burst rpm

[dyno100]

hi, can anyone give me an idea on the burst rpm of a 24" diameter x 1.750 thick low carbon steel wheel? thanks.

 

[ishvaaag]

http://www.excelcalcs.com/repository/machines/miscellaneous/stress-in-a-rotating-disk.xls/

Hope this helps.

 

[nento]

Hi ishvaaag.

Bursting disk is due to centrifugal force due to rotation. The force will tear away the rotating material if it exceeds the force that "hold" the material in place. This force depends on the peripherial speed and the density, whatever the thickness is.

The equation I usually use to make centrifugal pump is

St.u = rho*v^2/g.

St.u = Ultimate stress in kg/cm2
rho = density in kg/cm3
v= peripherial speed in cm/sec.
g - gravity factor 981 cm/sec2

Safety factor has not been considered

Let the steel density rho=0.0785 kg/cm3
Ultimate stress = 4100 kg/cm2 ( I guess at this range)
Gravity = 981cm/sec2

so v = sqrt(4100*981/.0785)= 7158 cm/sec= 2242 RPM. for 60.96 cm disk.

Applying allowable stress of 1400 kg/cm2 you can turn the disk safely at about a half. Provided no other external load from any sources that may influence this force.

Regards

 

[ishvaaag]

Thanks, dyno.

 

[ishvaaag]

... er, nento.