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Optimum Fillet or Draft

Optimum Fillet or Draft

Optimum Fillet or Draft


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??

RE: Optimum Fillet or Draft


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


RE: Optimum Fillet or Draft

Agreed. Bigger is better.

RE: Optimum Fillet or Draft

Optimum for what?

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

RE: Optimum Fillet or Draft


Quote (swertel)

Get a copy of Peterson's Stress Concentration Factors.
Thanks. there might not be a formula for two parts with different cross sections.

RE: Optimum Fillet or Draft

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

RE: Optimum Fillet or Draft

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.

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