“FATIGUE LIFE ESTIMATION OF LANDING GEARS OF FIGHTER AIRCRAFT USING FINITE ELEMENT ANALYSIS”

Abstract

The Total Technical Life (TTL) of fighter aircraft “Article 29L” is 1800 flying hrs. However the TTL of Main Landing Gear (M LG) and Nose Landing Gear (NLG) is only 2000 landing. Considering averag e sortie duration of 45 minutes, the life of LGs should have been ideally 2 400 landings. So there is need to increase the life of LGs. In older days the stress analysis and life extensio n study was carried out considering the experimental stress analysis ap proach and testing, which is time consuming and require huge testing setup. I n order to bridge this gap and to reduce the effort, it is proposed to estimat e the life of the under carriage by Integrated Approach of Finite Element ( FE) Analysis. The determination of the fatigue life of an enginee ring structure is based on two precepts. These are knowledge of the s tructure itself and knowledge of how that structure is loaded. The info rmation required for fully understanding these two singularly complicated item s is significant hence utmost care is taken to estimation of life of LGs. In this work Finite Element (FE) Analysis 3-D geome tric modeling developed using CATIA software. The assembly model was imported in PATRAN software and 3-D mesh was generated using HY PERMESH. Connectivity between the components is provided usi ng the surface to surface contact element. Contact elements are capable of tr ansferring the displacement as per contact status and stiffness of contacting body. The FE model was solved using NASTRAN software for stress and displacement, as per fatigue test load data available. Further fatig ue analysis has been carried out using MSC Fatigue software for fatigue life est imation. alidate FE stress analysis, results were compa red with classical calculations and Rejuvenation zones of MLG. Thus de termine cumulative fatigue damage hot spots can be rejuvenated locally and more no of landing (life of LGs) can be extended accordingly and avoid the experimental stress analysis approach and testing for life extension.