Looking for some advice with pin problem 1

[ModulusCT]

Hi, it's been quite a few years since I've done anything like this, so I'm a little lost at the moment.

I'm trying to do 2 things... First, I'm trying to clearly define my problem with a loading diagram. Second, I'm trying to decide exactly what kind of stresses I'm dealing with.

I have a series of 0.020" pins, which are ~0.350" long being assembled into a pin jack which requires ~60 grams of force to engage. Assuming that one or all of the pins are slightly bent, or being engaged slightly off center (and therefore, loaded from one side of the pin), how would I determine exactly how much bending or deflection is occurring in the pin (if any) while that 60 grams of force is being applied?

Any help is appreciated.

Mod

 

[Wrenchbender]

Its been a long time for me too, but I think your diagram would just be a column. End conditions would be: one end fixed (going into the receptacle); other end free with an eccentric load.

For calculating stresses, go to a strength of materials book and use one of the column equations, plugging in the known geometry, modulus and force, being consistent with the units.

 

[ModulusCT]

Thanks Bestwrench... I'll give that a shot. And I happen to have my strenghts text right here next to me.

I was wondering if both ends of the pin would be fixed? At one end, the pin is contained within a metal/glass housing, which is static and at the other end it is being engaged into the connector... It shouldn't move until the engagement force is achieved.

Do you disagree?

Thanks

 

[Wrenchbender]

Oh, in that case, the end which is captured by the metal & glass housing would be fixed. The other end, being shoved into the connector, would be fixed in side-to-side translation, but free in rotation. (wikepedia shows what I mean

http://en.wikipedia.org/wiki/Column.)

Axial force is 60/454 lbs. Moment would be determined by your off-center distance. Hopefully you will be able to find the equations for the critical load and for the deflection curve so you won’t have to set up and solve the ODEs. Also note everything is a function of pin insertion distance (column length) with maximum occurring at L = 0.350.

 

[ModulusCT]

Spot on... Thanks for the help. This is a good place to start.