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1. On a Study Concerning Saint-Venant’s Principle | |||
Jian-zhong Zhao | |||
Mechanics 10 March 2008 | |||
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Abstract:This paper reviewed the series of four works of “proof of Saint-Venant’s Principle” published by Wu etc .The four articles proved neither the discrete Saint-Venant type decay of section-forces of the finite elements in the chain model of discretization of the cylinder nor the discrete Saint-Venant-type decay of section-displacements, posed in their papers. Furthermore, the discrete Saint-Venant type decay of section-forces is not provable. Nevertheless, the proposition of the discrete mixed Saint-Venant type decay of the cylinder was discussed in Wu’s articles by taking the “super” forms of the two single decays mentioned above as a priori assumptions, and so the discussion is of uncertainty, or meaningless, for proof of Saint-Venant’s Principle. | |||
TO cite this article:Jian-zhong Zhao. On a Study Concerning Saint-Venant’s Principle [OL].[10 March 2008] http://en.paper.edu.cn/en_releasepaper/content/19153 |
2. Variational Theory: Variable-independence and Consistency | |||
Jian-zhong Zhao | |||
Mechanics 25 January 2008 | |||
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Abstract:Variational theory of elasticity is surveyed in the context of mathematical logic in the present paper. The problem of variable-independence of variational principles raised by Chien is discussed. We find that Chien’s “High-order Lagrange Multiplier Theory”, which deals with the problem of variable-independence and constraint of variational principles, is inconsistent; Luo’s system, which is involved in the problem of variable-independence, is involved in contradictions; the conventional understanding of independence of variables of variational principles connotes contradiction. In the context of mathematical logic, variational theory must be established as a mathematical system of logic, excluding vagueness and misunderstanding. By consideration of logic, variable-independence is understood as identity of variables and then formalization of variational theory is a solution to the problem of variable-independence. Two consistent systems for elasticity, the Axiomatic System of Variation and the Formal System of Variation, are suggested in this paper. | |||
TO cite this article:Jian-zhong Zhao. Variational Theory: Variable-independence and Consistency[OL].[25 January 2008] http://en.paper.edu.cn/en_releasepaper/content/18375 |
3. Stability Analysis of Gradient Elastic Slender Columns | |||
Kong Shenli ,Zhou Shenjie ,Nie Zhifeng ,Wang Kai | |||
Mechanics 12 October 2007 | |||
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Abstract:The problems of stability of slender columns are solved analytically on the basis of modified couple stress theory. The governing equations of equilibrium and the corresponding boundary conditions are obtained by a combination of the basic equations of modified couple stress theory and variational statement. The governing equations of equilibrium are solved and the buckling load of the slender column is assessed. It is found that the buckling load predicted by the newly established model is size-dependent. The difference between the buckling loads calculated from the newly developed model and classical model is significant when the characteristic sizes such as thickness and diameter are small, but is diminishing with the increase of the characteristic sizes. Comparison of buckling loads and buckling modal shapes for various boundary conditions are presented. | |||
TO cite this article:Kong Shenli ,Zhou Shenjie ,Nie Zhifeng , et al. Stability Analysis of Gradient Elastic Slender Columns[OL].[12 October 2007] http://en.paper.edu.cn/en_releasepaper/content/15645 |
4. On the yield functionals in Lagrangian stress space of elastic-plastic materials with internal constraints | |||
Fu Mingfu,Chen Liangsen | |||
Mechanics 02 January 2007 | |||
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Abstract:In the present paper it is shown that the elastic range in the second Piola-Kirchhoff stress space can be chosen in a hyperplane perpendicular to the direction related to the simple internal constraint if the determinate stress response of the elastic-plastic material with simple internal constraints with the condition (2.30) is correctly chosen, otherwise, it is in general in a hypersurface and the normal flow rule by Il’yushin’s postulate will have an indeterminate part( [8]). The choice of determinate stress response is probable because of its indeterminacy ([1]). Therefore the yield functional should be a function of the second Piola-Kirchhoff stress lying in the hyperplane so that it is more simple and the back stress as the geometric center of the elastic range in general is inside the elastic range. Finally some examples are concerned. | |||
TO cite this article:Fu Mingfu,Chen Liangsen. On the yield functionals in Lagrangian stress space of elastic-plastic materials with internal constraints[OL].[ 2 January 2007] http://en.paper.edu.cn/en_releasepaper/content/10562 |
5. Using Engineering View to Design Better Multi-objective Evolutionary Algorithms | |||
Zheng Bojin ,Li Yuanxiang | |||
Mechanics 30 November 2006 | |||
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Abstract:Multi-Objective Optimization Problems(MOPs) are very difficult to solve by traditional methods, so many Evolutionary Algorithms were designed to deal with them. In this paper, we discussed Multi-objective Evolutionary Algorithms(MOEAs) in engineering view, and proposed a new unified framework. According to the framework, we find some possible key points to the design of MOEAs and these key points are discussed. Then we introduce a new MOEA and test it with some famous benchmark functions. The numerical experiments show that the algorithm can obtain more non-dominant solutions which distribute equably and approximately to the Pareto front in less time than some algorithms such as SPEA2, NSGAII and HPMOEA. | |||
TO cite this article:Zheng Bojin ,Li Yuanxiang . Using Engineering View to Design Better Multi-objective Evolutionary Algorithms[OL].[30 November 2006] http://en.paper.edu.cn/en_releasepaper/content/10088 |
6. Tensile behavior of C/SiC with Z-pins Reinforcement | |||
Liu Wei,Jiao Guiqiong | |||
Mechanics 25 October 2006 | |||
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Abstract:Tensile behavior of ceramic matrix composite (CMC) with Z-pins reinforcement was investigated. A preform consisting of plain-weave fabric and Z-pins through thickness reinforcements was infiltrated by chemical vapor infiltration (CVI) technique. The uniaxial unloading and reloading tensile test was used to investigate the tensile damage behavior. The fracture mechanism of the composite was studied by scanning electron microscopy (SEM). The result shows that the tensile strength of plain-weave ceramic matrix composite is reduced lesser because of damage, fracture and flexural deformation of the in plane fiber during pins insertion. The stress-strain curve of the laminate is nonlinear, and the damage undergoes slowly propagating, rapidly propagating and reaches saturation. The relationship between residual strain and unloading stress is quadratic function, and the relationship between unloading modulus and unloading stress is Boltzmann. The relationship between strain and stress of the laminate of plain-weave ceramic matrix composite is obtained. | |||
TO cite this article:Liu Wei,Jiao Guiqiong. Tensile behavior of C/SiC with Z-pins Reinforcement[OL].[25 October 2006] http://en.paper.edu.cn/en_releasepaper/content/8988 |
7. The Correlation between Fractal Dimension of Fracture Surfaces and Mechanical Properties | |||
Liu Haishun,Yin Chunhao,Miao Xiexing | |||
Mechanics 24 October 2006 | |||
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Abstract:The literature on metal fatigue and fracture based on fractal theory is reviewed, focusing on the fractal character of metal fracture surfaces and the approaches to measure the fractal dimension. The correlations between the fractal dimension of fracture, various fractal models of metal fatigue crack propagation and fracture are analyzed and compared, and the physical signification of fractal dimension are also discussed. It seems there is still further research necessary to improve theoretical method and to reveal the physical nature of fractal dimension. We expect this paper could make the fractal theory understood comprehensively, and could expand fractal application properly in more and more fields. | |||
TO cite this article:Liu Haishun,Yin Chunhao,Miao Xiexing. The Correlation between Fractal Dimension of Fracture Surfaces and Mechanical Properties[OL].[24 October 2006] http://en.paper.edu.cn/en_releasepaper/content/8936 |
8. A SIMPLIFIED RESIDUAL ISI CANCELLATION METHOD FOR OFDM SYSTEM | |||
Zhi Yang,ZEMIN LIU | |||
Mechanics 07 July 2006 | |||
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Abstract:A decision-aided method is developed for the orthogonal frequency division multiplexing (OFDM) systems to eliminate the residual intersymbol interference (ISI) introduced by the channel impulse response that exceeds the length of the guard interval. The method uses the decisions to estimate the residual ISI by FFT and IFFT with a very low computational complexity, and remove the residual ISI directly. Simulations for the application of the residual ISI cancellation algorithm to the Wireless LAN system based on IEEE Std 802.11a are performed. The simulation results show that the residual ISI cancellation algorithm provides good performance improvements on static fading ISI channels. | |||
TO cite this article:Zhi Yang,ZEMIN LIU. A SIMPLIFIED RESIDUAL ISI CANCELLATION METHOD FOR OFDM SYSTEM[OL].[ 7 July 2006] http://en.paper.edu.cn/en_releasepaper/content/7500 |
9. Evaluating Orthogonal Random Variables in Non-Gaussian Karhunen-Loeve Expansion | |||
Huang Shuping | |||
Mechanics 19 April 2006 | |||
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Abstract:A simulation algorithm is developed for generating non-Gaussian processes with a specified marginal distribution function and covariance function, especially for highly skewed non-Gaussian process. It is based on the Karhunen-Loeve (K-L) expansion in terms of deterministic orthogonal functions and uncorrelated K-L random variables. The deterministic functions are obtained from the spectral decomposition of the covariance function. For non-Gaussian processes, the distributions of the K-L variables are however unknown. The strategy for determining these unknown K-L distributions is given below. The validity of the proposed algorithm for simulating highly skewed non-Gaussian process is illustrated using numerical examples. | |||
TO cite this article:Huang Shuping . Evaluating Orthogonal Random Variables in Non-Gaussian Karhunen-Loeve Expansion[OL].[19 April 2006] http://en.paper.edu.cn/en_releasepaper/content/6315 |
10. Nanosolid: Hard Shells Melt Easier | |||
Sun Changqing | |||
Mechanics 19 April 2006 | |||
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Abstract:Mechanism is presented for the facscinating facts thatthe surface shell of a nanosolid is harder at temaperature far below the melting point and the hard surface shell melts easier. | |||
TO cite this article:Sun Changqing. Nanosolid: Hard Shells Melt Easier[OL].[19 April 2006] http://en.paper.edu.cn/en_releasepaper/content/6311 |
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