• Title/Summary/Keyword: thermo-elastic

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A machine learning-based model for the estimation of the critical thermo-electrical responses of the sandwich structure with magneto-electro-elastic face sheet

  • Zhou, Xiao;Wang, Pinyi;Al-Dhaifallah, Mujahed;Rawa, Muhyaddin;Khadimallah, Mohamed Amine
    • Advances in nano research
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    • v.12 no.1
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    • pp.81-99
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    • 2022
  • The aim of current work is to evaluate thermo-electrical characteristics of graphene nanoplatelets Reinforced Composite (GNPRC) coupled with magneto-electro-elastic (MEE) face sheet. In this regard, a cylindrical smart nanocomposite made of GNPRC with an external MEE layer is considered. The bonding between the layers are assumed to be perfect. Because of the layer nature of the structure, the material characteristics of the whole structure is regarded as graded. Both mechanical and thermal boundary conditions are applied to this structure. The main objective of this work is to determine critical temperature and critical voltage as a function of thermal condition, support type, GNP weight fraction, and MEE thickness. The governing equation of the multilayer nanocomposites cylindrical shell is derived. The generalized differential quadrature method (GDQM) is employed to numerically solve the differential equations. This method is integrated with Deep Learning Network (DNN) with ADADELTA optimizer to determine the critical conditions of the current sandwich structure. This the first time that effects of several conditions including surrounding temperature, MEE layer thickness, and pattern of the layers of the GNPRC is investigated on two main parameters critical temperature and critical voltage of the nanostructure. Furthermore, Maxwell equation is derived for modeling of the MEE. The outcome reveals that MEE layer, temperature change, GNP weight function, and GNP distribution patterns GNP weight function have significant influence on the critical temperature and voltage of cylindrical shell made from GNP nanocomposites core with MEE face sheet on outer of the shell.

Shape Design Optimization of Ship Structures Considering Thermal Deformation and Target Shape (열 변형과 목적형상을 고려한 선체구조의 형상 최적설계)

  • Park, Sung-Ho;Choi, Jae-Yeon;Kim, Min-Geun;Cho, Seon-Ho
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.3
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    • pp.430-437
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    • 2010
  • In this paper, we develop a shape design optimization method for thermo-elastoplasticity problems that is applicable to the welding or thermal deformation problems of ship structures. Shell elements and a programming language APDL in a commercial finite element analysis code, ANSYS, are employed in the shape optimization. The point of developed method is to determine the design parameters such that the deformed shape after welding fits very well to a desired design. The geometric parameters of surfaces are selected as the design parameters. The modified method of feasible direction (MMFD) and finite difference sensitivity are used for the optimization algorithm. Two numerical examples demonstrate that the developed shape design method is applicable to existing hull structures and effective for the structural design of ships.

Topology Design Optimization of Nonlinear Thermo-elastic Structures (비선형 열탄성 연성구조의 위상 최적설계)

  • Moon, Min-Yeong;Jang, Hong-Lae;Kim, Min-Geun;Cho, Seon-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.5
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    • pp.535-541
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    • 2010
  • In this paper, we have derived a continuum-based adjoint design sensitivity of general performance functionals with respect to Young' modulus and heat conduction coefficient for steady-state nonlinear thermoelastic problems. An adjoint equation for temperature and displacement fields is defined for the efficient computation of the coupled field design sensitivity. Through numerical examples, we investigated the mesh dependency of the topology optimization method in the thermoelastic problems. Also, comparing the dominant loading cases of thermal and mechanical ones, the loading dependency of topology design optimization in coupled multi-physics problems is investigated.

The Analysis of Welding Deformation in Large Welded Structure by Using Local & Global Model (Local & Global 모델을 이용한 용접구조물 변형 해석에 관한 연구)

  • Jang Kyoung-Bok;Cho Si-Hoon;Jang Tae-Won
    • Journal of Welding and Joining
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    • v.22 no.6
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    • pp.25-29
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    • 2004
  • Some industrial steel structures are composed by components linked by several welding joints to constitute an assembly. The main interest of assembly simulation is to evaluate the global distortion of welded structure. The general method, thermo-elasto-plastic analysis, leads to excessive model size and computation time. In this study, a simplified method called "Local and Global approach" was developed to break down this limit and to provide a accurate solution for distortion. Local and global approach is composed of 3 steps; 1) Local simulation of each welding joint on a dedicated mesh (usually very fine due to high thermal gradients), taking into account for the non linearity of the material properties and the moving heat source. 2) Transfer to the global model of the effects of the welding joints by projection of the plastic strain tensors. 3) Elastic simulation to determine final distortions in global model. The welding deformation test for mock-up structure was performed to verify this approach. The predicted welding distortion by this approach had a good agreement with experiment results.

Effect of Mechanical Properties by a Long Term Operation in High Capacity and Low Sag Conductor ( II ) (경년열화가 증용량 저이도 송전선의 기계적특성에 미치는 영향 (II))

  • Kim Shang-Shu;Kim Byung-Geol;Sin Goo-Yong;Lee Dong-Il;Min Byung-Uk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.1
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    • pp.100-106
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    • 2006
  • Today, restricted energy sources, environmental considerations and the high cost of transporting fuel have limited the number and location of available power plant sites. The pressures resulting from these conditions have tended to require the construction of long, high-capacity, high-voltage power lines. it's used to adapt to STACIR/AW(Super Thermal-resistant Aluminum alloy Conductors, aluminum-clad Invar-Reinforced) conductor for coping with these situations. STACIR/AW conductor was formed by the combination of INVAR/AW as the core for low sag and super thermal-resistant aluminum alloy conductor for current capacity increase. increase of temperature by current capacity and long span lines make the susceptible to the deterioration of thermo-mechanical properties(conductivity, tensile strength, E-modulus and twist property et al). In the present work, changes of thermo-mechanical properties with aging have been studied in STACIR/AW $410 mm^2$ conductor with forms of single wire and strand wire.

A Study on the Thermo-mechanical Behavior of Underground Openings in lsotropic and Structurally Snisotropic Rock Masses (등방 및 이방성 암반내 공동의 열역학적 거동에 관한 전산모델연구)

  • 문현구;주광수
    • Tunnel and Underground Space
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    • v.1 no.2
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    • pp.181-203
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    • 1991
  • The effects of geologic structures such as rock joins and bedding planes on the thermal conductivity of a discontinuous rock mass are studied. The expressions for the equivalent thermal conductivities of jointed rock masses are derived and found to be anisotropic. The degree of anisotropy depends primarily on the thermal properties contrast between the joint phase and surrounding intact rock, the joint density expressed as volume fraction and the inclination angle of the joint. Within the context of 2-dimensional finite element heat transfer scheme, the isotherms around a circular hole are analyzed for both the isotropic and anisotropic rock masses in 3 different thermal boundary conditions. i.e. temperature, heat flux and convection boundary conditions. The temperature in the stratified anisotripic rock mass is greatly influenced by the thermal properties of the rock formation in contact with the heat source. Using the excavation-temperature coupled elastic plastic finite element method, analyzed is the thermo-mechanical stability of a circular opening subjected to 10$0^{\circ}C$ at a depth of 527m. It is found that the thermal stress concentration was enough to deteriorate the stability and form a plastic yield zone around the opening, in contrast to the safety factor greater than 2 resulted form the excavation-only analysis.

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Optimization dynamic responses of laminated multiphase shell in thermo-electro-mechanical conditions

  • Fan, Linyuan;Kong, Degang;Song, Jun;Moradi, Zohre;Safa, Maryam;Khadimallah, Mohamed Amine
    • Advances in nano research
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    • v.13 no.1
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    • pp.29-45
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    • 2022
  • The optimization for dynamic response associated with a cylindrical shell which is made of laminated composites embedded in a piezoelectric layer which is subjected to temperature rises and is resting on an elastic foundation is investigated for the first time. The first shear order theory (FSDT) is utilized in order to obtain the strain relations of the shell. Then, using the energy method, the equations of motions as well as boundary condition of the problem are attained. The formulation of this study together with the solution procedure which is a numerical solution method, differential quadrature method (DQM) is validated using other researches. This paper presents a thorough study on the parameters which impacts the vibration frequency of the laminated shell. The results of this paper shows that any type of laminated composite shell can reduce the vibration frequency providing that the angle related to layer are higher than 85 degrees. Also, in order to reduce the effect of temperature rises, the laminated composites instead of orthotropic one can be used.

Dynamic analysis of functionally graded (FG) nonlocal strain gradient nanobeams under thermo-magnetic fields and moving load

  • Alazwari, Mashhour A.;Esen, Ismail;Abdelrahman, Alaa A.;Abdraboh, Azza M.;Eltaher, Mohamed A.
    • Advances in nano research
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    • v.12 no.3
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    • pp.231-251
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    • 2022
  • Dynamic behavior of temperature-dependent Reddy functionally graded (RFG) nanobeam subjected to thermomagnetic effects under the action of moving point load is carried out in the present work. Both symmetric and sigmoid functionally graded material distributions throughout the beam thickness are considered. To consider the significance of strain-stress gradient field, a material length scale parameter (LSP) is introduced while the significance of nonlocal elastic stress field is considered by introducing a nonlocal parameter (NP). In the framework of the nonlocal strain gradient theory (NSGT), the dynamic equations of motion are derived through Hamilton's principle. Navier approach is employed to solve the resulting equations of motion of the functionally graded (FG) nanoscale beam. The developed model is verified and compared with the available previous results and good agreement is observed. Effects of through-thickness variation of FG material distribution, beam aspect ratio, temperature variation, and magnetic field as well as the size-dependent parameters on the dynamic behavior are investigated. Introduction of the magnetic effect creates a hardening effect; therefore, higher values of natural frequencies are obtained while smaller values of the transverse deflections are produced. The obtained results can be useful as reference solutions for future dynamic and control analysis of FG nanobeams reinforced nanocomposites under thermomagnetic effects.

Hygrothermal sound radiation analysis of layered composite plate using HFEM-IBEM micromechanical model and experimental validation

  • Binita Dash;Trupti R Mahapatra;Punyapriya Mishra;Debadutta Mishra
    • Structural Engineering and Mechanics
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    • v.89 no.3
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    • pp.265-281
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    • 2024
  • The sound radiation responses of multi-layer composite plates subjected to harmonic mechanical excitation in hygrothermal environment is numerically investigated. A homogenized micromechanical finite element (FE) based on the higher-order mid-plane kinematics replicating quadratic function as well as the through the thickness stretching effect together with the indirect boundary element (IBE) scheme has been first time employed. The isoparametric Lagrangian element (ten degrees of freedom per node) is used for discretization to attain the hygro-thermo-elastic natural frequencies and the modes of the plate via Hamilton's principle. The effective material properties under combined hygrothermal loading are considered via a micromechanical model. An IBE method is then implemented to attain structure-surrounding coupling and the Helmholtz wave equation is solved to compute the sound radiation responses. The effectiveness of the model is tested by converging it with the similar analytical/numerical results as well as the experimentally acquired data. The present scheme is further hold out for solving diverse numerical illustrations. The results revealed the relevance of the current higher-order FE-IBE micromechanical model in realistic estimation of hygro-thermo-acoustic responses. The geometrical parameters, volume fraction of fiber, layup, and support conditions alongside the hygrothermal load is found to have significant influence on the vibroacoustic characteristics.

Evaluation of Structural Stability of Fire Resistant Steel Produced by Thermo-Mechanical Control Process at High Temperature (TMCP 내화강재의 고온 내력 평가 연구)

  • Kwon, In-Kyu
    • Fire Science and Engineering
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    • v.27 no.6
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    • pp.21-25
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    • 2013
  • Fire resistance steel, grading 490 MPa, had developed by using Thermo-mechanical control process (TMCP) and it has better performance at welding, seismic resistance than those of the ordinary structural steel, But the fire resistance performance is required to verify against the ordinary fire resistance, FR 490. Therefore this study was done to make database of mechanical properties at high temperature and to evaluate the structural stability at high temperature in terms of materials and structural member such as H-section from that of FR 490. The result of this study was that the structural stability of TMCP was lower than that of ordinary FR 490 at the range up about $700^{\circ}C$.