Bushing Hoops Stress Testing

[suspguy]

Hello

Is anybody familiar with how a press fitted bushing inside a boss (solid outer metal + rubber+ inner metal) is tested for hoops stress

Once a supplier told me that they test it with no rubber inside the bushing , my question is in that case if I wanted to hand calculate the hoops stress for bushing press fitted inside a boss should i consider a solid metal cylinder instead of a bushing or a hollow metal cylinder (with ID = bushing outer metal ID)

I dont if I am clear enough

Thanks for any help

 

[GregLocock]

Why would you be interested? Anyway, use the hollow metal cylinder. Some bushes yield when they are pressed in, I'm not a huge fan, it might save a cent or two up front (no sizing op on the bush) but the prototyping and production ramifications are bad.

Oh, and if the bush outer is of the same order of stiffness as the boss, you have a much more interesting calculation. use FEA!

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[edrush]

This is a bushing with an outer steel ring, an inner steel ring, and rubber in between?

You could hand calculate a deflection for the housing and the outer ring of the bushing, determine the spring rate of each, and then solve for the radial deflection obtained with equal and opposite pressure on each part.

Unless the rubber is trapped (so it can’t expand/deflect), it will not affect your calculation. You will want to make the calculation for hollow cylinders, not a solid cylinder.

ProE Mechanica can handle this and is extremely easy to use. If you have access to Mechanica use a surface-to-surface contact between the outer bushing ring and the housing in the radial direction and then tie the other directions down with constraints.

 

[suspguy]

edrush

Let me see if I understand it correctly

I am trying to use the equations for interference fits in thick cylinders to calculate the hoop stress ( you can find these equations in any machine design book)

In tht case I am assuming a bushing is inserted into a boss , only the outer sleeve of the bushing is inserted in the boss
is that assumption true, if not what should the inner diamtere of the inserted cylinder(bushing) be??

thanks for your help
and I oly want to use hand calcs and not any analysis software

Thanks