Propeller wood fatique

[amorrison]

Twenty years ago I read that there was no mechanical stress fatique in wooden propellers.
Present information now says that there is fatique in wood propellers
Could someone comment on this change in the laws of physics.

 

[GraviMan]

Hmmm, interesting. I imagine it is rather like steel, in that there is a fatigue limit for infinite life. It will depend on loading and grain orientation. Check out "Wood design and engineering" forum. I imagine centrifugal loads have been pushed higher too.

Mart

 

[Sparweb]

This may be some mis-interpretation of "Rain-erosion", a problem that has always plagued wooden props, not just those made less than 20 years ago.

Consider a notch in the blade, and what would happen if it was left too long. Wood is fantastically resistant to this kind of fatigue - to my knowledge, most woods don't allow crack propagation unless the load is very close to failure.

Wood is sensitive to bearing stresses, and of course, to moisture.

You could look through ANC-18, which is a detailed document about the design of wooden structures.



Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[clun]

I hope the Wood Handbook (FPL-GTR-113) Chapter-4 from USDA may useful for your query.

You should download it from internet.