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Scattering of harmonic P1 and SV waves by a shallow lined circular tunnel in a poroelastic half-plane

SOIL DYNAMICS AND EARTHQUAKE ENGINEERING 2022年 158卷 1页

作者： Liu, Qijian Yue, Cheng Zhao, Mingjuan Hunan Univ Coll Civil Engn Changsha 410082 Hunan Peoples R China Hunan Univ Key Lab Bldg Safety & Energy Efficiency Minist Educ Changsha 410082 Hunan Peoples R China Delft Univ Technol Fac Civil Engn & Geosci NL-2600 GA Delft Netherlands

An analytical solution for the scattering of harmonic P1 and SV waves in a poroelastic half-plane with a shallow lined tunnel is obtained using the plane complex theory in elastodynamics. In light of the wave function expansions, the wave fields of the poroelastic medium and the liner with unknown coefficients are obtained based on Biot's theory and Helmholtz decomposition. complex-valued expressions of the effective stresses, the fluid stress, and the displacements of the poroelastic medium and the liner are expressed by the complex variable function method and the conformal transformation technique. With the boundary conditions and the continuity of the medium-liner interface, the boundary value problem results in a series of algebraic equations. The unknown coefficients in the infinite set of algebraic equations can be solved numerically by truncating the series number. A parametric study for the incident SV waves is performed to investigate dynamic stress concentrations and fluid stress of the medium and the liner. Numerical results show that the embedment depth of the tunnel, the incident angle of the excitations, and the porosity of the medium have considerable influence on the dynamic responses of the medium and the liner. The shielding effect of the tunnel on the incident SV waves is obvious. For the big embedment depth of the tunnel, the scattered waves contribute little to the displacements and dynamic stress concentration of the medium and the liner. For a high porosity close to the critical value, the response of the medium-liner system to the incident waves is great.

关键词： Wave scattering Poroelastic half-plane Lined tunnel complex variable method Conformal mapping

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Torsion problem for a bar composed of confocally elliptical dissimilar layers

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ARCHIVE OF APPLIED MECHANICS 2020年第3期90卷 623-633页

作者： Chen, Y. Z. Jiangsu Univ Div Engn Mech Zhenjiang Jiangsu Peoples R China

This paper provides a general solution for a torsion problem of bar composed of confocally elliptical dissimilar layers. complex variable method is used to study the problem. The continuity conditions for the warping function and the normal shear stress along the interfaces are suggested. By using the transfer matrices, we can exactly link all sets of undetermined coefficients in the complex potentials defined for layers. Finally, from the conditions imposed on the interior inclusion and the exterior boundary, the solution is obtainable. Numerical examples are carried out to show the influence of the different shear moduli defined on different layers to the stress distribution. The applied torque at the ends of bar is evaluated.

关键词： Torsion problem Bar composed of confocally elliptical dissimilar layers complex variable method Transfer matrix method

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Analytical Thermal Stress Analysis of Perforated Symmetric Composite Laminates Containing a Quasi-Triangular Hole

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PHYSICAL MESOMECHANICS 2020年第6期23卷 514-530页

作者： Bayati Chaleshtari, M. H. Khoramishad, H. Berto, F. Iran Univ Sci & Technol Sch Mech Engn Tehran 16846 Iran Norwegian Univ Sci & Technol Dept Mech & Ind Engn N-7491 Trondheim Norway

In this study, the thermal stress distribution surrounding a quasi-triangular hole within a symmetric composite laminate made of various composite materials was investigated. A composite laminate exposed to uniform heat flux was analyzed using the complex variable method as a thermo-elastic two-dimensional problem under a steady state condition. The analytical solution was achieved with the development of the Lekhnitskii's solution and using the classical laminated plate theory and a conformal mapping function. The influence of important parameters on thermal stress distribution surrounding a hole such as the hole orientation, bluntness and aspect ratio, the heat flux angle and the laminate stacking sequence and material was studied. The results were achieved for different stacking sequences of [45 degrees/-45 degrees](s) and [0 degrees/90 degrees](s). The analytical solution in this study was well validated against the finite element results.

关键词： complex variable method Quasi-triangular hole Symmetric laminated composite Thermal stress Stacking sequence

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Effect of nanotwin and dislocation pileup at twin boundary on dislocation emission from an interfacial collinear crack tip in nanocrystalline bimaterials

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MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 2020年第12期27卷 965-974页

作者： Peng, Xianghua Yu, Min Liu, Youwen Cent South Univ Forestry & Technol Swan Coll Changsha Peoples R China Cent South Univ Forestry & Technol Coll Civil Engn Changsha Peoples R China Hunan Univ State Key Lab Adv Design & Mfg Vehicle Body Changsha Peoples R China

The interaction between nanotwin and dislocation pileup at twin boundary and interface cracks are of vital importance in studying the toughening mechanism of nanocrystalline materials. We have developed a theoretical model to discuss the effects of nanotwin and dislocation pileup on dislocation emission from an interfacial collinear crack tip in nanocrystalline bimaterials. The nanotwin as a stress source can be descripted by two disclination dipoles, and some dislocations produced by the grain boundary pile up at twin boundary. Using the complex potential method, the complex form of dislocation force and critical stress intensity factors (SIFs) corresponding to dislocation emission under remote plane loadings are deduced. Through numerical analysis, it is discussed that the effects of twin strength, twin orientation, twin size, twin position, dislocation pileup, crack length, and material constant on the critical SIF corresponding to dislocation emission in detail. The results show that the nanoscale twin and the dislocation pileup at the twin boundary will hinder dislocation emitted from the collinear crack tip and reduce toughness caused by dislocation emission. There is a critical nanotwin size making the critical SIF equal to zero and a best twin position minimizing the value of the critical SIF making dislocations emission easiest. The shear modulus of the two half plane have great influence on the critical SIF.

关键词： Dislocation emission stress intensity factor nanocrytalline bi-materials nanotwin dislocation pileup complex variable method

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In-plane stress analysis of two nanoscale holes under surface tension

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ARCHIVE OF APPLIED MECHANICS 2020年第6期90卷 1363-1372页

作者： Wang, Shuang Yang, Hai-Bing Gao, Cunfa Chen, Zengtao Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Mech Struct Nanjing 210016 Peoples R China Univ Alberta Dept Mech Engn Edmonton AB T6G 1H9 Canada South China Univ Technol Sch Civil Engn & Transportat Dept Mech Engn Guangzhou 510641 Peoples R China

Studied in this paper is the surface tension-induced stress field around two nanoscale holes in an infinite, elastic matrix. The complex variable method is adopted to describe the assumed plane-strain deformation of the structure. The stress boundary conditions at the surfaces of the holes are formulated via the integral-type Gurtin-Murdoch model. The stress field is finally obtained with the aid of conformal mapping and series expansion methods. Numerical examples are demonstrated for the case of one approximately triangular, smooth hole and one approximately square, smooth hole. A detailed discussion is carried out about the influence of the distance between the two holes on the stress field.

关键词： Nanoscale holes Surface tension Two-hole problems Common shapes complex variable method

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Fracture of thermoelectric materials: An electrical and thermal strip saturation model

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ENGINEERING FRACTURE MECHANICS 2020年 235卷 107186-107186页

作者： Wang, Pan Wang, Kaifa Wang, Baolin Zhang, Chunwei Fang, Daining Beijing Inst Technol Inst Adv Struct Technol Beijing 100081 Peoples R China Harbin Inst Technol Sch Sci Shenzhen 518055 Peoples R China Univ Western Sydney Sch Engn Penrith NSW 2751 Australia Qingdao Univ Technol Sch Civil Engn Qingdao 266033 Peoples R China

Cracking is a critical issue in the preparation and application of thermoelectric materials. Traditional models for thermoelectric fracture predict infinite electric current and heat flux at the crack tip. However, it is impossible since infinite electric current and heat cannot be sustained at the atomic level. To give a physically reasonable fracture prediction of thermoelectric materials, this paper proposes an analytical model of thermoelectric fracture based on the concept of electrical and thermal field saturation along a strip at the crack front, in which we assume the electric current and heat flux cannot exceed a saturation limit. Firstly, based on the complex variable method, we derive the thermoelectric field solutions with electrical and thermal field saturation at the crack tip. Then, the thermally induced stresses and the fracture criterions are given. The results show that the thermoelectric field predicted by the saturation model exhibits no singularity at the crack tip, which may give better agreement with the experimental observations, and thus showing better application potential.

关键词： Thermoelectric materials Thermoelectric fracture complex variable method Strip saturation model

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Thermoelastic problem of two arbitrarily-shaped inclusions

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JOURNAL OF THERMAL STRESSES 2020年第12期43卷 1601-1612页

作者： Yang, Hai-Bing Qiu, Jian Tang, Jie-Yao Wang, Shuang South China Univ Technol Sch Civil Engn & Transportat Dept Mech Engn Guangzhou Peoples R China Shaoguan Univ Sch Civil Engn Shaoguan Peoples R China Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Mech Struct Nanjing Peoples R China Peking Univ Coll Engn Dept Mech & Engn Sci BIC ESATState Key Lab Turbulence & Complex Syst Beijing Peoples R China

In this paper, we study the plane thermoelastic problem of an infinite matrix containing two interacting inclusions of arbitrary shapes for a uniform heat flux applied on the matrix remotely. We propose a numerical scheme for calculating the temperature and stress fields in the inclusion-matrix system by using the principle of superposition and the Faber series method. A group of numerical examples is given to demonstrate the stress field around two soft inclusions (softer than the matrix) of triangular and square shapes. The results show that the interfacial thermal stress concentration may be relieved by improving the thermal conductivities of the soft inclusions. In particular, we find that for soft inclusions with higher thermal conductivities (higher than the matrix), the interfacial thermal stresses could even reduce slightly when the inclusions approach each other. Additionally, it is shown that the thermal load-induced interaction between the inclusions decays much slower than the mechanical load-induced interaction between the inclusions as the inclusions move away from each other.

关键词： Thermal stress concentration two inclusions arbitrary shapes complex variable method

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Thermal stress distribution around a thermally-insulated polygonal cutout in graphite/epoxy composite laminates under heat flux

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Journal of Central South University 2021年第11期28卷 3418-3433页

作者： Mohammad Hossein BAYATI CHALESHTARI Hadi KHORAMISHAD School of Mechanical Engineering Iran University of Science and TechnologyNarmakTehran 16846Iran

In this study,the effect of influencing parameters on the stress distribution around a polygonal cutout within a laminated composite under uniform heat flux was analytically *** analytical method was developed based on the classical laminated plate theory and two-dimensional thermo-elastic method.A mapping function was employed to extend the solution of a perforated symmetric laminate with a circular cutout to the solution of polygonal *** effect of significant parameters such as the cutout angular position,bluntness and aspect ratio,the heat flux angle and the laminate stacking sequence in symmetric composite laminate containing triangular,square and pentagonal cutouts was *** Neumann boundary condition was used at the edges of the thermally insulated polygonal *** laminate was made of graphite/epoxy(AS/3501) material with two different stacking sequences of [30/45]sand[30/0/-30]_(s).The analytical solutions were well validated against finite element results.

关键词： analytical solution thermal stress analysis polygonal cutout complex variable method polymeric composite

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Uniformity of stresses inside a non-elliptical inhomogeneity near an irregularly shaped hole in plane elasticity

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MECHANICS OF MATERIALS 2020年 145卷 103389-000页

作者： Wang, Xu Schiavone, Peter East China Univ Sci & Technol Sch Mech & Power Engn 130 Meilong Rd Shanghai 200237 Peoples R China Univ Alberta Dept Mech Engn 10-203 Donadeo Innovat Ctr Engn Edmonton AB T6G 1H9 Canada

We analyze the uniformity of stresses inside a non-elliptical elastic inhomogeneity interacting with a nearby irregularly shaped hole when the surrounding matrix is subjected to uniform remote in-plane stresses. Using Muskhelishvili's complex variable formulation and the technique of conformal mapping for a doubly connected domain, we demonstrate that Eshelby's uniformity property is indeed valid when the inhomogeneity and the matrix have the same shear modulus but distinct Poisson's ratios. In this case, the shapes of the inhomogeneity and the hole are completely determined by two material, one loading and three geometric parameters.

关键词： Eshelby's uniformity property Inhomogeneity Hole Plane elasticity complex variable method Conformal mapping

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Uniformity of stresses inside a parabolic inhomogeneity

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ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK 2020年第2期71卷 1-7页

作者： Wang, Xu Schiavone, Peter East China Univ Sci & Technol Sch Mech & Power Engn 130 Meilong Rd Shanghai 200237 Peoples R China Univ Alberta Dept Mech Engn Donadeo Innovat Ctr Engn 10 203 Edmonton AB T6G 1H9 Canada

Within the context of anti-plane elasticity and plane elasticity, we prove that the stress field inside a parabolic elastic inhomogeneity still remains uniform when the surrounding matrix is subjected to uniform remote stresses. Explicit expressions are presented for the uniform stresses and rigid-body rotation inside the inhomogeneity as well as for the non-uniform stresses in the matrix.

关键词： Uniform stresses Parabolic inhomogeneity Anti-plane elasticity Plane elasticity complex variable method

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