Official Answer
Answer
Eccentric loading occurs when the load $P$ is not applied uniformly over the circumference of the wave spring, often due to a tilted plunger or an off-center housing. This creates a non-uniform stress distribution: $\sigma(\theta) = \frac{P}{A} + \frac{M \cdot y}{I}$, where $M$ is the moment caused by the eccentricity. Some waves will be compressed more than others, leading to localized yielding and a decrease in the overall spring rate. In hydraulic valves, this can cause the spool to stick or leak because the spring force is not balanced. To prevent this, the spring must be guided by either a shaft on the ID or a bore on the OD, ensuring that the spring remains centered and the load is axial.
