Shi D.,Beihang University |
Dong C.,Beihang University |
Yang X.,Beihang University |
Sun Y.,Beihang University |
And 2 more authors.
Materials and Design | Year: 2013
Experiments are carried out at elevated temperature to investigate the effect of brazing itself and post-brazing heat treatment on the lifetime of directionally solidified (DS) superalloy. Meanwhile, a new lifetime prediction methodology based on continuum damage mechanics (CDM) is proposed to predict the lifetime of DS superalloy and its brazed joints. After creep and fatigue testing, the fractured specimens are observed by means of Optical Microscope (OM) and Scanning Electron Microscope (SEM) with the Energy Dispersive X-ray Spectrometer (EDXS) to understand their failure mechanisms. The results showed that: (1) under the same test condition, all the brazed joints exhibited a lower creep and fatigue lifetime compared with a typical DS superalloy; (2) the creep and fatigue lifetime of heat treated brazed joint was longer than that of non heat treated one; (3) the developed CDM method can be used to predict the lifetime of all the specimens; (4) all the brazed joints fractured in the brazing seam; and (5) there were many distinctive differences between the failure mechanics of DS superalloy and its brazed joints. © 2012 Elsevier Ltd.
Wang J.,China Institute of Water Resources and Hydropower Research |
Jia B.-H.,Beijing Institute of Technology |
Li W.,China Aviation Engine Establishment |
Wang R.-L.,CAS Center for Space Science and Applied Research
Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology | Year: 2013
To research the mechanical behavior of concret under dynamic loadings, the mechanical behavior and the failure modes of concrete under quasi-static or dynamic compressive loadings were investigated by a two-dimensional finite element model which was established by a self-developed program. Random distribution of coarse aggregate in concrete was obtained by using this program. In the developed program, concrete was regarded as a two-phase composite material of cement mortar and coarse aggregate. The effectiveness of established finite element model was verified by comparing of numerical predictions with experimental results. Then, the effects of coarse aggregate size distribution and coarse aggregate volume fraction on the mechanical behavior and failure modes of concrete under dynamic loadings were analyzed. The results of this research could provide a basis for the structural optimization and design of concrete.
Sun C.,China Aviation Industry General Aircraft Co. |
Ren Y.,Hunan University |
Chen F.,China Aviation Engine Establishment |
Zou D.,China Aviation Industry General Aircraft Co.
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2015
To predicate the life of composite structures, the prediction methods of composites fatigue life were reviewed. The residual stiffness model was established and the concept of residual strain was proposed. Using finite element analysis tool Abaqus, a user defined subroutine UMAT was embedded into the general FEA package to realize the life prediction of composite structures. Fatigue properties of the composite material TS800 were studied and some experimental data for engineering applications was obtained. Finally, the life prediction of the composite structures was conducted, which agrees well with the test data. © 2015, Harbin Institute of Technology. All right reserved.
Huang Y.,Beihang University |
Zhao R.,Beihang University |
Li W.,China Aviation Engine Establishment
Journal of Geophysical Research: Atmospheres | Year: 2013
A particle superposition model combined with a Monte Carlo ray tracing method, which is used to study the radiative characteristics of large nonspherical particles, is proposed. The goal of the model is to provide a new approach that not only allows the modeling of large irregular particles of arbitrary shape but also possesses a clear and systematic basic structure that is easy to program. A detailed flow chart and algorithm description are provided in the paper. The data characteristics of four types of irregular particles were calculated and analyzed. The comparison showed that this particle superposition model can be used to calculate the radiative properties of large irregular particles with good accuracy, while at the same time remaining general and extendable to many applications, thus providing a new way to study nonspherical particles. Key Points A particle superposition method is proposed Capable to calculate particles of arbitrary shape and inhomogeneous medium Comparisons of data validate the good accuracy of the method ©2013. American Geophysical Union. All Rights Reserved.
Jia Z.-G.,China Aviation Engine Establishment |
Wang R.-Q.,Beihang University |
Hu D.-Y.,Beihang University |
Fan J.,Beihang University |
Shen X.-L.,Beihang University
13th International Conference on Fracture 2013, ICF 2013 | Year: 2013
The multi-field coupled analysis, a higher precision, is an interaction effect among the fluid, the structure strength and the thermal on the turbine design. Considering the coupled effect in the multidisciplinary optimization design (MDO) could further excavate the design potential and improve the optimization precision on the turbine. Thus the paper firstly shows the automatic process of the fluid-solid closely coupled analysis method based on the ALE which would be the foundation of the turbine MDO. The comparison between the analysis result of the couple and the single discipline on the turbine blade proves the transdisciplinary influence each other. Based on kinds of the different precise analysis methods, this paper secondly puts forward the multiple-precision strategy in order to balance the cost and the precision on turbine MDO. This strategy studies the variable complexity method (VCM) which is improved by the two-point scale function and the periodic updating technology and three kinds of precise models including the fluid-solid closely coupled analysis, the single discipline analysis and the approximate equation. The strategy solves the difficulty of disciplinary decoupling and coordination by the collaborative optimization (CO) strategy. Finally, the new strategy could finish the turbine MDO with acceptable performance.
Feng S.,Northwestern Polytechnical University |
Wang Z.,Northwestern Polytechnical University |
Chen W.,Northwestern Polytechnical University |
Qiao S.,China Aviation Engine Establishment |
Xue H.,Northwestern Polytechnical University
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2014
To estimate the useful life of servicing structural material by nondestructive approach, especially to estimate the remaining fatigue life of specimen that have undergone unknown number of cycles of loading, a remaining fatigue life prediction method is proposed in this paper. Using 300M steel specimen to perform fatigue tests with different cyclic load amplitudes, the temperatures of all specimen are monitored by infrared thermography during the whole tests. The data of slopes of initial temperature rise caused by excitation load is recorded to construct the "reference slope surface series" which reflected the relation of the thermal response of specimen and fatigue life, this is the foundation for estimating remaining useful life of high-strength steel. The results show that slope of initial temperature rise caused by excitation load is linearly related to fatigue damage, that is, accumulated numbers of cycles of specimen. The experimental verification suggests that the error of this remaining fatigue life estimation is less than 5%; hence, this relation can be employed as an indicator for estimating remaining fatigue life.
Li W.,China Aviation Engine Establishment |
Huang Y.,Beihang University |
Fu B.,China Aviation Powerplant Research Institute |
Cui Y.,Shanghai Aircraft Design and Research Institute |
Dong S.,Beihang University
Tribology International | Year: 2013
This paper presents a methodology to study the fretting damage behavior by combined finite element-discrete element method based on FFD method and cut boundary displacement method. A discrete element modeling technique is developed. An inter-element contact constitutive model and its microscopic parameters are determined and calibrated to reproduce continuous and discontinuous behaviors of material in DEM. A crack visualization technique is developed to display cracks according to their failure mode and time dependency. The effect of fretting condition on crack initiation and propagation as well as fretting damage is studied. The mechanism of fretting wear is investigated. © 2012 Elsevier Ltd. All rights reserved.
Jia Z.,China Aviation Engine Establishment |
Wang R.,Beihang University |
Hu D.,Beihang University
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2013
This paper is a study on the multidisciplinary design optimization (MDO) involving coupling, because the MDO in the past failed to consider the coupling analysis of high precision. Taking both optimization efficiency and precision into consideration, this paper constructs a turbine blade optimization strategy with coupling based on collaborative optimization (CO). This strategy incorporates the variable complexity method (VCM) which is improved by the two-point scale function and the periodic updating technology and three accuracy classes (high, middle, low) of the analysis models, i. e. the fluid-solid coupled analysis, the single discipline analysis and the response surface approximate equation. The new strategy solves the difficulty of precision and efficiency, and shown to be able to complete the turbine MDO with satisfactory performance.