What impact does the 'Shim End' feature have on the pressure distribution of a Crest-to-Crest wave spring?

Shim ends, also known as flat ends, provide a $360^{\circ}$ contact surface compared to the point contact of plain ends. This feature significantly reduces the localized contact stress on mating components, which is vital when the spring interfaces with soft materials like Aluminum or plastics. Mathematically, the shim end acts as a rigid boundary condition, improving the stability of the stack and ensuring that the load $P$ is distributed uniformly across the circumference. However, the addition of shim ends increases the solid height $H_s = (Z+2)t$, which must be accounted for in the axial space claim.