Evaluation of Fatigue Crack Propagation of Gears Considering Uncertainties in Loading and Material Properties

Abstract

Failure prediction of wind turbine gearboxes (WTGs) is especially important since the maintenance of these components is not only costly but also causes the longest downtime. One of the most common causes of the premature fault of WTGs is attributed to the fatigue fracture of gear teeth due to fluctuating and cyclic torque, resulting from stochastic wind loading, transmitted to the gearbox. Moreover, the fluctuation of the torque, as well as the inherent uncertainties of the material properties, results in uncertain life prediction for WTGs. It is therefore essential to quantify these uncertainties in the life estimation of gears. In this paper, a framework, constituted by a dynamic model of a one-stage gearbox, a finite element method, and a degradation model for the estimation of fatigue crack propagation in gear, is presented. Torque time history data of a wind turbine rotor was scaled and used to simulate the stochastic characteristic of the loading and uncertainties in the material constants of the degradation model were also quantified. It was demonstrated that uncertainty quantification of load and material constants provides a reasonable estimation of the distribution of the crack length in the gear tooth at any time step.

Digital Twin-Driven Remaining Useful Life Prediction for Gear Performance Degradation: A Review

“…The crack expansion method can be referred to Refs. [72][73][74], and the crack initiation method can be referred to Refs. [75][76][77].…”

Development of a Statistical Reliability-Based Model for the Estimation and Optimization of a Spur Gear System

“…They are made to operate under higher and variable load and speeds condition and sometimes affected by vibration. These operating conditions, however, have resulted in an increase in the number of failures that is observed in today's modern gear systems applied in so many industries (Endeshaw et al, 2017). The fatigue strength and wear conditions of the gears, which are one of the most important criteria considered while designing, can be regarded as a key contributory factor to the high failure rate recorded in the system, where this is due to the billions of load cycles each of the gear tooth need to experience during operation.…”

“…Alemayehu and Ekwaro-Osire (2014) performed a probabilistic multi-body dynamic analysis in a high-speed-parallel-helical-stage of a wind turbine gearbox by considering and measuring the uncertainties in the following gear parameters: generator-side, torque-loading, input-shaft speed, and the different assembly and design parameters which causes failure due to variations. Endeshaw et al (2017) presented a framework that consists of a dynamic model of a one-stage gearbox, a finite element method, as well as a degradation model for the estimation of fatigue crack propagation in the gear system. A torque time historical data for a wind turbine rotor are used to simulate the stochastic characteristic of the loading and uncertainties in the material constants of the degradation model.…”

Bi-level Hybrid Uncertainty Quantification in Fatigue Analysis: S-N Curve Approach

“…In this particular, three main approaches coexist: (a) probabilistic; (b) Bayesian inference; (c) probability bounds analysis (PBA). A considerable amount of research works is based on the so-called probabilistic methods, for example, [7][8][9][10][11][12][13][14][15][16]. The probabilistic approach is an adequate representation of an UIQ when there is sufficient random data to be representative of the distribution.…”