WillowEng
Mechanical
- Oct 7, 2015
- 2
Hi everyone,
I am currently reviewing a simple hollow shaft "extension" design which is basically a pipe with a flange at each end under torsion.
Calculations for shear and angle of deflection are readily available, but I have been unable to find a reference for calculating the allowable length. Any references to allowable angular deflection are per unit length or based on an 'allowable deflection' limited by the equipment rather than potential failure of the shaft. The rotational speed of the device is slow, so amount of angular deflection is unlikely to be an issue in operating the device (within reason).
I have scoured the references available and the internet. I have reviewed sources re: thin shell cylinders under pure torsion, but the sources are either far too mathematical to digest and based entirely on theory, or aren't designed for slender use and yield poor results. What I am after is a relatively simple conservative approach - surely this has all been done before and there is a simple method.
Simplified example:
- DN80 SCH40 pipe (OD 88.9mm, ID 77.92mm, thickness 5.49mm)
- Torque of 3000 Nm
I can calculate the deflection, and allowable shear, but how do I know how long I can make the shaft before it fails by 'buckling'?
WillowEng
I am currently reviewing a simple hollow shaft "extension" design which is basically a pipe with a flange at each end under torsion.
Calculations for shear and angle of deflection are readily available, but I have been unable to find a reference for calculating the allowable length. Any references to allowable angular deflection are per unit length or based on an 'allowable deflection' limited by the equipment rather than potential failure of the shaft. The rotational speed of the device is slow, so amount of angular deflection is unlikely to be an issue in operating the device (within reason).
I have scoured the references available and the internet. I have reviewed sources re: thin shell cylinders under pure torsion, but the sources are either far too mathematical to digest and based entirely on theory, or aren't designed for slender use and yield poor results. What I am after is a relatively simple conservative approach - surely this has all been done before and there is a simple method.
Simplified example:
- DN80 SCH40 pipe (OD 88.9mm, ID 77.92mm, thickness 5.49mm)
- Torque of 3000 Nm
I can calculate the deflection, and allowable shear, but how do I know how long I can make the shaft before it fails by 'buckling'?
WillowEng