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Lu F.,Nanjing University of Aeronautics and Astronautics | Lu F.,Institute of the Motor Industry | Chen Y.,Nanjing University of Aeronautics and Astronautics | Chen Y.,Liyang Aero Engine Corporation | And 4 more authors.
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering | Year: 2014

Aircraft engine sensor fault diagnosis is closely related technology that assists operators in managing the health of gas turbine engine assets. As all gas turbine engines will exhibit performance changes due to usage, the on-board engine model built up initially will no longer track the engine over the course of the engine's life, and then the model-based method for sensor fault diagnosis tends to be failure. This necessitates the study of the sensor fault diagnosis techniques due to usage over its operating life. Based on our recent results, an integrated approach based on nonlinear on-board model is developed for the gas turbine engine sensor fault diagnostics in this paper. The architecture is mainly composed of dual nonlinear engine models; one is a nonlinear real-time adaptive performance model and the other a nonlinear onboard baseline model. The extended Kalman filter estimator in the nonlinear real-time adaptive performance model is used to obtain the real-time estimates of component performance, and the nonlinear on-board baseline model with performance periodically update to provide the nominal reference in flight. The novel update strategy to sensor fault threshold based on the model errors and noise level is also presented. Important results are obtained on step fault and pulse fault behavior of the engine sensor. The proposed approach is easy to design and tune with long-term engine health degradation. Finally, experiment studies are provided to validate the benefit of the engine sensor fault diagnostics. © IMechE 2013.

Zhao R.,Xiangtan University | Liu Y.,Xiangtan University | Jiang Y.,PLA Air Force Aviation University | Li Q.,Xiangtan University | And 2 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2015

Probabilistic life prediction of nickel-base superalloy requires the modelling multiple complex random phenomena. The fatigue crack growth rates at various stress ratios are probabilistically predicted using the Paris formula and the modified Paris formula with threshold value ΔKth for fatigue crack growth test data of GH4133B superalloy used in turbine disk of aero-engine at room temperature. The theoretic fatigue crack growth lives Nfp at various survival probabilities P predicted by integral based on the Paris formula and the modified Paris formula are calculated and compared with the test ones Nft. It is shown that Nfp obtained by integral based on the modified Paris formula is well fitted with Nft at P=50%, while both Nfp obtained by integral based on the Paris formula and that obtained by integral based on the modified Paris formula are all well fitted with Nft at P=90%, and Nfp obtained by integral based on the modified Paris formula possesses a high reliability at P=99%. A 3D Nf-Fp,m-Fp,a fatigue life surface are plotted based on the nonlinear regression analysis of fatigue life test data, and a parameter γ is introduced to characterize the effect of mean load Fp,m and load amplitude Fp,a on fatigue life Nf. It is suggested that the effect of Fp,m on Nf is larger than that of Fp,a on Nf. © 2015 Journal of Mechanical Engineering.

Zhao R.,Xiangtan University | Li H.,Xiangtan University | Jiang Y.,PLA Air Force Aviation University | Tan D.,Xiangtan University | And 2 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2013

Fatigue crack initiation and short crack propagation is the key and foundation of damage tolerance design of aero-engine components. The researches on fatigue crack initiation and short crack propagation under different notch radii and stress ratios for GH4133B superalloy used in turbine disk of aero-engine are carried out at ambient temperature. It is shown that a control parameter ΔKI/(rρ)0.5 can be used to characterize the fatigue crack initiation life, and the effect of notch radius on fatigue crack initiation life increases with increasing control parameter, while the fatigue crack initiation life firstly increases and then decreases with increasing stress ratio. An effective stress intensity factor range ΔKeff, can be adopted to describe the deceleration and acceleration of crack growth rate during the short crack propagation. The fatigue fracture surface morphologies are investigated using scanning electron microscopy. It is shown that there is a cleavage step between two adjacent radial stripes, and a series of early fatigue striations exist on the cleavage step, which reveals the microscopic mechanism of short crack propagation from the point of view of fracture surface morphology that the fatigue crack growth rate is intially higher, and then gradually decreases with the propagation of short crack. © 2013 Journal of Mechanical Engineering.

Kong Y.,Donghua University | Chang P.,Donghua University | Li Q.,Donghua University | Xie L.,Liyang Aero Engine Corporation | Zhu S.,Donghua University
Journal of Alloys and Compounds | Year: 2015

The hot compression tests for the nickel-based C276 superalloy were carried out on a Gleeble-1500D simulator in the temperature range of 950-1250 °C with the strain rate range of 0.01-10.0 s-1. The high-temperature deformation behaviors of C276 superalloy were analyzed based on the true stress-true strain curves. The results show that during the hot deformation process of C276 superalloy, under the same temperature, the flow stress rises with the increasing of strain rate. At the same strain rate, the flow stress decreases with the increasing of the temperature. As the strain rate is less than 1.0 s-1, there exist peak stress and steady flow stress, and only peak stress appears at 10.0 s-1. The processing maps of C276 superalloy in different strains were constructed according to DMM model. A small area where the power dissipation efficiency is higher than that in others areas exists in the maps. In this area the deformation temperature and strain rate is 1050-1150 °C, 0.01-0.1 s-1, and the fully dynamic recrystallization has been completed. There exists a small area of rheological instability in the processing map where the temperature is low, while the strain rate is high, and the dynamic recrystallization grains are distributed along the adiabatic shearing zone. According to the microstructure evolution and the processing maps of the C276 superalloy, its suitable processing condition can be summed up as that the temperature range is between 1050 °C and 1150 °C, and the strain rate range is between 0.01 s-1 and 0.1 s-1. © 2014 Elsevier B.V. All rights reserved.

Meng X.B.,CAS Shenyang Institute of Metal Research | Li J.G.,CAS Shenyang Institute of Metal Research | Chen Z.Q.,The Aerospace Corporation | Wang Y.H.,The Aerospace Corporation | And 7 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

A model of typical turbine blade shape with different platforms was designed to study the nucleation and growth of stray grains in the platforms by both experimental investigation and a ProCAST simulation based on a cellular automaton finite-element model. The results show that at the withdrawal rate of 5 mm/min, no stray grains nucleate in the small dimensional platform. However, the primary grain grows into the inner and outer sections of this platform in different manners due to different thermal conditions in these sections. Furthermore, with the increase of platform dimension, stray grains with random orientations gradually nucleate in the corners of the platforms. It is found that these stray grains tend to nucleate either in the inner corners or at a faster withdrawal rate, which is associated with the corresponding thermal condition. Based on these results, the rule of the critical platform dimension and withdrawal rate without stray grain formation has been proposed. Besides, the simulation results are in accordance with experimental findings. © 2012 The Minerals, Metals & Materials Society and ASM International.

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