• Title/Summary/Keyword: Thermo-mechanical properties

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Analysis of the hygro-thermo-mechanical response of functionally graded plates resting on elastic foundations based on various micromechanical models

  • Belkacem Adim;Tahar Hassaine Daouadji
    • Geomechanics and Engineering
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    • v.38 no.4
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    • pp.409-420
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    • 2024
  • In this research the hygro-thermo-mechanical loading and micromechanical model effects on bending behavior of functionally graded material plates resting on Winkler and Pasternak elastic foundations, the higher order shear deformation theory is used here. The material properties of the plate: young's modulus, thermal coefficient and moisture expansion coefficient are assumed to be graded in the thickness direction according to various micromechanical models starting with the Voigt's model which is commonly used in most functionally graded plates studies to the Reuss's, LRVE's and Mori-Tanaka's models. The principle of virtual displacement is used to determine the equilibrium equations and the a several numerical results are given to validate the precision of the present method for bending behavior of FGM plates subjected to hygro-thermo-mechanical loading resting on elastic foundations. Afterwards, a parametric study is conducted to determine the effect of different parameters on the deflection of the FGM plates like micromechanical models, type of loading and plate geometry. In the lights of the present research, it can be concluded that the present theory is accurate and simple in predicting the deflection behavior of functionally graded plates under hygro-thermo-mechanical effects and micromechanical models.

Dynamic bending response of SWCNT reinforced composite plates subjected to hygro-thermo-mechanical loading

  • Chavan, Shivaji G.;Lal, Achchhe
    • Computers and Concrete
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    • v.20 no.2
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    • pp.229-246
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    • 2017
  • The dynamic bending response of single walled carbon nanotube reinforced composite (SWCNTRC) plates subjected to hygro-thermo-mechanical loading are investigated in this paper. The mechanical load is considered as wind pressure for dynamic bending responses of SWCNTRC plate. The dynamic version of the High Order shear deformation Theory (HSDT) for a composite plate with Matrix and SWCNTRC plate is first formulated. Distribution of fibers through the thickness of the SWCNTRC plate could be uniform or functionally graded (FG). The dynamic displacement response is predicted by using Nemarck integration method. The effective material properties of SWCNTRC are estimated by using micromechanics based modeling approach. The effect of different environmental condition, volume fraction of SWCNT, Width-to-thickness ratio, wind pressure, different SWCNTRC-FG plates, boundary condition, E1/E2 ratio, different temperature on dynamic displacement response is investigated. The dynamic displacement response is compared with the available literature and it shows good agreement.

A Study on Characteristics of Jointed Rock Masses and Thermo-hydro-mechanical Behavior of Rock Mass under High Temperature (방사성 폐기물 저장을 위한 불연속 암반의 특성 및 고온하에서의 암반의 수리열역학적 상호작용에 관한 연구)

  • 이희근;김영근;이희석
    • Tunnel and Underground Space
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    • v.8 no.3
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    • pp.184-193
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    • 1998
  • In order to dispose radioactive wastes safely, it is needed to understand the mechanical, thermal, fluid behavior of rockmass and physico-chemical interactions between rockmass and water. Also, the knowledge about mechanical and hydraulic properties of rocks is required to predict and to model many conditions of geological structure, underground in-situ stress, folding, hot water interaction, intrusion of magma, plate tectonics etc. This study is based on researches about rock mechanics issues associated with a waste disposal in deep rockmass. This paper includes the mechanical and hydraulic behavior of rocks in varying temperature conditions, thermo-hydro-mechanical coupling analysis in rock mass and deformation behavior of discontinuous rocks. The mechanical properties were measured with Interaken rock mechanics testing systems and hydraulic properties were measured with transient pulse permeability measuring systems. In all results, rock properties were sensitive to temperature variation.

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Transverse cracking based numerical analysis and its effects on cross-ply laminates strength under thermo-mechanical degradation

  • Abdelatif, Berriah;Abdelkader, Megueni;Abdelkader, Lousdad
    • Structural Engineering and Mechanics
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    • v.60 no.6
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    • pp.1063-1077
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    • 2016
  • Components manufactured from composite materials are frequently subjected to superimposed mechanical and thermal loadings during their operating service. Both types of loadings may cause fracture and failure of composite structures. When composite cross-ply laminates of type [$0_m/90_n]_s$ are subjected to uni-axial tensile loading, different types of damage are set-up and developed such as matrix cracking: transverse and longitudinal cracks, delamination between disoriented layers and broken fibers. The development of these modes of damage can be detrimental for the stiffness of the laminates. From the experimental point of view, transverse cracking is known as the first mode of damage. In this regard, the objective of the present paper is to investigate the effect of transverse cracking in cross-ply laminate under thermo-mechanical degradation. A Finite Element (FE) simulation of damage evolution in composite crossply laminates of type [$0_m/90_n]_s$ subjected to uni-axial tensile loading is carried out. The effect of transverse cracking on the cross-ply laminate strength under thermo-mechanical degradation is investigated numerically. The results obtained by prediction of the numerical model developed in this investigation demonstrate the influence of the transverse cracking on the bearing capacity and resistance to damage as well as its effects on the variation of the mechanical properties such as Young's modulus, Poisson's ratio and coefficient of thermal expansion. The results obtained are in good agreement with those predicted by the Shear-lag analytical model as well as with the obtained experimental results available in the literature.

Analysis of Pressure Plate Behavior of a Clutch Including Thermal and Mechanical Material Properties (기계적 및 열적 물성을 고려한 클러치 압력판의 거동해석)

  • Hur, Man-Dae;Lee, Sang-Uk;Kim, Gug-Yong;Kang, Sung-Su
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.4
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    • pp.524-532
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    • 2009
  • In the mechanical clutches, the pressure plate is one of the important parts for transferring the power and reducing the vibration. Instead of gray and ductile irons, CGI(Compacted Graphite Cast Iron) is concerned to be the replacement recently. A thermo-mechanical coupled analysis was performed to investigate the behavior of the pressure plate for manual clutches. Thermal and mechanical properties of three kinds of cast irons were obtained from the mechanical experiments and referred other technical reports. The results of FEM analysis, were well match with the experimental ones. In this designated FEM method, temperature distribution, stress distribution and thermal deformation were successfully gained and these results will help to design the pressure plate which was made by cast irons including CGI.

Comprehensive piezo-thermo-elastic analysis of a thick hollow spherical shell

  • Arefi, M.;Khoshgoftar, M.J.
    • Smart Structures and Systems
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    • v.14 no.2
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    • pp.225-246
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    • 2014
  • The present paper develops piezo-thermo-elastic analysis of a thick spherical shell for generalized functionally graded piezoelectric material. The assumed structure is loaded under thermal, electrical and mechanical loads. The mechanical, thermal and electrical properties are graded along the radial direction based on a power function with three different non homogenous indexes. Primarily, the non homogenous heat transfer equation is solved by applying the general boundary conditions, individually. Substitution of stress, strain, electrical displacement and material properties in equilibrium and Maxwell equations present two non homogenous differential equation of order two. The main objective of the present study is to improve the relations between mechanical and electrical loads in hollow spherical shells especially for functionally graded piezoelectric materials. The obtained results can evaluate the effect of every non homogenous parameter on the mechanical and electrical components.

On scale-dependent stability analysis of functionally graded magneto-electro-thermo-elastic cylindrical nanoshells

  • Asrari, Reza;Ebrahimi, Farzad;Kheirikhah, Mohammad Mahdi
    • Structural Engineering and Mechanics
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    • v.75 no.6
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    • pp.659-674
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    • 2020
  • The present paper employs nonlocal strain gradient theory (NSGT) to study buckling behavior of functionally graded magneto-electro-thermo-elastic (FG-METE) nanoshells under various physical fields. NSGT modeling of the nanoshell contains two size parameters, one related to nonlocal stress field and another related to strain gradients. It is considered that mechanical, thermal, electrical and magnetic loads are exerted to the nanoshell. Temperature field has uniform and linear variation in nanoshell thickness. According to a power-law function, piezo-magnetic, thermal and mechanical properties of the nanoshell are considered to be graded in thickness direction. Five coupled governing equations have been obtained by using Hamilton's principle and then solved implementing Galerkin's method. Influences of temperature field, electric voltage, magnetic potential, nonlocality, strain gradient parameter and FG material exponent on buckling loads of the FG-METE nanoshell have been studied in detail.

Study for Structural Stabilities at High Temperatures of Beams Built with TMC Fire Resistant Steels (TMC 건축용 내화강재 적용 단순 보부재의 고온 거동에 관한 기초 연구)

  • Kwon, In-Kyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2016.10a
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    • pp.60-61
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    • 2016
  • Performance has been developed in terms of structural strength. Especially, in a structural steels, it is regarded as a common design process that an yield stress of thicker plate than 40mm uses that of below 40mm in thickness. This can be done using TMCP(Thermo mechanical control process). In this study, the structural stabilities such as deflection, maximum load carrying capacity would be calculated in high temperatures.

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Comparison of the Properties of Poly(butylene terephthalate) Nanocomposite Fibers with Different Organoclays

  • Kim, Jeong-Cheol;Chang, Jin-Hae
    • Macromolecular Research
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    • v.15 no.5
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    • pp.449-458
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    • 2007
  • The aims of this study were to investigate the intercalation of polymer chains with organoclays and improve the thermo-mechanical properties of poly(butylene terephthalate) (PBT) hybrids by comparing PBT hybrids synthesized using two different organoclays. The organoclays; dodecyltriphenylphosphonium-montmorillonite ($C_{12}PPh-MMT$) and dodecyltriphenylphosphonium-mica ($C_{12}PPh-Mica$), were used to fabricate the PBT hybrid fibers. Variations in the properties of the hybrid fibers with the organoclays within the polymer matrix, as well as the draw ratio (DR), are discussed. The thermo-mechanical properties and morphologies of the PBT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, electron microscopy and mechanical tensile properties analysis. The nanostructures of the hybrid fibers were determined using both scanning and transmission electron microscopies, which showed some of the clay layers to be well dispersed within the matrix polymer, although some clustered or agglomerated particles were also detected. The thermal properties of the hybrid fibers were found to be better than those of the pure PBT fibers at a DR = 1. The tensile mechanical properties of the $C_{12}PPh-MMT$ hybrid fibers were found to worsen with increasing DR. However, the initial moduli of the $C_{12}PPh-Mica$ hybrid fibers were found to slightly increase on increasing the DR from 1 to 18.

저합금강판의 열간프레스성형에 따른 상변태 전산 해석

  • Bok, Hyeon-Ho;Kim, Hun-Dong
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2010.05a
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    • pp.39.2-39.2
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    • 2010
  • Recently, hot stamping process has been paid attention greatly by automobile makers in accordance with the fuel efficiency and environmental issues as well as crash safety issue. The hot-stamped parts, however, demand extreme mechanical properties such as tensile strength of over 1470 MPa or equivalently Vickers hardness of around 450. In this work, to meet the demand efficiently, a method to predict mechanical property of hot-stamped parts based on numerical phase transformation scheme has been proposed associated with the thermo-mechanical coupled finite element analysis. This work deals with various phase transformation equations and validates them to select appropriate model for 0.2C-0.1Si-1.4Mn-0.5Cr-0.01Mo-0.002B steel sheet. The authors show that an efficient method saving time and cost to develop hot-stamped automobile parts ensuring suitable mechanical properties such as Vickers hardness and strength.

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