Boundary Conditions for Thermal Load on Concrete Structures

2021 ◽  
pp. 405-421
Author(s):  
Victor E. Saouma ◽  
M. Amin Hariri-Ardebili
Keyword(s):  
Boundary Conditions ◽  
Thermal Load ◽  
Concrete Structures

Numerical Analysis of Effect of Cyclic Thermal Load on Concrete to Concrete Bonding

2016 ◽  
Vol 722 ◽  
pp. 18-26 ◽  
Author(s):  
Yuliia Khmurovska ◽  
Petr Štemberk ◽  
Martin Petřík ◽  
Ippei Maruyama ◽  
Ondřej Holčapek
Keyword(s):  
Experimental Investigation ◽  
Thermal Load ◽  
Thermal Loading ◽  
Concrete Structures ◽  
High Quality ◽  
Bonding Quality ◽  
Critical Stresses ◽  
First Results ◽  
Adhesive Materials

This paper presents a numerical simulation and preliminary experimental investigation of bonding of concrete structures using cement and polymer cement as adhesive materials. The numerical model of concrete plates bonded with the polymer cement is created and subjected to cyclic thermal loading. As a result, the critical stresses are obtained. Also all the necessary materials for carrying out high-quality, fast and inexpensive experimental investigation of the strength of cement and polymer cement bond are prepared. The experimental setup and the first results obtained are also described. The bonding quality of the polymer cement shows satisfactory results under this kind of loading, thus the use of the polymer cement for bonding of concrete structures of different properties is reasonable in the specific fields considered in this study.

scholarly journals Modeling and Thermal-Mechanical Coupling Analysis of Piston in Car Engines

2020 ◽  
Vol 45 (1) ◽  
pp. 83-92
Author(s):  
Feifei Zhao
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Stress Distribution ◽  
Stress Field ◽  
Boundary Conditions ◽  
Thermal Load ◽  
Mechanical Load ◽  
Field Analysis ◽  
Coupling Analysis ◽  
Mechanical Coupling

In this paper, finite-element analysis (FEA) is carried out on the temperature field and stress field of automobile engine piston, as well as the thermal-mechanical load coupling stress field. Through the analysis, the authors grasped the thermal load and combined stress distribution of the piston, and thus optimized the piston design to improve its operational reliability. Specifically, a 1/4 solid model of the piston was constructed in the three-dimensional (3D) computer-aided design (CAD) software Pro/ENGINEER, and then converted into a finite-element model in Pro/Mechanica. Then, an alternating load was imposed on the piston model, and fatigue analysis was performed to identify the parts of the piston prone to fatigue failure, and judge whether the piston structure satisfies working requirements. Next, temperature field analysis was carried out on the piston model. The distribution of the steady-state temperature field as determined by applying temperatures and heat transfer coefficients as required by the boundary conditions of the third kind. Finally, the piston model was subject to thermal-mechanical coupling analysis. The stress and deformation distributions of the piston under the coupled stress field were ascertained under the boundary conditions of temperature field distribution and mechanical load. Through the above work, the authors obtained the basis for safety evaluation of piston, laying the foundation for further reducing the thermal load and optimizing the stress distribution of piston.

scholarly journals On the boundary conditions formulation in the problems of synthesis of woven 3d materials

2021 ◽  
pp. 114-121
Author(s):  
Евгений Валерьевич Мурашкин
Keyword(s):  
Boundary Conditions ◽  
Boundary Value Problems ◽  
Stress Tensor ◽  
Constitutive Relations ◽  
Boundary Value ◽  
Concrete Structures ◽  
Differential Constraints ◽  
Complete Formulation

В статье обсуждаются формулировки определяющих дифференциальных ограничений на поверхности наращивания на случай моделирования процессов формирования 3D материала, характеризующегося дополнительными характерными директорами (направлениями выкладки волокон в тканых материалах, арматуры в бетонных конструкциях). Выведена общая форма тензорного соотношения на поверхности наращивания, при учете дополнительных выделенных направлений. Определить набор совместных рациональных инвариантов тензора напряжений и характерных директоров. Дана инвариантно-полная формулировка определяющих соотношений на поверхности наращивания. Полученные результаты могут быть использованы для постановки и решения краевых задач, моделирующих процессы синтеза тканых 3D материалов. The article discusses the formulation of the defining differential constraints on the buildup surface in the case of modeling the processes of forming a 3D material characterized by additional characteristic directors (directions of laying fibers in woven materials, reinforcement in concrete structures). The general form of the tensor relation on the growing surface is derived, taking into account the additional selected directions. Determine the set of joint rational invariants of the stress tensor and characteristic directors. An invariant-complete formulation of the constitutive relations on the surface of the build-up is given. The results obtained can be used to formulate and solve boundary value problems that simulate the processes of synthesis of woven 3D materials.

Hot-streak effect on internally air-cooled nozzle guide vanes and shrouds

2019 ◽  
Vol 123 (1270) ◽  
pp. 2019-2033
Author(s):  
L. Y. Jiang ◽  
Y. Han ◽  
Z. Zhang ◽  
X. Wu ◽  
M. Clement ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Thermal Load ◽  
Physical Models ◽  
Maximum Temperature ◽  
Second Step ◽  
High Fidelity ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Nozzle Guide Vanes

ABSTRACTThe effect of hot streaks from a gas turbine combustor on the thermodynamic load of internally air-cooled nozzle guide vanes (NGVs) and shrouds has been numerically investigated under flight conditions. The study follows two steps: one for the high-fidelity 60° combustor sector with simplified ten NGVs and three thermocouples attached; and the other for the NGV sectors where each sector consists of one high-fidelity NGV (probe NGV) and nine dummy NGVs. The first step identifies which NGV has the highest thermal load and provides the inlet flow boundary conditions for the second step. In the second step, the flow fields and thermal loads of the probe NGVs are resolved in detail.With the systematically validated physical models, the two-phase flowfield of the combustor-NGVs sector has been successfully simulated. The predicted mean and maximum temperature at the combustor sector exit are in excellent agreement with the experimental data, which provides a solid basis for the hot-streak effect investigation. The results indicate that the second NGV, looking upstream from left, has the highest thermal load. Its maximum surface temperature is 8.4% higher than that for the same NGV but with the mean inlet boundary conditions, and 14.1% higher than the ninth NGV. The finding is consistent with the field-observed NGV damage pattern. To extend the service life of these vulnerable NGVs, some protection methods should be considered.

scholarly journals Effects of temperature and temperature gradient on concrete performance at elevated temperatures

2017 ◽  
Vol 21 (8) ◽  
pp. 1223-1233 ◽  
Author(s):  
Quang X Le ◽  
Vinh TN Dao ◽  
Jose L Torero ◽  
Cristian Maluk ◽  
Luke Bisby
Keyword(s):  
Temperature Gradient ◽  
Boundary Conditions ◽  
Elevated Temperatures ◽  
Concrete Structures ◽  
Constitutive Models ◽  
Concrete Surface ◽  
Temperature Gradients ◽  
Image Correlation ◽  
Test Setup ◽  
Thermal Boundary Conditions

To assure adequate fire performance of concrete structures, appropriate knowledge of and models for performance of concrete at elevated temperatures are crucial yet currently lacking, prompting further research. This article first highlights the limitations of inconsistent thermal boundary conditions in conventional fire testing and of using constitutive models developed based on empirical data obtained through testing concrete under minimised temperature gradients in modelling of concrete structures with significant temperature gradients. On that basis, this article outlines key features of a new test setup using radiant panels to ensure well-defined and reproducible thermal and mechanical loadings on concrete specimens. The good repeatability, consistency and uniformity of the thermal boundary conditions are demonstrated using measurements of heat flux and in-depth temperature of test specimens. The initial collected data appear to indicate that the compressive strength and failure mode of test specimens are influenced by both temperature and temperature gradient. More research is thus required to further quantify such effect and also to effectively account for it in rational performance-based fire design and analysis of concrete structures. The new test setup reported in this article, which enables reliable thermal/mechanical loadings and deformation capturing of concrete surface at elevated temperatures using digital image correlation, would be highly beneficial for such further research.

The Large Scale In-Situ PRACLAY Heater and Seal Tests in URL HADES, Mol, Belgium

2013 ◽  
Author(s):  
Xiangling Li ◽  
Guangjing Chen ◽  
Jan Verstricht ◽  
Philippe Van Marcke ◽  
Ioannis Troullinos
Keyword(s):  
Boundary Conditions ◽  
Host Rock ◽  
Thermal Load ◽  
Total Pressure ◽  
Large Scale ◽  
Primary Objective ◽  
Geological Disposal ◽  
Boom Clay ◽  
Clay Formation

In Belgium, the URL HADES was constructed in the Boom Clay formation at the Mol site to investigate the feasibility of geological disposal in a clay formation. Since 1995, the URL R&D programme has focused on large scale demonstration tests like the PRACLAY Heater and Seal tests. The main objective of the Heater Test is to demonstrate that the thermal load generated by the heat-emitting waste will not jeopardise the safety functions of the host rock. The primary objective of the Seal Test is to provide suitable hydraulic boundary conditions for the Heater Test. The Seal Test also provides an opportunity to investigate the in-situ behaviour of a bentonite-based EBS. The PRACLAY gallery was constructed in 2007 and the hydraulic seal was installed in 2010. The bentonite is hydrated both naturally and artificially. The swelling, total pressure and pore pressure of the bentonite are continuously measured and analysed by numerical simulations to get a better understanding of this hydration processes. The timing of switching on the heater depends on the progress of the bentonite hydration, as a sufficient seal swelling is needed to fulfill its role. A set of conditions to be met for the heater switch-on and its schedule will be given.

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