1. Why use Neuber’s Rule?
An elastic-plastic strain time history is needed to calculate fatigue life, but sometimes only an elastic stress time history is available. For example, when using a linear finite element model and applying forces, the predicted stresses are elastic (Figure 2).
For each time point in an elastic stress time history, Neuber’s Rule calculates the corresponding elastic-plastic strain by keeping the red areas (plastic) and blue areas (elastic only) equivalent as shown in Figure 3.
Neuber’s Rule works as follows: