AnsweredAssumed Answered

Large Deformation / Reality Check

Question asked by Tony Gatta on Apr 24, 2013
Latest reply on Apr 25, 2013 by Jared Conway

Greets all.

This 'experiment' was purely for kicks and I just wanted to share with the group to see

1. if my assumptions are correct and/or

2. I just got lucky

 

I modeled a stainless steel rule (ie shop ruler, scale, etc).  250mm long x ~30mm wide x 1mm thick & ran a nonlinear

simulation (shell elements) with one end fixed and the other with a prescribed rotation of 180* (3.14 radians).

 

I'm sure most of you have seen this before.  I didn't go to 360 as am somewhat attached to my (still straight) ruler.

 

I duplicated the test as best I could in my garage.. put the rule in a vise and used a force gage to bend it around

180*.  I sort of eye balled things a bit, not very rigorous.. but again, just a curiosity.

 

See image attached.

 

SW Simulation predicted ~60 in-lbs reaction moment.

My measurement = ~ 58 in-lbs

 

So back to my question(s):

1. the simulation shows a purely circular deformed shape.  I assume this is because I'm using shell elements,

have a constant moment through the beam.. and no stress calculated throughout its cross-section.  ie.. only

the reactions would be valid -- true / false?

 

2. the 'real' test shows more of the 'parabolic' bending I'd expect.  I don't think the angle or overshoot of my

force gage position should matter much in that I (think) I would always end up with the same reaction moment.

 

The image may not look like 180 rotation though I'm quite sure I managed as much.  May be lens distortion from

camera.. or I lightened up a bit while trying to shoot with the other hand, but you're seeing max force reading at

~180 degrees.

 

Thoughts?

Attachments

Outcomes