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Zhang H.-W.,Zhejiang University | Du M.,Zhejiang University | Wang N.,No. 719 Research Institute of China Shipbuilding Industry Corporation | Zheng Q.,Zhejiang University
Acta Polymerica Sinica | Year: 2013

Amino-terminated polydimethylsiloane (SN2) was synthesized by using hydroxyl-terminated polydimethylsiloxane (PDMS) and aminopropyl siloxane coupling agent (DB-912). And the silicone-polyurethane (Si-PU) block copolymer was synthesized by using SN2 as a chain extender and polyurethane prepolymer. The effects of the SN2 and prepolymer of polyurethane feed ratio on the rheological behavior of the copolymer solution in isopropanol (IPA) and the properties of its film were studied in detail. It was found that the Si-PU block copolymer IPA solution with a concentration of 25 wt% exhibited low apparent viscosity and the characteristics of Newtonian fluid within the measuring shear rate scope. During film casting,the SN2 blocks may migrate toward the surface, which led to a surface contact angle to water over 110°. With the increasing of SN2 block content,the surface contact angles of films to water increased slightly. When the films were soaked in the water for 24 h, the water absorptions were very low, and the water-repellence was pretty good. The copolymer film showed water absorption lower than 1. 5 wt%. With the increasing of SN2 block content, the water absorptions were very low and did not change a lot. However,if the content of SN2 block was too high, the water absorption of films increased obviously owing to the increase of hydrophilic groups (-NH2) which possessed good attraction for water molecules. Source


Xu X.,Huazhong University of Science and Technology | Li H.,No. 719 Research Institute of China Shipbuilding Industry Corporation | Zhang T.,Huazhong University of Science and Technology
Baozha Yu Chongji/Explosion and Shock Waves | Year: 2016

This paper aims to obtain the parameters for the failure model based on the Charpy impact test, which has been widely used to study dynamic fracture properties of metallic materials. Based on the explicit dynamic finite element method in ABAQUS, FEM model of Charpy impact test was conducted. We began by discussing the accuracy of the parameters of JC constitutive model and the grid size of the fracture section of V-notch specimen. Then, based on the orthogonal design method, we designed a set of parameters for JC failure model and obtained using finite element calculation the samples of the parameters and impact energy. Next, we obtained the regression equations containing the parameters and impact energy by regression analysis and finally, by solving these regression equations, we achieved the comparatively accurate parameters for JC failure model for Q370d steel. These parameters will be useful for engineering applications and our method will be a valuable way to obtain parameters for other kinds of materials, especially without necessarily meeting the conditions of performing some tests. © 2016, Explosion and Shock Waves. All right reserved. Source


Zhang G.-L.,Shanghai JiaoTong University | You Y.-X.,Shanghai JiaoTong University | Hu T.-Q.,Shanghai JiaoTong University | Zhao L.-M.,No. 719 Research Institute of China Shipbuilding Industry Corporation | And 3 more authors.
Shuidonglixue Yanjiu yu Jinzhan/Chinese Journal of Hydrodynamics Ser. A | Year: 2012

Three-dimensional distribution of the Lorentz force around a hydrofoil coated with electrodes and permanent magnets is obtained by solving Maxwell equation system. Numerical simulations for flow around such a hydrofoil due to the Lorentz force are performed by using the detached-eddy simulation method where the Lorentz force is added to the momentum equation of flow governing equation system. The effects of the electromagnetic interaction parameter and attack angle on the flow structures around the hydrofoil as well as the lift and drag coefficients are investigated. The results show that the Lorentz force applied on the hydrofoil can effectively improve the flow structures around the hydrofoil and suppress its vortex. Stall can be suppressed or delayed for higher attack angles resulting in an increase of the lift and a decrease for the total drag of the hydrofoil. Therefore, the electromagnetic control is an effective way to realize flow controls of hydrofoils. Source

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