Answer
The load-deflection characteristic for a multi-turn crest-to-crest wave spring is governed by the formula $P = \frac{E \cdot b \cdot t^3 \cdot n^4 \cdot f}{D_m^3 \cdot N} \cdot K$, where $P$ is the load, $E$ is the Modulus of Elasticity, $b$ is the radial wall, $t$ is the material thickness, $n$ is the number of waves per turn, $f$ is the deflection, $D_m$ is the mean diameter, and $N$ is the number of active turns. The factor $K$ represents a correction for the curvature of the material. It is vital to note that this linear relationship typically applies between 20% and 80% of the available deflection. Beyond this range, the spring rate increases exponentially as the waves begin to flatten and contact the adjacent turns or the housing surface, leading to a condition known as 'bottoming out' or 'solid height' approaching. Engineers must ensure the working height $H_w$ is greater than the solid height $H_s = N \cdot t$ to prevent permanent plastic deformation.
