Design, Analysis And Testing Considerations Of Fatigue-Critical Rotorcraft Components

Three different analysis methods namely, the classical safe-life method, the damage-tolerance method and the integrated method are discussed in terms of their typical design requirements. design analysis and the resulting reliability produced. The comparison is illustrated through a simple example problem of a plate with a hole subjected to random oscillatory load. The integrated method is shown as a method of analysis possessing features that are suitable for substantiating high reliability levels in fatigue-critical rotorcraft components. The importance of employing a local strain method in anaiyzing ground-air-ground (GAG) cycles is discussed and an example problem is solved. A rationale for including an appropriate number of GAG cycles in elevated load fatigue testing is discussed.