Shaft Key Analysis in FEA

[Arline]

Hi,
I have requirement where i need to validate the key (square of 1.25") strength using FEA. This key is between shaft & coupling.

I did hand calculations for the key but client insists on FEA validation even though it is safe in hand calculations.

Can any one suggest me the simple/idealized method (boundary conditions,etc) of key analysis using in FEA?

I have torque of the shaft & key is made up of steel.

 

[GBor]

There are many way to do this:

1) Model the key and the shaft on which it is located, calculate the pressure that would result based on the shaft torque, apply the pressure to one side of the key.

2) Model both the shaft and coupling, apply contact between the two, apply the torque to the shaft, calculate stresses.

3) Perform an event simulation (much like #2), but perhaps more involved.

4) Etc...

What are your customers expecting?

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[Tmoose]

With a key that big I suspect your hubs are shrink fitted, so the key is out of the picture until a certain amount of torque is applied.

If the load reverses key and shaft damage from "wallowing" is likely.

Once the key is engaged the real situation gets pretty interesting depending on the key clearance and keyway alignment. Unless the bright red zones at the shaft OD are dismissed as local discontinuities, then a variety of possible geometries should be analyzed with gap elements.

There are some online calculators based on the hand calculations.

 

[dakugadu]

Although the modeling details to be incorporated largely depend on the functioning of your physical system and accuracy required;

to compare with a hand calculation (of peak shear stress in the key for failure), a simple 3D model of just the key, with corresponding loads from the shaft and coupling (as point loads on the corresponding nodes; you can calculate the tangential force from torque transmitted) might be sufficient. this assumes that there is always contact between these surfaces and neglects any compressive stresses formed in key during assembly.

This is the simplest and easiest model to validate your hand calculations. you can further add contact elements, model shaft, coupling etc. but they might be necessary only if the surfaces are not always in contact.

 

[MikeHalloran]

It seems strange that anyone would ask for analysis of a key.

Are you sure they weren't concerned with the key_seat_?

I.e., is the shaft hollow, or unusual in some other way?



Mike Halloran
Pembroke Pines, FL, USA

 

[Arline]

Hi,
Thanks a lot for your suggestions. Key problem got solved.
I did 2D simulation considering key,shaft & coupling, torque as input to the shaft. Contact elements are defined at the interface regions.

Again, Thank you all for your support.