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Computers, Materials & Continua 2025年第1期82卷 193-222页

作者： Huilin Jia Shanqiao Huang Zifeng Yuan HEDPS Center for Applied Physics and Technology(CAPT)Department of Mechanics and Engineering SciencePeking UniversityBeijing100871China State Key Laboratory for Turbulence and Complex Systems Peking UniversityBeijing100871China

In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational *** method is based on the reduced-order homogenization(ROH)*** ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization *** to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained *** the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive *** method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical *** approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading *** sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic ***,the model is validated against experimental measurements,confirming its accuracy and reliability.

关键词： Homogenized relaxation modulus viscoelastic standard solid model reduced order homogenization fibrous composite material

Design of experiments for determination of influence of different parameters on mechanical properties of semi-solid extruded parts

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中国有色金属学会会刊：英文版 2010年第S3期20卷 794-797页

作者： V.POUVAFAR S.A.SADOUGH F.HOSSEINJ M.R.RAHMANI center of excellence in solid mechanics Mechanical Engineering DepartmentAmirKabir University of Technology(Tehran Polytechnic)

Near net-shape production of complex parts with higher mechanical properties is one of the most important final goals of the recent researches on the semi-solid *** the knowledge of the influence of every parameter on the properties of final parts is the key in the production of high quality complex *** these parameters forming temperature and velocity,and reheating and holding times have the greatest effects on the final mechanical properties of the *** influence of the parameters of non-dendritic billet production,forming speed,temperature and holding time on the properties of semi-solid extruded parts were ***-slope method was employed in order to produce non-dendritic *** material used was A356 aluminum *** the number of the parameters influencing the final properties of the parts was high(these parameters include:cooling slope angle,ram velocity,temperature and holding time),the final number of the experiments required would be n4,in which n is the number of the states of the parameters(5 in our case).In order to reduce this amount,design of experiments Tachuchi method was employed(design L25).Using this method the number of required experiments was reduced to *** the experiments the prepared semi-solid samples were extruded under isothermal condition and with 5 different ram *** tensile tests were conducted on the extruded parts and the mechanical properties of the parts were *** obtained results analyzed with MiniTab and the influence of each of the parameters and also the percentage of its influence were *** an optimum region for the parameters was *** temperature,ram speed,slope angle and holding time have more important effects descendingly.

关键词： semi-solid extrusion Tachuchi method A356 alloy mechanical properties

Coupled hydroelastic vibrations of an elliptical cylindrical tank with an elastic bottom

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Journal of Hydrodynamics 2014年第2期26卷 264-276页

作者： HASHEMINEJAD Seyyed M. TAFANI Mostafa Acoustics Research Laboratory Center of Excellence in Experimental Solid Mechanics and Dynamics School of Mechanical Engineering Iran University of Science and Technology

An exact three-dimensional analysis based on the linear potential theory and the elaborated method of eigenfunction expansion in elliptic coordinates are presented to study the free coupled elasto-hyrodynamic characteristics of an upright non-deformable cylindrical container of elliptical planform with a flexible bottom plate, filled to an arbitrary depth with an inviscid incompressible liquid. Extensive numerical data are presented in an orderly fashion for the first few symmetric/anti-symmetric coupled hydroelastic natural frequencies as a function of fluid depth parameter for two plate aspect ratios. Also, selected hydrodynamic and structural deformation modes shapes are presented in graphical form. The effects of liquid level, bottom plate elasticity, and cross sectional aspect ratio on the sloshing frequencies and hydrodynamic pressure modes are examined. The validity of the results is examined through computations using a commercial finite element package as well as by comparison with the data available in literature.

关键词： exact solution fluid-structure interaction free surface oscillations vertical elliptical vessel Mathieu functions

3D Micromechanical Modeling of Failure and Damage Evolution in Dual Phase Steel Based on a Real 2D Microstructure

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Acta Mechanica solida Sinica 2016年第1期29卷 95-110页

作者： M.R.Ayatollahi A.Ch.Darabi H.R.Chamani J.Kadkhodapour Fatigue and Fracture Lab. Center of Excellence in Experimental Solid Mechanics and DynamicsSchool of Mechanical EngineeringIran University of Science and Technology

A plate of dual phase steel was produced from low carbon steel with intercritical annealing treatment. Its optically determined surface microstructure was utilized to construct three different microstructural models. To describe the ductile damage in the ferritic matrix, the Gurson-Tvergaard-Needleman model was used with the failure in the martensite phase being ignored. The numerical results obtained for the mechanism of void initiation and coalescence were compared with the experimental observations. The numerical results obtained from the randomly extruded 3D model showed a significantly better agreement with the experimental ones than those obtained from the 2D model or the uniformly extruded 3D model.

关键词： dual phase steel 3D model microstructure micromechanical modeling GTN dam-age model

Exact Geometric Relationships, Symmetry Breaking and Structural Stability for Single-Walled Carbon Nanotubes

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Nano-Micro Letters 2011年第4期3卷 228-235页

作者： Tong Zhang Ze Shuai Yuan Li Hao Tan Research center for solid mechanics Beihang University

We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.

关键词： Geometry Structural Stability Symmetry Breaking Fractal Dimension

Analytical dynamic model of elastic-plastic pipe-on-pipe impact

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Applied Mathematics and mechanics(English Edition) 2013年第6期34卷 731-746页

作者：闫冬梅孙玉鑫杨嘉陵 solid mechanics Research center Beihang University

Abstract The dynamic response of pipe-on-pipe impact is described by an analytical model. The model considers the impact of a whipping pipe with one end hinged and the other end free on a simply-supported target pipe at its midpoint. Combining with the contact theory, the Laplace transformation, and the inverse Laplace transformation method, an analytical model based on the tubular beam theory is proposed to study the elastic-plastic behavior of a target pipe laterally impacted by a whipping pipe. Numerical simulations using the explicit finite element code MSC/DYTRAN are also performed. The results are coincident with the theoretical prediction.

关键词： pipe impact dynamic response Laplace transformation analytical model

Closed form solutions for free vibrations of rectangular Mindlin plates

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Acta Mechanica Sinica 2009年第5期25卷 689-698页

作者： Yufeng Xing Bo Liu The solid mechanics Research center, Beihang University,100191 Beijing, China The solid mechanics Research center Beihang University Beijing China

A new two-eigenfunctions theory, using the amplitude deflection and the generalized curvature as two fundamental eigenfunctions, is proposed for the free vibration solutions of a rectangular Mindlin plate. The three classical eigenvalue differential equations of a Mindlin plate are reformulated to arrive at two new eigenvalue differential equations for the proposed theory. The closed form eigensolutions, which are solved from the two differential equations by means of the method of separation of variables are identical with those via Kirchhoff plate theory for thin plate, and can be employed to predict frequencies for any combinations of simply supported and clamped edge conditions. The free edges can also be dealt with if the other pair of opposite edges are simply supported. Some of the solutions were not available before. The frequency parameters agree closely with the available ones through pb-2 Rayleigh-Ritz method for different aspect ratios and relative thickness of plate.

关键词： Mindlin plate Free vibration Closed form solution Separation of variable

INFLUENCE OF THE MIDDLE WEAK LAYER ON THE IMPACT BEHAVIOR OF LAMINATED STRUCTURES

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Acta Mechanica solida Sinica 2013年第3期26卷 263-276页

作者： Dongfang Wang Jialing Yang Yuxin Sun The solid mechanics Research center Beijing University of Aeronautics and Astronautics

In this paper, a calculation model based on the subsection displacement theory and the large deflection analysis is developed to describe the dynamic response of isotropic laminated circular plates impacted by a soft body. The model takes into account the interlaminar shear effect induced by the middle weak layer. It is proved by numerical examples that the difference between the model developed in this paper and that based on the classical laminated theory mainly depends on three factors, the elastic modulus of the glue, the radius of the circular plate and the impact force.

关键词： laminated glass interlaminar shear stress subsection displacement theory lami-nated circular plate

An eigenelement method and two homogenization conditions

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Acta Mechanica Sinica 2009年第3期25卷 345-351页

作者： Yufeng Xing Xingming Wang The solid mechanics Research center, Beihang University, 100083 Beijing, China The solid mechanics Research center Beihang University Beijing China

Under inspiration from the structure-preserving property of symplectic difference schemes for Hamiltonian systems, two homogenization conditions for a representative unit cell of the periodical composites are proposed, one condition is the equivalence of strain energy, and the other is the deformation similarity. Based on these two homogenization conditions, an eigenelement method is presented, which is characteristic of structure-preserving property. It follows from the frequency comparisons that the eigenelement method is more accurate than the stiffness average method and the compliance average method.

关键词： Composites Homogenization ,The equivalence of strain energy Deformation similarityEigenelement method

New exact solutions for free vibrations of rectangular thin plates by symplectic dual method

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Acta Mechanica Sinica 2009年第2期25卷 265-270页

作者： Y. Xing B. Liu The solid mechanics Research center, Beihang University, 100083 Beijing, China The solid mechanics Research center Beihang University Beijing China

The separation of variables is employed to solve Hamiltonian dual form of eigenvalue problem for transverse free vibrations of thin plates, and formulation of the natural mode in closed form is performed. The closed-form natural mode satisfies the governing equation of the eigenvalue problem of thin plate exactly and is applicable for any types of boundary conditions. With all combinations of simplysupported （S） and clamped （C） boundary conditions applied to the natural mode, the mode shapes are obtained uniquely and two eigenvalue equations are derived with respect to two spatial coordinates, with the aid of which the normal modes and frequencies are solved exactly. It was believed that the exact eigensolutions for cases SSCC, SCCC and CCCC were unable to be obtained, however, they are successfully found in this paper. Comparisons between the present results and the FEM results validate the present exact solutions, which can thus be taken as the benchmark for verifying different approximate approaches.

关键词： Classical theory of thin plate Frequency Free vibrations Symplectic dual method Exact solution