ANALYTICAL MODELING OF FATIGUE LIFE ON ROD END BEARING SYSTEM

CURRENTLY, AS REPORTED IN PROGRAM SOLICITATION 90.1 BY THE AIR FORCE, THE SPECTRUM OF BEARING AND BEARING LINER MATERIALS USED IN THE AIRCRAFT BEARING SYSTEMS BEHAVE IN AN UNEXPECTED WAY WHEN SUBJECTED TO CYCLIC LOADINGS. TO INVESTIGATE THE PROBLEM AND BETTER PREDICT THE FATIGUE LIFE OF THIS ROD AND BEARING SYSTEM, FUNDAMENTAL ANALYSES OF STRESS DISTRIBUTIONS, STRESS INTENSITY FACTORS, FATIGUE CHARACTERISTICS, AND WEAR AND FRACTURE ARE REQUIRED. AN ANALYTICAL MODEL TO PREDICT THE FATIGUE LIFE OF ROD END BEARING SYSTEM IS PROPOSED FGOR THE PHASE I WORK. SPECIFICALLY, THE STRESS FIELD FOR THE ASSUMED HERTZIAN LOADING AROUND AN ASPERITY IS CALCULATED, ALONG WITH A CORRECTION FACTOR TO ACCOUNT FOR THE THREE-DIMENSIONAL EFFECTS; THE MODE II (SHEARING MODE) STRESS INTENSITY FACTORS ARE THEN CALCULATED FROM TEH OBTAINED STRESS FIELD; THE FATIGUE LIFE IS FINALLY MODELED BASED ON THE CHARACTERISTICS OF CYCLIC LOADING AND FRACTURE GROWTH BY USING THE CALCULATED STRESS INTENSITY FACTORS. FEASIBILITY OF THIS MODEL WILL BE EXAMINED AND DEMONSTRATED FOR VARIOUS TYPES OF INITIAL MICRO-CRACKS, E.G. THE VERTICAL EDGE CRACK, THE INCLINED EDGE CRACK, THE INTERIOR HORIZONTAL CRACK, THE INTERIOR VERTICAL CRACK AND THE INTERIOR INCLINED CRACK.