Kugel — EMDR — Vorsichtsmaßnahmen und Tipps: Danke Klaus!! https://visionblueenergy.wordpress.com/ Gute Besserung!!!
Accident with ball magnet EMDR motor generator For a rotating Neodynium Magnet sphere, we need to look at the hoop stresses developed due to rotation and compare them with the mechanical stress (Tensile) that the material can withstand up to failure.
The general formula can be applied:
HoopStress = Density x AngularSpeed Squared x Radius Squared
Get Units correctly. Using SI bellow for consistency:
For a typical Neo Magnet and approximate numbers:
Density=7.5g/cm^3 = 7500Kg/m^3
Tensile Strength=75Newton/mm=75000000Pa (N/m^2) or 75×10^6 Pascal
AngularSpeed in Rad/sec
Or 1 rps=6.2832 rad/sec
So as an example:
A sphere of 1 cm radius=0.01m
With density of 7500Kg/m^3
Rotating at 100000 rpm
Develops a HoopStress of 7500 x (100000×0.1047)^2 x 0.01^2 =82215675 Pa or 82×10^6 Pa
Already above the tensile strength. Smaller radius allows for higher speeds.
Eg a 6mm diameter sphere , radius 3mm or 0.003m the stress at 100k rpm is about 7.5 x10^6Pa
Well bellow the limits of failure, all else being in good condition, eg no cracks, inclusions, and so forth.
So be care full out there add a factor of safety 2-5 the higher the better, just to be sure, and an adequate Lexan enclosure.
I hope this helps.
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