Application of Multiaxial Fatigue Analysis Methodologies for the Improvement of the Life Prediction of Landing Gear Fuse Pins

Fuse pins are used in landing gear to attach the landing gear to the airframe and are designed to allow for a controlled separation of the landing gear from the airframe in the event of a crash. Traditional uniaxial fatigue analysis methods have been found to either significantly under-predict or over-predict the fatigue life of the fuse pins. To improve the life prediction of these pins, multiaxial fatigue analysis methods were selected and implemented into a custom fatigue analysis program. The analysis procedure includes the constitutive modeling of the elastic-plastic material, notch correction methods, cycle counting methods and fatigue damage criteria. The results of predictions made using the multiaxial fatigue methods for three fuse pin designs were compared to fatigue test data. It was found that the performance of the constitutive model and the choice of fatigue damage criterion had the most effect on the final predicted fatigue life.