Official Answer
Answer
Load loss at room temperature is typically indicative of 'Taking a Set,' which occurs when the operating stress exceeds the material's proportional limit. This is often caused by a design error where the spring is compressed too close to its solid height. The maximum stress occurs at the inner fibers of the wave crests. If $\sigma_{max} > σ_{yield}$, plastic deformation occurs. Another cause is 'Relaxation' due to residual stresses from the coiling process if the spring was not properly stress-relieved. In rare cases, load loss can be attributed to 'Dynamic Set' in high-frequency applications where the spring is subjected to millions of cycles, causing microscopic grain realignment and a slight reduction in free height.
