deflection of curved cantilever

[ACtrafficengr]

I don't need an exact solution, just a general idea of the behavior.

Given a thin, gently curved cantilever, would deflection differ if the curve was upwards or downwards?

The context is a field-expedient test for fencing blades. The test involves clamping the tang to a tabletop, and hanging a small weight from the tip. If the tip deflects less than one inch, it is judged too stiff to use.

The question is, many fencing blades develop a curve over time as they are repeatedly flexed. Would testing the blade with the curve up or the curve down affect the deflection enough that we should require that all curved blades be tested the same way?

Never mind for now the question of whether a load applied at a right angle is an adequate surrogate for behavior when loaded axially.

Thanks!

 

[rb1957]

if it is "gently curved" then it probably isn't a "curved beam", and straight beam deflections would be near enough. and so it wouldn't matter much if the fencing blade (foil ?) curved up or down. mind you you could test this if the blade had a noticable curve ... test it curved up and then curved down.

btw, i'd've thought that fencing blades were like pool cues ... the straighter the better ?

 

[ACtrafficengr]

We're using rapier simulators for historical fencing, considerably heavier than an foil. Yes, straighter is better, but these blades are specialty items ($75 to $150 each), so people like to use them as long as they safely can.

Usually, a blade will be curved no more than 2" out of straight over 35-40" of length. Most of the curvature will be in the last foot.

I figured it would be similar to a straight beam (the chem-e in the group didn't think so), but would there be any effects from work hardening or similar?

I was going to suggest testing a number of curved blades to see. I think I will.

 

[rb1957]

maybe there is a small effect in changing E due to work hardening, but i'd've thought that "gently curved" would also imply that this was small. there has clearly been some plastic deformation, hence the beam is curved, but i think the deflection due to a load should be near enough the same as with a truly straight beam; the difference is that your datum (your undeflected shape) is different (but the change due to load should be the same).

my 2c ... but testing is much surer !