Reliability prediction of helicopter transmission systems using stress-strength interference with underlying damage accumulation

This paper describes research into the development of reliability predictio n models for rotor transmission systems in which component failure is cause d by underlying aging processes such as fatigue, wear or corrosion. Reliabi lity prediction is based on the stress-strength interference methodology, w ith stress related to surface damage and strength to the limit of allowable damage. The paper describes how damage accumulation and system failure log ic is incorporated within the stress and strength functions. For fatigue-do minated processes, damage grows with number of cycles in response to applie d load and environmental conditions. The concept of 'operating state' is us ed to model statistical damage accumulation. Operating states describe load and lubrication conditions and associated statistical damage accumulation rate parameters. Growth rate variance is related to operating state transit ions and can be modelled using stochastic techniques. Fatigue strength is o btained from S-N data. Formulated in this way, reliability can be predicted from design and operational parameters rather than historical failure data . Copyright (C) 1999 John Wiley & Sons, Ltd.