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Liu L.-J.,Nanjing University of Aeronautics and Astronautics | Chen G.,Nanjing University of Aeronautics and Astronautics | Li C.-G.,Shenyang Aerospace engine Design Institute | Feng G.-Q.,Shenyang Aerospace engine Design Institute | Wang D.-Y.,Shenyang Aerospace engine Design Institute
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2013

In order to diagnose rubbing faults and improve design, it is very important to acquire the radial rubbing location of an aero-engine rotor-stator. Based on the casing vibration acceleration signals of an aero-engine rotor experimental rig, a method for the radial rubbing location identification using Laplacian eigenmaps (LE) and sphere support vector machine was investigated here. Firstly, Laplacian eigenmaps were used to extract the rubbing samples' features, their parameters were optimized with grid search method. Then, the characteristics of the samples were input to a sphere support vector machine to identify different locations of rubbing samples. Besides, with the actual rubbing data, the method was verified and compared with the corresponding results using the principal component analysis (PCA). The results showed the practicability and effectiveness of the method.

Luo Z.,Northeastern University China | Zhu Y.P.,Northeastern University China | Zhao X.Y.,University of Sheffield | Wang D.Y.,Shenyang Aerospace Engine Design Institute
Mechanics Based Design of Structures and Machines | Year: 2015

In this study, we investigate the dynamic scaling laws of geometrically distorted models for predicting dynamic characteristics of thin-walled short cylindrical shells. Approximate and accurate analysis methods for obtaining the scaling laws are introduced. Two coefficient functions are established in deriving high-order scaling laws for a narrow range distorted model. Then a modified function is obtained by using numerical analysis, in order to modify the errors of wide range distorted models. The general form of the high-order scaling laws of thin-walled short cylindrical shells is also developed. To be practical, a process of detecting scaling laws by experimental operation is summarized, and the applicability of scaling laws is validated by using experimental data. Although there are some limitations in practice, the scaling laws of the thin-walled short cylindrical shell still have the ability to predict the prototype with good accuracy. © 2015 Taylor & Francis Group, LLC.

Yu M.,Nanjing University of Aeronautics and Astronautics | Chen G.,Nanjing University of Aeronautics and Astronautics | Jiang G.,Shenyang Aerospace engine Design Institute | Li C.,Shenyang Aerospace engine Design Institute | And 2 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2014

A method of aero-engine rubbing positions identification based on casing acceleration signals was proposed. The rotor experimental rig of aero-engine was used to simulate rubbing faults of different radial rubbing positions. The normalized energy features of wavelet partial maximum modulus were used to input into support vector machine by comparison with directly extracted casing accelerate signal mean square features. The results show that the normalized energy features based on the wavelet partial maximum modulus are more effective than direct extracted casing acceleration signal mean square feature in rotor-stator rubbing positions identification.

Wang X.,Aerospace Research Institute of Materials And Processing Technology | Li S.Q.,Aerospace Research Institute of Materials And Processing Technology | Yang Q.,Shenyang Liming Aerospace engine Group Ltd | Teng B.Q.,Shenyang Aerospace engine Design Institute | And 3 more authors.
Materials Science Forum | Year: 2015

Single shot peening (SSP) with cast-iron shot and double shot peening (DSP) with cast-iron shot and ceramic shot were applied to investigate the relationship between surface integrity status and the fatigue property of titanium alloy TC4 on the notched specimens (stress concentration coefficient Kt=1.7). Surface roughness, residual stress profile and fatigue curve of the notched specimens were tested using scanning profilometer, XRD residual stress tester and rotating-bending fatigue testing machine, respectively. The results showed that surface roughness decreased 18.3% from Ra 1.09 μm post SSP to Ra 0.89 μm after DSP. Moreover, the position of the maximum value of residual stress migrated out close to the surface and the value of surface residual stress raised 12.6% to -800MPa from SSP. Additionally, the fatigue limit of the notched specimens pose SSP increased 64.7% to 467MPa from 283 MPa of AM, furthermore, edged up by 8% from 432MPa on unpeened smooth samples. It may be concluded that the double shot peening on titanium alloy has, therefore, eliminated the weakness of fatigue property caused by stress concentration. © (2015) Trans Tech Publications, Switzerland.

Zhang B.,Nanjing University of Aeronautics and Astronautics | Li J.,Shenyang Aerospace Engine Design Institute | Ji H.,Nanjing University of Aeronautics and Astronautics | Shuai H.,Nanjing University of Aeronautics and Astronautics | And 3 more authors.
Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics | Year: 2011

The effect of relative position between impinging hole and effusion hole is numerically investigated on heat transfer characteristics of impinging/effusion double wall. Results show that heat transfer characteristics change much corresponding to the changes of relative positions. When effusion holes are symmetrically placed besides impinging holes, it causes better heat transfer effect. The non-symmetrical position increases the non-symmetrical pumping effect and decreases the heat transfer effect.

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