Simulation of the Effect of Solar Radiation on Hardening and Hardened Concrete Wall

2010 ◽  
Vol 163-167 ◽  
pp. 1489-1494
Author(s):  
Dong Hui Huang ◽  
Sheng Xing Wu ◽  
Hai Tao Zhao
Keyword(s):  
Mathematical Model ◽  
Finite Element Method ◽  
Finite Element ◽  
Thermal Stress ◽  
Solar Radiation ◽  
Numerical Models ◽  
Concrete Structures ◽  
Heat Of Hydration ◽  
Hardened Concrete ◽  
Concrete Wall

The purpose of the present study is to assess the effect of solar radiation on the development of thermal stress in hardening and hardened concrete structures. A mathematical model for solar radiation is investigated. A finite element method program is developed for the temperature and thermal stress analysis including the heat of hydration, creep, shrinkage, and ambient temperature, especially the solar radiation. Meanwhile, the effect of solar radiation on the concrete wall during its service life is considered. The results obtained from the numerical models show that for the hardening concrete wall, solar radiation reduce the stress at the first 36 hours on surface and first 48 hours in the center of the wall, after that the stresses both on surface and in the center of the wall increases quickly; for the hardened concrete wall, solar radiation increase the stress in the center of the wall. This program is useful to estimate the stress development and the effect of the solar radiation on the hardening and hardened concrete structures.

Temperature Distribution and Thermal Stress Analysis of Ball-Tank Subjected to Solar Radiation

2005 ◽  
Vol 127 (2) ◽  
pp. 119-122 ◽  
Author(s):  
Vishnu Verma ◽  
A. K. Ghosh ◽  
H. S. Kushwaha
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Thermal Stress ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Ambient Temperature ◽  
Research Reactor ◽  
The Finite Element Method ◽  
Large Structure ◽  
Seasonal And Diurnal Variation

The ball tank of the research reactor CIRUS is exposed to solar radiation. The ambient temperature undergoes seasonal and diurnal variation. The resulting thermal stress could be significant for the large structure. The temperature distribution has been obtained by the finite element method. The paper presents temperature distribution and the resulting thermal stress.

scholarly journals A 1D Model for Predicting Heat and Moisture Transfer through a Hemp-Concrete Wall Using the Finite-Element Method

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6903
Author(s):  
Maroua Benkhaled ◽  
Salah-Eddine Ouldboukhitine ◽  
Amer Bakkour ◽  
Sofiane Amziane
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Moisture Transfer ◽  
Construction Material ◽  
Climatic Conditions ◽  
Vapor Permeability ◽  
Transfer Model ◽  
The Finite Element Method ◽  
Concrete Wall ◽  
Element Method

Plant-based concrete is a construction material which, in addition to having a very low environmental impact, exhibits excellent hygrothermal comfort properties. It is a material which is, as yet, relatively unknown to engineers in the field. Therefore, an important step is to implement reliable mass-transfer simulation methods. This will make the material easy to model, and facilitate project design to deliver suitable climatic conditions. In recent decades, numerous studies have been carried out to develop models of the coupled transfers of heat, air and moisture in porous building envelopes. Most previous models are based on Luikov’s theory, considering mass accumulation, air and total pressure gradient. This theory considers the porous medium to be homogeneous, and therefore allows for hygrothermal transfer equations on the basis of the fundamental principles of thermodynamics. This study presents a methodology for solving the classical 1D (one-dimensional) HAM (heat, air, and moisture) hygrothermal transfer model with an implementation in MATLAB. The resolution uses a discretization of the problem according to the finite-element method. The detailed solution has been tested on a plant-based concrete. The energy and mass balances are expressed using measurable transfer quantities (temperature, water content, vapor pressure, etc.) and coefficients expressly related to the macroscopic properties of the plant-based concrete (thermal conductivity, specific heat, water vapor permeability, etc.), determined experimentally. To ensure this approach is effective, the methodology is validated on a test case. The results show that the methodology is robust in handling a rationalization of the model whose parameters are not ranked and not studied by their degree of importance.

Model calculations in reconstructions of measured fields

Open Physics ◽  
2003 ◽  
Vol 1 (1) ◽  
Author(s):  
Mihály Makai ◽  
Yuri Orechwa
Keyword(s):  
Mathematical Model ◽  
Finite Element Method ◽  
Finite Element ◽  
Group Theory ◽  
Point Group ◽  
Iterative Solution ◽  
The Finite Element Method ◽  
Technological Systems ◽  
Convergence Problem ◽  
Model Calculations

AbstractThe state of technological systems, such as reactions in a confined volume, are usually monitored with sensors within as well as outside the volume. To achieve the level of precision required by regulators, these data often need to be supplemented with the solution to a mathematical model of the process. The present work addresses an observed, and until now unexplained, convergence problem in the iterative solution in the application of the finite element method to boundary value problems. We use point group theory to clarify the cause of the non-convergence, and give rule problems. We use the appropriate and consistent orders of approximation on the boundary and within the volume so as to avoid non-convergence.

scholarly journals Parallel Finite Element Model for Multispecies Transport in Nonsaturated Concrete Structures

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2764 ◽  
Author(s):  
Okpin Na ◽  
Yunping Xi
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Model Prediction ◽  
Concrete Structures ◽  
Ionic Transport ◽  
Ionic Species ◽  
Chloride Ions ◽  
Moisture Movement ◽  
Parallel Finite Element ◽  
Saturated Concrete

The chloride-induced corrosion of steel reinforcement embedded in concrete is undoubtedly one of the most important durability problems of reinforced concrete structures. The chloride ions as well as other ionic species (Na+, Ca2+, K+, OH−) come from various deicing salts and they are transported from the environment into concrete. To investigate the transport mechanism of the multispecies, complex scientific methods and accurate mathematical models are needed. The purpose of this study is to develop a more robust mathematical model and better computational technique to characterize the coupled effect of ionic transport mechanisms as well as the influence of interaction of ionic species. The new mathematical model was developed based on the Nernst–Planck equation and null current condition to solve the ionic-induced electrostatic potential, and the model was implemented by a parallel finite element algorithm. The verification of mathematical model was done by comparing the model prediction with experimental results for ionic transport in saturated concrete. The comparisons showed good results. The model prediction of the multispecies transport in partially saturated concrete demonstrated that the ionic species dissolved in pore solution could be carried by the moisture movement and pressure gradient. Therefore, the multispecies transport model based on the parallel finite element method is effective, accurate, and can be used for solving the partial differential equations for ionic species transport in concrete.

Numerical Study on Electric Characteristics and Thermal Stresses of Solid Oxide Fuel Cells

2012 ◽  
Author(s):  
Pengfei Fan ◽  
Xiongwen Zhang ◽  
Guojun Li
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Thermal Stress ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Temperature Profile ◽  
Potential Distribution ◽  
Electrical Potential ◽  
Solid Oxide ◽  
Oxide Fuel

A generalized, three-dimensional (3D) mathematical model of solid oxide fuel cells (SOFCs) for various geometries is constructed in this paper. A finite-volume method is applied to calculate the electric characteristics, which is based on the fundamental conservation law of mass, energy and electrical charge. The electrical potential distribution, the current density distribution, the concentrations distribution of the chemical species and the temperature profile are calculated by solving the governing equations of a single-unit model with double channels of co-flow and counter-flow pattern using the commercial computational fluid dynamic software Fluent. The internal steam reforming and the water shift reactions are taken into account in the mathematical model. The Knudsen diffusion is considered for computation of the gases diffusion in the porous electrodes and the concentration overpotential. The Butler-Volmer equation and the function of the reaction gases composition for the exchange density are used in the model to analyze the activation overpotential. Numerical simulations are performed for a planar geometry solid oxide fuel cell and the detailed features of the temperature, the electrical potential distribution and the gases composition are illustrated. The simulation results agree well with the Benchmark results for planar configuration. With the simulated temperature profile in the planar SOFC, the finite-element method is employed to calculate the thermal stress distribution in the planar solid oxide fuel cell. A 3D finite-element model consists of positive electrode-electrolyte-negative electrode (PEN) and interconnects assembly is constructed by using commercial finite-element code Abaqus. The effects of temperature profile, electrodes and electrolyte thickness, and coefficients of thermal expansion (CTE) mismatch between components are characterized. The calculated results indicate that the maximum stress appears on the electrode and electrolyte interface. The value and distribution of the thermal stress are the functions of the applied materials CTE, applied temperature profiles and the thicknesses of electrode and electrolyte. The calculated results can be applied as the guide for the SOFC materials selection and the SOFC structure design.

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