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Ma D.,Academy of Armored force Engineering | Wo Ong C.,Hong Kong Polytechnic University
Journal of Materials Research | Year: 2010

In our previous study, we modeled the indentation performed on an elastic-plastic solid with a rigid conical indenter by using finite element analysis, and established arelationship between a nominal hardness/reduced Young's modulus (Hn/Er) andunloadingwork/totalindentation work (WeWt). The elasticity of the indenter was absorbed in E r = 1/[(1 - v2)/E + (1 - Vi2)/E i,where Ei, and vi are the Young's modulus and Poisson's ratio of the indenter, and E and v are those of the indented material.However,recalculation by directly introducing the elasticity of the indenter show that the use ofEr alone cannot accurately reflect the combined elastic effect of the indenterand indented material, but the ratio η = [E/(1 - v2)]/[Ei/(1approximate H n/Ec-We/Wt relationship is almost independent ofselected η values over 0-0.3834, which can be used to give good estimates of η as verified by experimental results. © 2010 Materials Research Society. Source


Li Y.-D.,Academy of Armored force Engineering | Li Y.-D.,Yonsei University | Lee K.Y.,Yonsei University
Engineering Fracture Mechanics | Year: 2010

For the first time, real fundamental solutions are proposed for in-plane magnetoelectroelastic governing equations. Dislocation simulation method is used to derive singular integral equations for collinear unequal crack series under mode I loadings. Special cases of a single crack and two collinear equal cracks are used to validate the proposed solution. The effects of crack space, crack length and magnetic/electric loading are discussed. Real fundamental solutions have an advantage over complex fundamental solutions, because real analyses are more straightforward than complex analyses. Moreover, the model of collinear unequal cracks is more practical than that of collinear equal cracks. © 2010 Elsevier Ltd. Source


Li Y.-D.,Academy of Armored force Engineering | Li Y.-D.,Yonsei University | Lee K.Y.,Yonsei University
Engineering Fracture Mechanics | Year: 2010

Interface fracture of a multiferroic composite is studied by the methods of integral transform and singular integral equation. Parametric studies on the stress intensity factor yield three conclusions. (a) The multiferroic composite is more likely to fracture in electric field than in magnetic field. (b) Under magnetostriction, piezomagnetic stiffening does not affect the interface crack, but the influence of piezoelectric stiffening is notable. Under electrostriction, inverse results are obtained. (c) In magnetic loading cases, the piezomagnetic layer should be softer and the piezoelectric strip stiffer; however, if electric loading is applied instead, opposite conclusion should be expected. © 2010 Elsevier Ltd. All rights reserved. Source


Xu B.-S.,Academy of Armored force Engineering
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2010

Remanufacturing engineering is the senior stage of maintenance engineering and surface engineering, and the important part of advanced manufacturing, and the industrialization for the waste products with repair and reformation. The character, named as "two-oriented society and 567", has been held by remanufacturing engineering. The demand from the rapid economy and society development to remanufacturing in China is very urgent, and the preliminary application of remanufacturing has obtained the obvious effect of energy-saving and discharge-reducing. Around the world, the relatively perfect remanufacturing system has been set up in USA. In the recent 10 years, remanufacturing in China develops quickly, especially in policy, industry and theory of remanufaturing, and now China becomes one of the international remanufacturing centers. The front of remanufacturing could be generalized as "exploring the foundational theory, innovating the key technology, establishing the industrial standard". Source


Ma D.-J.,Academy of Armored force Engineering
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2010

The instrumented indentation tests were analyzed by employing dimensional theorem and finite element method. A combined elastic modulus, Ec, was introduced to accurately reflect the combined elastic effect of an indenter and an indented material. Consequently, an approximate relationship between the ratio of nominal hardness to the combined elastic modulus and the ratio of unloading work to total work in indentation was revealed. Based on the relationship, a new method was then proposed for determining elastic modulus of materials, and its accuracy was analyzed. The effectiveness of the method was examined by several experimental examples. Source

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