Optimum Fillet or Draft

[pyromech]

Folks

We need to apply a static 1000lbs tensile load to a step bar but my concern is necking rupture. Material is Steel 4130. Is there a formula to estimate the optimum fillet radius to use? or whether a draft taper will work better? If not, a FEA software like Creo structure will work as well??

 

[drawoh]

pyromech,

I would have thought the the best fillet radius is the biggest one possible.

--
JHG

 

[Jboggs]

Agreed. Bigger is better.

 

[swertel]

Get a copy of Peterson's Stress Concentration Factors.

https://smile.amazon.com/Petersons-...words=peterson's+stress+concentration+factors

--Scott
www.aerornd.com

 

[MintJulep]

Optimum for what?

Lowest stress? Lowest cost? Lowest weight? Least material removed? Most difficult to machine?

 

[pyromech]

Get a copy of Peterson's Stress Concentration Factors.

Thanks. there might not be a formula for two parts with different cross sections.

 

[racookpe1978]

Only 1000 lbs? What are required minimum dims of the dia (upper) and rect (lower) sections?
What's the cyclical rate of loading?

 

[moon161]

Call the machine shop and ask how they would machine the fillet and what radii are convenient. Round up from any calculation to one of these.