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Ma C.-W.,China Aerospace Science and Technology Corporation | Lu G.-F.,AVIC Special Vehicle Research Institute | Li G.-L.,China Aerospace Science and Technology Corporation
Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics | Year: 2013

Based on cohesive zone finite element, the elements deformations in integrated composite structures are accumulated in these interface layers, subsequently the interface delamination growth is characterized by displacement jump δ. According to this view, the relationship between damage-life and strain energy release rate-life is established, and the displacement jumps are divided into three conditions under quasi-static loads. Based on the four hypotheses, it is proposed that the fatigue total lives of the delamination consists mainly of matrix crack initiation life, the lives for delamination onset from this matrix crack and the lives for stable delamination growth to a finite acceptable delamination size. The computational method for interface damage cumulative and prediction programs for delamination fatigue total lives are proposed. Finally, delamination fatigue total lives are predicted under constant-amplitude and variable-amplitude fatigue loadings through two examples, the computational values are consistent well with experimental data, which confirms the validity of this method in this paper.

Sun Y.,Harbin Engineering University | Su Y.,Harbin Engineering University | Wang X.,AVIC Special Vehicle Research Institute | Hu H.,Harbin Engineering University
Engineering Applications of Computational Fluid Mechanics | Year: 2016

This paper presents the simulated and experimental results of propeller-rudder systems with propeller boss cap fins (PBCFs) and analyzes the hydrodynamic performance of PBCFs in propellerrudder systems. The purpose is to study the impact of PBCFs on the hydrodynamic performance of rudders. Hydrodynamic experiments were carried out on propeller-rudder systems with PBCFs in a cavitation tunnel. The experimental energy-saving effect of the PBCF without a rudder was 1.47% at the design advance coefficient J = 0.8. The numerical simulation was based on the Navier-Stokes equations solved with a sliding mesh and the SST (Shear Stress Transfer) k-ω turbulence model. After the grid independence analysis, the flow fields of an open-water propeller with and without a PBCF were compared, then the efficiencies of the propulsion systems including different rudders and the thrust coefficient Kr of rudders were analyzed. The results indicate that the installation of a PBCF increases the resistance of the rudder, which results in a reduction in the energy-saving effect of the PBCF. At the design advance coefficient, the energy-saving effect of the PBCF with an ordinary rudder and a twisted rudder decreases from 1.47% to 1.08% and 1.16%, respectively; thus, it is important to factor in the rudder of a propulsion system when evaluating the energy-saving effects of PBCFs . © 2015 The Author(s). Published by Taylor & Francis.

Li Y.,Huazhong University of Science and Technology | Li Y.,AVIC Special Vehicle Research Institute | Wu S.,Huazhong University of Science and Technology | Su W.,AVIC Special Vehicle Research Institute | And 2 more authors.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2012

In a recent decade, the titling gravity process is a very popular process for casting manufacturers, which is beneficial for the discharge of slag and gas from bottom to top during filling and sequential solidification of castings due to integrating the advantages of the bottom gating system and the top gating system. The double-barreled tank possesses a large and thin-wall structure with air-tightness requirement. Some casting defects, such as misrun and cold shut easily, occurred in the castings due to be difficult to form. Some defects in the double-barreled tank as slag and gas hole and the qualification rates of castings after machining and air-tightness testing are greatly improved by the titling gravity casting with optimized gating system and processing parameters.

Li Y.-X.,Huazhong University of Science and Technology | Li Y.-X.,AVIC Special Vehicle Research Institute | Wu S.-S.,Huazhong University of Science and Technology | Su W.-Q.,AVIC Special Vehicle Research Institute | And 2 more authors.
Zhuzao/Foundry | Year: 2011

The defects of HOWO tank made with top gating system and inclined-pouring process were analyzed, and some improving measurements were put forward. The trial production result shows that the step gating system is more suitable for batch production. With this process the defects such as slag, gas-hole and porosity can be effectively eliminated, and qualified products can be produced. The improved technology scheme has been successfully used in production of other tens types of thin wall tanks.

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