shaft strength 1

[kuds]

Hi all,
I have a hollow shaft of 2" outside dia to 1.25" inside dia, about 1.5 ft in length.I also have a notch going around the outside periphery of the shaft. The shaft also has 2 holes drilled tranversely through the shaft
The shaft will be rotating and will have torsion and probably bending load.
I calculated that the strength of this hollow shaft will reduce by about 15% compared to a solid 2" shaft.How can I further calculate the reduction in strength taking into consideration the drilled tranverse holes & the notch.Thanks in advance.

john

 

[CESSNA1]

kuds: You will the stress concentration factor for the notch. Soome limited data is in handbooks such as Mark's Handbook. I suggest that you oreder the book like "Peterson's Stress Concentration Factors" by Walter D. Pilkey, Joel E. Peterson, and Karin Clark; for a complete list. It lists for $175 plus shipping and tax at Barnes and Noble. There are other books also.

Regards
Dave

 

[unclesyd]

Here is an excellent site posted by metengr that will give you all the factors you need.

http://www.fatiguecalculator.com/constamp/index.htm

 

[Cockroach]

The best way would be FEA, the transverse holes would be difficult as a hand calculation.

You can assume such factors contribute minor stress concentrations to the system, since drilled material removes only small amounts of mass. Then you can simply model the hollow shaft WITH the notch, the notch would add to stress in a major way.

Again, probably FEA would be the best on complicated geometry.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[zcp]

And don't get too starry eyed with the FEA. Pay attention to your loading and boundary conditions. You may want to break it into one run for torsion and one for bending to get your stress concentration factors, then combine with a fatigue analysis by hand. I would think the transverse holes would be a big factor depending on size and location.

ZCP

http://www.phoenix-engineer.com

 

[BARTHURS]

I agree with zcp.

Brandon B. Arthurs, P.E.

 

[kuds]

thanks for all the help.