Dynamic loads occur in all disc springs where the load continuously changes between a preloaded deflection s1 and a second deflection s2. To suit different applications, dynamically loaded discs can be divided into two categories.
- Disc springs with practically unlimited life capable of exceeding 2×106 cycles without failure.
- Limited life discs capable of achieving a given life of 104≤N≤2×106 without failure.
Critical Stress Affecting Dynamic Failure
For springs dynamically loaded, the tensile stresses on the lower side of the disc are the controlling factors.
In the transitional region it is necessary to calculate the stress cycle at points II and III. The greater resulting figure is then the limiting value for life calculations.
For springs with reduced thickness it is not possible to use the example to evaluate the limiting stress at points II and III. For such springs the stress cycles at these points must be calculated according to equations (1-5) and (7-1) with the higher resulting figure is used for expected life calculations. Point III would be relevant for most springs