A flywheel is a heavy disk-like structure used in machinery which acts as a storage device to store energy when energy input exceeds demand and releases energy when energy demand exceeds supply. In steam engines, internal combustion engines, reciprocating compressors, and pumps, energy is produced during one stroke, and the engine is designed to run the entire cycle with the energy produced during that one stroke.
The stress concentration factor is dependent on the geometrical changes of cross-section, such as a hole, notch, or fillet in the component. This can be designed for as it only depends on the geometry and not on load condition. Moreover, the stress concentration factor is a dimensionless factor that is used to quantify how concentrated the stress is in a material.