Change of volume in pure torsion

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In pure torsion, the change of volume is zero because the normal stresses are absent, which means there are no volumetric changes. Pure torsion occurs when external forces act perpendicular to the bar axis, generating only torsional moments along the axis. Evaluating the three principal stresses in this scenario shows that they sum to zero, confirming the absence of volume change. The presence of normal stress at a 45-degree plane does not affect the overall condition of pure torsion. Thus, the fundamental definition of pure torsion supports that there is no change in volume.
joltu
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why change of volume in pure torsion is zero?
if you consider stress in plane with degree of 45 there is normal stress
normal stress can lead to change of volume
 
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define "pure torsion"...
 
Pure torsion appears when exterior forces acting perpendicular to the bar axis
produce only moments of torsion acting along the bar axis
 
i.e. pure torsion is defined to be the case where the normal stresses are zero.
 
joltu said:
why change of volume in pure torsion is zero?
if you consider stress in plane with degree of 45 there is normal stress
normal stress can lead to change of volume
See what you get if you evaluate the three principal stresses. Do they sum to zero?
 
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