## Introduction

Load histories in real applications are often complex and irregular. The total fatigue effect of such loads can be estimated by the Miner-Palmgren rule, see the equation below. Fatigue failure is assumed to occur when the Miner-Palmgren equation is true.

${\displaystyle D=\sum {\frac {n_{i}}{N_{i}}}}$

Where:
${\displaystyle D=}$ a constant, often ranging between 0.33 and 3
${\displaystyle n_{i}=}$ the number of occurrences of a specific load cycle progression, ${\displaystyle i}$
${\displaystyle N_{i}=}$ the fatigue life of a specific load cycle progression, ${\displaystyle i}$

## Shortcomings of Miner's rule

The Miner-Palmgren rule is rather rough and neglects several important qualities of a general load history. Among these properties are the order and shape of the individual cycles.