinder refers to the ______ stored in the thick cylinder.

<p>fluid</p> Signup and view all the answers

The change in storage capacity of the thick cylinder can be calculated using the ______.

<p>volume</p> Signup and view all the answers

The Young's modulus of elasticity for the cylinder material is ______ GPa.

<p>200</p> Signup and view all the answers

Poisson's ratio of the cylinder material is ______.

<p>0.3</p> Signup and view all the answers

The internal fluid pressure acting at the inner radius r2 is ______ MPa.

<p>8</p> Signup and view all the answers

The outer radius of the cylinder is ______ mm.

<p>240</p> Signup and view all the answers

When the ends of the thick cylinder are closed, the longitudinal stress is ______ MPa.

<p>6.4</p> Signup and view all the answers

The change in wall thickness when the ends are closed is ______ mm.

<p>0.003968</p> Signup and view all the answers

When the ends of the cylinder are opened, the change in wall thickness is ______ mm.

<p>0.0032</p> Signup and view all the answers

Lame's constant A has a value of ______.

<p>6.4</p> Signup and view all the answers

Longitudinal stress is the same at any point in the thick ______.

<p>cylinder</p> Signup and view all the answers

The internal diameter of a thick cylinder is ______ mm.

<p>160</p> Signup and view all the answers

The radial stress is always ______ and its magnitude is equal to radial pressure.

<p>compressive</p> Signup and view all the answers

The external diameter of the thick cylinder is ______ mm.

<p>200</p> Signup and view all the answers

The internal fluid pressure acting on the cylinder is ______ MPa.

<p>12</p> Signup and view all the answers

At any point in the thick cylinder, the algebraic sum of the hoop stress and radial stress is equal to ______.

<p>2A</p> Signup and view all the answers

Longitudinal strain εl is constant at all points and is not a function of the radius ‘______’.

<p>x</p> Signup and view all the answers

The maximum hoop stress allowed is ______ MPa.

<p>35</p> Signup and view all the answers

The pressure varies from p (at r2) to ______ (at r1).

<p>zero</p> Signup and view all the answers

The thickness of the shell determined was ______ mm.

<p>20.96</p> Signup and view all the answers

The designed internal fluid pressure of the first cylinder is ______ MPa.

<p>45</p> Signup and view all the answers

After re-boring, the new inner radius must not exceed the previous hoop stress by more than ______%.

<p>5</p> Signup and view all the answers

To calculate hoop stress, the external radius is denoted as ______.

<p>R1</p> Signup and view all the answers

Study Notes

Longitudinal Stress in Thick Cylinders

  • Longitudinal stress remains constant throughout a thick cylinder despite radius variations.
  • Plane sections normal to the cylinder's axis retain their flatness under internal fluid pressure.
  • Longitudinal strain (εl) is uniform across all points, independent of the radius 'x'.

Lame’s Assumptions and Constants

  • Material constants E (Young’s modulus) and μ (Poisson's ratio) are critical for stress calculations.
  • According to Lame's assumptions, longitudinal stress (σl) is also constant within the cylinder.
  • The algebraic sum of hoop stress and radial stress equals 2A, where A is Lame’s constant.

Pressure Variation and Stress Analysis

  • Internal fluid pressure (p) applies at the cylinder's inner radius (r2), while the outer surface is under atmospheric pressure (datum).
  • Radial stress (px) changes from internal pressure p at r2 to zero at r1.
  • An elemental ring can be evaluated for bursting and resisting forces to analyze stability.

Lame's Equations

  • Lame's equations address radial pressure and hoop stress for thick cylinders subjected to internal or external fluid pressures.
  • Radial pressures at specific boundaries lead to varying hoop stresses.
  • Conditions dictate boundary stresses at both inner and outer surfaces based on fluid pressure effects.

Stress Types in Thick Cylinders

  • Maximum hoop stress occurs at the inner surface, while minimum hoop stress occurs at the outer surface.
  • Radial stresses also vary, with maximum radial stress at the inner surface and minimum at the outer surface.
  • Longitudinal stress depends on internal/external fluid pressures and their effects on the structure.

Strain Analysis

  • Strains in the cylinder include hoop strain, longitudinal strain, and radial strain.
  • The volumetric strain considers the storage capacity of the thick cylinder and changes due to internal pressures.

Lame’s Constants and Stress Conditions

  • Lame’s constants A and B indicate whether the cylinder is under internal or external pressures, signifying tensile or compressive stresses.
  • The stress state varies significantly depending on the enclosures (open or closed ends) of the cylinder and the pressures applied.

Practical Examples

  • Given a thick cylinder of specific diameters and internal pressures, stresses can be calculated using Lame’s equations.
  • Change in wall thickness, hoop strain, and impacts of pressures define the mechanical behavior of the cylinder.

Problem Solving and Analyses

  • Calculating maximum hoop stress and radial stress using boundary conditions provides insights into cylinder performance.
  • Changes in dimensions such as inner and outer diameters directly affect the resistance to pressures and overall stability.
  • Evaluation of re-boring impacts on maximum hoop stress limits emphasizes the importance of design considerations in engineering applications.

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Description

Test your understanding of the properties of thick cylinders under longitudinal stress. This quiz covers important concepts such as the independence of longitudinal strain from the radial position and the behavior of plane sections under internal pressure. Perfect for engineering students looking to reinforce their knowledge.

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