Aircraft Structural Integrity Analysis through Fati gue Crack Propagation

Abstract

The life of an aircraft depends mainly on the specific usage of the aircraft. The manufacturer defines a lifetime for the general usage of the aircraft. But with the specific usage of the aircraft, the aircraft structure may fail prematurely or sometimes may have a life time exceeding the manufacturer specified limit. Retiring of an aircraft impose a great loss for the operator. In countries with limited economical capacity, this is a vast issue. Therefore in this research a method to analyse the structural integrity of aircraft is discussed which will reflect the condition of aircraft structure based on the usage. For this purpose, factors effecting the structural integrity are discussed in this research and fatigue crack propagation is identified as the major cause for structural failure in aircraft. Several models are identified for the purpose of analysing fatigue crack propagation and NASGRO model is selected as the most suitable model for this purpose. The most critical structural components of the aircraft structure is identified and is analysed using this model. A mathematical relationship is developed to predict the flight-cycles to failure of these structures. Then the structural integrity of aircraft is revalidated based on this calculation.