Plastic deformation measurement

[shingouz]

Hello,
I made some tests on bolted double shear joint (just 1 bolt assembling the 3 plates) and suspect that there is some plastic deformation into the bolt due to bending (like you can see in the attached image). I was wondering how can I measure this plastic deformation ? At first I thought an optical microscope would be sufficient but is there any other method to do this (I think that occuring plastic deformation is order of 0.003 inch and the diameter of my bolt is 1/4 inch)
Thanks a lot for help

 

[rb1957]

it certainly looks like it !

a CMM would do it.

how are you getting the bolt out of the hole ?

a dial gauge on the middle plate; datum would be when the middle plate starts to carry load (i'm asusming that initially there is a small gap between the plates and the bolt). Load, and unload, the permanent set should be the difference between the dataum and the unloaded readings.

 

[mfgenggear]

shing

Yikes doesn't good.

if it is possible to remove the bolt without further damage.
as rb1957 states a CMM would be the easiest.

if no CMM is available then a manual inspect of the bolts before after the test.

Good Luck
Mfgenggear

 

[shingouz]

Thank you guys, yeah it is better to use CMM for this purpose and i'll use a roundess tester.