Stress Concentrations on Shafts
Any abrupt change in parts can capture internal stresses and cause stress concentrations. Examples of these changes are the following:
The stress concentrations are localized and in some occasions can cause microcracks which then can propagate and form bigger cracks with eventual machine breakdown.
A stress concentration factor is defined by the following
Lets take for example the following shaft:
This shaft is expected to have stress concentration on the vicinity of the key seat formation, shoulder, notches, etc.
A 3D FEA analysis can show the problematic areas. Typical types of these analyses include the following loads
- interference fitted parts
- Dynamic loads
Figure below shows results of such simulation with stress concentration on the vicinity of the key
The response of the shaft on the loads applied onto it is a very complicated mechanism and FEA tools are strongly recommended to drive the design process, especially for keyed shaft connections.