Archives of Mechanics最新文献_第7页

Combined bending-tension/compression deformation of micro-bars accounting for strain-driven long-range interactions 考虑应变驱动的远程相互作用的微杆弯曲-拉伸/压缩组合变形

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2019-02-27 DOI: 10.24423/AOM.3031

N. Zhang, J. Yan, C. Li, J. Zhou

{"title":"Combined bending-tension/compression deformation of micro-bars accounting for strain-driven long-range interactions","authors":"N. Zhang, J. Yan, C. Li, J. Zhou","doi":"10.24423/AOM.3031","DOIUrl":"https://doi.org/10.24423/AOM.3031","url":null,"abstract":"The paper aims to investigate combined bending-tension/compression deformation of a micro-bar. The strain-driven nonlocal differential model which involves information about long-range interactions between atoms is used to develop the mechanical model and theoretical formulations. Subsequently, effects of internal long-range scale parameter, length of micro-bar, external loads and bending rigidity on combined deformation are shown and discussed. In particular, the upper bound of internal longrange scale parameter and the buckling load are achieved during bending-compression analyses. It is demonstrated that the existence of internal scale parameter or axial tensile load decreases combined deformation. The deflection at the midpoint reduces with increasing bending rigidity, while it rises with increasing length of the microbar. Additionally, an effect of the acting position of transverse load on combined deformation is discussed and deflection at the symmetry point of transverse acting position is achieved. When the long-range interaction is taken into consideration, the equivalent stiffness of the micro-bar subjected to combined bending-tension is stiffer than that predicted by classical mechanics, and it validates the existing nonlocal hardening model. The combined bending-compression of the micro-bar reveals that the deflection may increase or decrease with an increase in the long-range scale or structural length, which verifies both the nonlocal softening and hardening models.","PeriodicalId":8280,"journal":{"name":"Archives of Mechanics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68938892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

MHD natural convection in saturated porous media with heat generation/absorption and thermal radiation: closed-form solutions 饱和多孔介质中的MHD自然对流，具有热产生/吸收和热辐射:闭式溶液

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2019-02-27 DOI: 10.24423/AOM.3049

M. Turkyilmazoglu

{"title":"MHD natural convection in saturated porous media with heat generation/absorption and thermal radiation: closed-form solutions","authors":"M. Turkyilmazoglu","doi":"10.24423/AOM.3049","DOIUrl":"https://doi.org/10.24423/AOM.3049","url":null,"abstract":"The present work is devoted to the free convection flow occurring about a heated vertically stretching permeable surface placed in a porous medium under the influence of a temperature dependent internal heat generation or absorption. There are volume radiative heat sources in the fluid and the system is permeated by a uniform magnetic field. It is shown that the governing equations are reducible to a self-similar nonlinear ordinary differential equation of third order whose solutions are constructed analytically in the purely exponential series form. Under special circumstances, closed-form solutions are available which clearly indicate the existence of dual natural convection solutions. Otherwise, analytical solutions are still possible which are shown to be computed from an elegant algorithm without a need to invoke any numerical means. Exact solutions demonstrate, in physical insight that, in the presence of a heat sink absorbing the temperature from the porous medium increases the rate of heat transfer from the wall, whereas a heat source mechanism will surely overheat the system during the wall heating process, resulting in poor heat transfer rates. The presented exact solutions are beneficial for investigation of free convection phenomena in different geometries taking into account more complex physical features in higher dimensions.","PeriodicalId":8280,"journal":{"name":"Archives of Mechanics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2019-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68938430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 44

State-dependent fractional plasticity model for the true triaxial behaviour of granular soil 颗粒土真三轴特性的状态依赖分数塑性模型

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2019-02-27 DOI: 10.24423/AOM.3084

Y. Sun, W. Sumelka

引用次数: 15

Influence of initial density of granular stack on transient regime of homogeneous fluidization 颗粒堆初始密度对均匀流化过渡状态的影响

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2019-02-05 DOI: 10.24423/AOM.3057

A. Drame, L. Wang, B. Diourte

引用次数: 0

Mathematical modeling and stochastic stability analysis of viscoelastic nanobeams using higher-order nonlocal strain gradient theory 基于高阶非局部应变梯度理论的粘弹性纳米梁的数学建模与随机稳定性分析

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2019-02-05 DOI: 10.24423/AOM.3139

I. Pavlović, R. Pavlović, G. Janevski

引用次数: 6

Stability of feed forward artificial neural networks versus nonlinear structural models in high speed deformations: A critical comparison 前馈人工神经网络与非线性结构模型在高速变形中的稳定性：一个关键的比较

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2019-02-05 DOI: 10.24423/AOM.3091

M. Stoffel, F. Bamer, B. Markert

引用次数: 6

Potential method in the theory of thermoelasticity for materials with triple voids 三重空隙材料热弹性理论中的势方法

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2019-02-05 DOI: 10.24423/AOM.3118

M. Svanadze

引用次数: 7

Subtle structure of streamers under conditions resembling those of Transient Luminous Events 类似瞬态发光事件条件下飘带的微妙结构

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2018-12-23 DOI: 10.24423/AOM.3009

J. Blecki, K. Mizerski

{"title":"Subtle structure of streamers under conditions resembling those of Transient Luminous Events","authors":"J. Blecki, K. Mizerski","doi":"10.24423/AOM.3009","DOIUrl":"https://doi.org/10.24423/AOM.3009","url":null,"abstract":"The paper presents a brief review of the observational facts related to plasma filamentation in astrophysics and the subtle structures of plasma in Transient Luminous Events (TLE’s) and an analysis of the physical mechanism that could contribute to formation of filaments in plasma inside streamers. The values of physical parameters are assumed such as to resemble the physical conditions in streamers of the TLE’s. Estimates of the typical spatial scales of these structures and temporal characteristics of filament formation are given. The analysis concerns a non-magnetic mechanism based on a form of non-relativistic dissipative instability and the electron-nitrogen collisional 2 Π g resonance. It is argued that the influence of the magnetic field is negligible at the leading order at least up to the altitudes of about 65–70 km. Under the conditions related to those in plasma inside the TLE’s, derived based on the current knowledge of physical parameters within the electric discharges, the identified dissipative-resonant instability is demonstrated to be the only/most vigorous linear instability developing in the system. It results in periodic plasma density distribution in the direction transverse to the electric field. The obtained time scales of the instability development are quick and proportional to the inverse of the ion-neutral collision frequency, 1/ ν i , whereas the proposed spatial scale of the density stripes/filaments is proportional to the electron temperature and inversely proportional to the speed of the discharge.","PeriodicalId":8280,"journal":{"name":"Archives of Mechanics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2018-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49469404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

LES study of turbulence intensity impact on spark ignition in a two-phase flow 湍流强度对两相流火花点火影响的LES研究

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2018-12-23 DOI: 10.24423/AOM.3018

J. Stempka, L. Kuban, A. Tyliszczak

{"title":"LES study of turbulence intensity impact on spark ignition in a two-phase flow","authors":"J. Stempka, L. Kuban, A. Tyliszczak","doi":"10.24423/AOM.3018","DOIUrl":"https://doi.org/10.24423/AOM.3018","url":null,"abstract":"The paper presents large eddy simulation (LES) study aiming at investigations of an influence of flow conditions on a spark ignition process in a two-phase shear dominated flow. Implicit LES approach is applied for the combustion modelling and the spark is modelled using the energy deposition model of Lacaze et al. [20]. We examine an impact of turbulence intensities and randomness of initial distributions of velocity fluctuations on a flame development during the spark duration and shortly after it is switched off. It is found that for a strong spark, as used in IC engines, the turbulence intensity has little effect on the ignition and flame kernel growth and no significant differences are seen even if the turbulence intensities differ four times. It is observed that weak turbulent structures cannot affect fast flame propagation mechanism and its development is conditioned by evaporation and rapid thermal expansion. In such regimes, the turbulence seems to be too weak to significantly alter the flame dynamics. It is found that at the initial stage of the flame development it grows toward the fuel-rich region and spread over the fuel-lean side only after the evaporated fuel diffuses and mixes with the oxidizer stream. The flame size and its shape turn out to be equally dependent on the initial distribution of the turbulence fluctuations and turbulence intensity.","PeriodicalId":8280,"journal":{"name":"Archives of Mechanics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2018-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42564960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Free in-plane and out-of-plane vibrations of rotating thin ring based on the toroidal shell theory 基于环面壳理论的旋转薄环面内、面外自由振动

IF 0.8 4区工程技术

Archives of Mechanics Pub Date : 2018-10-30 DOI: 10.24423/aom.3013

I. Senjanović, I. Čatipović, N. Alujevic, D. Čakmak, N. Vladimir

{"title":"Free in-plane and out-of-plane vibrations of rotating thin ring based on the toroidal shell theory","authors":"I. Senjanović, I. Čatipović, N. Alujevic, D. Čakmak, N. Vladimir","doi":"10.24423/aom.3013","DOIUrl":"https://doi.org/10.24423/aom.3013","url":null,"abstract":"In this paper rigorous formulae for natural frequencies of in-plane and out-of-plane free vibrations of a rotating ring are derived. An in-plane vibration mode of the ring is characterised by coupled flexural and extensional deformations, whereas an out-of-plane mode is distinguished by coupled flexural and torsional deformations. The expressions for natural frequencies are derived from a generalised toroidal shell theory. For the in-plane vibrations, the ring is considered to be a short top segment of a toroidal shell. For the out-of-plane vibrations, the ring is considered to be a side segment of the shell. Natural vibrations are analysed by the energy approach. The expressions for the ring strain and kinetic energies are deduced from the corresponding expressions for the torus. It is shown that the ring rotation causes bifurcation of natural frequencies of the in-plane vibrations only. Bifurcation of natural frequencies of the out-of-plane vibrations does not occur. Otherwise, for non-rotating rings, the derived formulae for the natural frequencies of the in-plane and the out-of-plane flexural vibrations are very similar. The derived analytical results are validated by a comparison with FEM and FSM (Finite Strip Method) results, as well as with experimental results available in the literature.","PeriodicalId":8280,"journal":{"name":"Archives of Mechanics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2018-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42287626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3