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Theoretical & applied mechanics Letters 2011年第6期1卷 75-80页

作者： Zhitao Xiao,1 Liya Wang,1 He Gong,1, ) Dong Zhu,2, ) and Xizheng.Zhang3 1)Department of eng.neering mechanics, Jilin University, Changchun 130012, China 2)Department of Orthopaedic Trauma No.1, Hospital of Jilin University, Changchun 130012, China 3)Institute of Medical Equipment, Academy of Military Medical Sciences, Tianjin 300161, China Jilin Univ Dept Engn Mech Changchun 130012 Jilin Peoples R China Hosp Jilin Univ Dept Orthopaed Trauma 1 Changchun 130012 Jilin Peoples R China Acad Mil Med Sci Inst Med Equipment Tianjin 300161 Peoples R China

This paper establishes a non-linear finite element model (NFEM) of L4-L5 lumbar spinal segment with accurate three-dimensional solid ligaments and intervertebral disc. For the purpose, the intervertebral disc and surrounding ligaments are modeled with four-nodal three-dimensional tetrahedral elements with hyper-elastic material properties. Pure moment of 10 N·m without preload is applied to the upper vertebral body under the loading conditions of lateral bending, backward extension, torsion, and forward flexion, respectively. The simulate relationship curves between generalized forces and generalized displacement of the NFEM are compared with the in vitro experimental result curves to verify NFEM. The verified results show that: (1) The range of simulated motion is a good agreement with the in vitro experimental data; (2) The NFEM can more effectively reffect the actual mechanical properties than the FE model using cable and spring elements ligaments; (3) The NFEM can be used as the basis for further research on lumbar degenerative diseases.

关键词： lumbar spine non-linear ligaments finite element analysis

A statistical mechanics model of carbon nanotube macro-films

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Theoretical & applied mechanics Letters 2011年第4期1卷 19-22页

作者： Y.An,1 X.Li,2 B.Q.Wei,2 and H.Jiang 1,a) 1) School for eng.neering of Matter,Transport,and Energy,ArizonaStateUniversity,Tempe,AZ 85287,USA 2) Department of mechanical eng.neering,University of Delaware,Newark,DE 19716,USA Arizona State Univ Sch Engn Matter Transport & Energy Tempe AZ 85287 USA Univ Delaware Dept Mech Engn Newark DE 19716 USA

Carbon nanotube macro-films are two-dimensional films with micrometer thickness and centimeter by centimeter in-plane *** carbon nanotube macroscopic assemblies have attracted significant attention from the material and mechanics communities recently because they can be easily handled and tailored to meet specific eng.neering *** paper reports the experimental methods on the preparation and characterization of single-walled carbon nanotube macro-films,and a statistical mechanics model on the deformation behavior of this *** model provides a capability to optimize the synthesis process by comparing with the experiments.

关键词： carbon nanotube macro-films statistical mechanics model

Displacement fields denoising and strains extraction by finite element method

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Theoretical & applied mechanics Letters 2011年第1期1卷 18-21页

作者： B.Q.Guo,~(1,a)) H.M.Xie,~(1,b)) Y.J.Li,~1P.W.Chen,~2and Q.M.Zhang~2 1) AML,Department of eng.neering mechanics,Tsinghua University,Beijing 100084,China 2) State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,Beijing 100081, China Tsinghua Univ AML Dept Engn Mech Beijing 100084 Peoples R China Beijing Inst Technol State Key Lab Explos Sci & Technol Beijing 100081 Peoples R China

Optical full-field measurement methods are now widely applied in various domains. In general,the displacement fields can be directly obtained from the measurement,however in mechanical analysis strain fields are *** extract strain fields from noisy displacement fields is always a challeng.ng *** this study,a finite element method for smoothing displacement fields and calculating strain fields is *** experimental test case on a holed aluminum specimen under tension is applied to validate this *** heterogeneous displacement fields are measured by digital image correlation(DIC).By this proposed method,the result shows that the measuring noise on experimental displacement fields can be successfully removed,and strain fields can be reconstructed in the arbitrary area.

关键词： noisy data smoothing strain differentiation finite element method

Longitudinal waves in one dimensional non-uniform waveguides

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Theoretical & applied mechanics Letters 2011年第2期1卷 33-36页

作者： Shuqi Guo,~(1,a) Zhi Zhang,~2 and Shaopu Yang~3 1)Department of mechanics,Shijiazhuang Tiedao University,Shijiazhuang 050043,China. 2)School of Civil eng.neering,Shijiazhuang Tiedao University,Shijiazhuang 050043,China 3)School of mechanical eng.neering,Shijiazhuang Tiedao University,Shijiazhuang 050043,China Shijiazhuang Tiedao Univ Dept Mech Shijiazhuang 050043 Hebei Peoples R China Shijiazhuang Tiedao Univ Sch Civil Engn Shijiazhuang 050043 Hebei Peoples R China Shijiazhuang Tiedao Univ Sch Mech Engn Shijiazhuang 050043 Hebei Peoples R China

Wave approach is used to analyze the longitudinal wave motion in one dimensional non-uniform *** assumptions of constant wave velocity and no wave conversion,there exist four types of non-uniform rods and corresponding traveling wave solutions are *** obtained results indicate that the kinetic energy is preserved as a constant and the wave amplitude is inversely proportional to square root of the cross-sectional area of the *** certain condition,there exists a cut-off frequency for the rod with variation in geometric or material properties,below which waves do not propagate along the non-uniform *** the rod with arbitrary variable cross-section, the conclusions are similar if the wave frequency is high *** a series solution of the wave motion is presented.

关键词： longitudinal wave traveling solution cut-off frequency non-uniform rod

The pre-stack migration imaging technique for damages identification in concrete structures

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Theoretical & applied mechanics Letters 2011年第5期1卷 18-21页

作者： Ying Luo,1,Ziping Wang,1,Baiqiang Xu,1,2,and Fuhgwo Yuan 1,3,1) Key Laboratory for mechanical Structure Damage Detection Technology of China Machinery Industry Federation,Jiangsu University,Zhenjiang 210013,China 2) Faculty of Science,Jiangsu University,Zhenjiang 210013,China 3) Department of mechanical and Aerospace eng.neering,North Carolina State University,Raleigh NC 27695-7921,USA Jiangsu Univ Key Lab Mech Struct Damage Detect Technol China M Zhenjiang 210013 Peoples R China Jiangsu Univ Fac Sci Zhenjiang 210013 Peoples R China North Carolina State Univ Dept Mech & Aerosp Engn Raleigh NC 27695 USA

Pre-stack migration imaging (PMI) method,which is used in geophysical exploration by the performance of single side detection and visually display,can be used to identify the location,orientation,and severity of damages in concrete *** particular,this letter focuses on the experimental study by using a finite number of sensors for further practical applications.A concrete structure with a surface-mounted linear PZT transducers array is *** types of damages,horizontal,dipping and V-shaped crack damage,have been studied.A pre-stack reverse time migration technique is used to back-propagate the scattering waves and to image damages in concrete *** migration results from the scattering waves of an artificial damage are *** is shown that the existence of the damage in concrete structure is correctly revealed through migration process.

关键词： ultrasonic waves PMI damage identification

Analysis of a piezoelectric screw dislocation inside an elliptical inhomogeneity with confocal rigid line in piezoelectric material

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Theoretical & applied mechanics Letters 2011年第6期1卷 10-13页

作者： Chunzhi Jiang,1,2,3, ) Chao Xie,1,2 Youwen Liu,1,2 and Xin Zeng.,2 1)State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China 2)College of mechanical and Vehicle eng.neering, Hunan University, Changsha 410082, China 3)Department of Physics and Electronic Information eng.neering, Xiangnan University, Chenzhou 423000, China Hunan Univ State Key Lab Adv Design & Mfg Vehicle Body Changsha 410082 Hunan Peoples R China Hunan Univ Coll Mech & Vehicle Engn Changsha 410082 Hunan Peoples R China Xiangnan Univ Dept Phys & Elect Informat Engn Chenzhou 423000 Peoples R China

This paper deals with the electro-elastic coupling interaction between a piezoelectric screw dislocation which is located inside the elliptical inhomogeneity and an electrically conductive confocal rigid line under remote anti-plane shear stresses and in-plane electrical loads in piezoelectric composite material. The analytical-functions of the complex potentials, stress fields and the image force acting on the piezoelectric screw dislocation are obtained based on the principle of conformal mapping, the method of series expansion, the technical of analytic continuation and the analysis of singularity of complex potentials. The rigid line and the piezoelectric material property combinations upon the image force and the equilibrium position of the dislocation are discussed in detail by the numerical computation.

关键词： complex variable method rigid line piezoelectric material piezoelectric screw dislocation elliptical inhomogeneity