FATIGUE SUBSTANTIATION OF TITANIUM LUGS

Document Type : Original Article

Author

Doctor Engineer, Research and Development Sector, Arab British Helicopter Company, Arab Organization for Industrialization, Cairo, Egypt.

Abstract

The purpose of this paper is to calculate the fatigue life of titanium lugs from full scale fatigue substantiation tests using the stress--endurance curve together with a knowledge of the variation of fatigue strength with the mean stress. The tests were carried out using lugs with bushes whereas a helicopter components all have bushed holes. Since, the Goodman diagram for titanium lugs has never been defined, the tests provide sufficient data to draw a Goodman diagram with confidence. A computer program for curve fitting has been designed to determine the different S-N curves from the laboratory fatigue test data. The flight fatigue damage and the safe life for the sections of the titanium lugs as used in helicopter components are calculated on the basis of the flight load levels.