Adaptive Estimation of FCG Using Nonlinear State-Space Models

Abstract

In this paper, an efficient adaptive nonlinear algorithm for estimation and identification, the so-called adaptive Lainiotis filter (ALF), is applied to the problem of fatigue crack growth (FCG) estimation, identification, and prediction of the final crack (failure). A suitable nonlinear state-space FCG model is introduced for both ALF and extended Kalman filter (EKF). Both algorithms are tested in order to compare their efficiency. Through extensive analysis and simulation, it is demonstrated that the ALF has superior performance both in FCG estimation, as well as in predicting the remaining lifetime to failure. Furthermore, it is shown that the ALF is faster and easier to implement in a parallel/distributed processing mode, and much more robust than the classic EKF.

Key Words:

• Adaptive algorithms
• ALF
• EKF
• Fatigue crack growth
• Failure prediction
• Nonlinear FCG models
• Nonlinear prediction
• Stochastic models

Mathematics Subject Classification:

• Primary 93E10
• Secondary 60G35