scholarly journals An analytical method for calculating the stress-strain state of PVC window profiles under thermal loading

Vestnik MGSU ◽  
2021 ◽  
pp. 1437-1451
Author(s):  
Ivan S. Aksenov ◽  
Aleksandr P. Konstantinov
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Cross Sections ◽  
Thermal Loading ◽  
Solid Mechanics ◽  
Analytical Calculation ◽  
Temperature Fields ◽  
Structural Behavior ◽  
Starting Point ◽  
Temperature Deformations

Introduction. The practical operation of modern PVC windows in the climate of the Russian Federation has proven that due to thermally induced deformations of window elements cold air enters premises and window frames freeze. Presently, there is no engineering method for calculating the temperature deformations of windows, that takes account of the key features of their structure: the composite structure of window sections, the rigidity of insulating glass units, fittings, etc. An important task is to develop a method for calculating temperature deformations of PVC window elements, that takes account of nonlinear temperature distribution over their cross-sections. Materials and methods. A three-dimensional finite element model of a standard PVC window was developed using the COMSOL Multiphysics software, and its temperature field was calculated. The analysis of the calculation results allowed to identify the nature of the temperature distribution over the cross sections of PVC window profiles and propose a method for their analytical calculation. Using the basic equations of solid mechanics and methods of mathematical analysis, the bending of PVC window elements was described on the basis of their actual temperature fields. Results. The obtained equations were tested by comparing the results of the manual calculation with the results of the finite element modeling. Conclusions. The obtained equations, describing temperature deformations of individual window elements, serve as the starting point for an integrated method of calculating the structural behavior of PVC windows under thermal loading. The further development of the presented method will encompass the analysis of the influence of the reinforcing core on the structural behavior of PVC elements and the exploration of the structural behavior of the entire window structure.

scholarly journals Analysis of temperature-induced deformation and stress distribution of long-span concrete truss combination arch bridge based on bridge health monitoring data and finite element simulation

2020 ◽  
Vol 16 (10) ◽  
pp. 155014772094520
Author(s):  
Yanwei Niu ◽  
Yong’e Wang ◽  
Yingying Tang
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Stress Distribution ◽  
Health Monitoring ◽  
Three Dimensional ◽  
Monitoring Data ◽  
Temperature Fields ◽  
Structural Deformation ◽  
Arch Bridge ◽  
Bridge Health Monitoring

Through decades of operation, deformation fluctuation becomes a central problem affecting the normal operating of concrete truss combination arch bridge. In order to clarify the mechanism of temperature-induced deformation and its impact on structural stress distribution, this article reports on the temperature distribution and its effect on the deformation of concrete truss combination arch bridge based on bridge health monitoring on a proto bridge with 138 m main span. The temperature distribution and deformation characteristics of the bridge structure in deep valley area are studied. Both of the daily and yearly temperature variation and structural deformation are studied based on bridge health monitoring. Using the outcome of monitoring data, three-dimensional solid finite element models are established to analyze the mechanism of temperature-induced deformation of the whole bridge under different temperature fields. The influence of temperature-induced effect is discussed on local damage based on the damage observation of the background bridge. The outcome of comparisons with field observation validates the analysis results. The relevant monitoring and simulation result can be referenced for the design and evaluation of similar bridges.

The Airplane Hangars of Pier Luigi Nervi: Digital and Scaled Models

2020 ◽  
Vol 61 (3) ◽  
pp. 187-200
Author(s):  
Giulio M. Barazzetta ◽  
Emilio Mossa ◽  
Carlo Poggi ◽  
Marco Simoncelli
Keyword(s):  
Finite Element ◽  
Finite Element Methods ◽  
Structural Models ◽  
Structural Behavior ◽  
Complex Structures ◽  
The Past ◽  
Starting Point ◽  
Complete Study ◽  
Scaled Models ◽  
Work Done

The paper presents a complete study of the work done by Pier Luigi Nervi for the design and construction of a series of concrete hangars between 1935 and 1940. This research is enclosed in the framework of the exhibition entitled "Pier Luigi Nervi, il modello come strumento di progetto e costruzione" that gathers researches from Università degli Studi di Bologna, Università di Roma Tor Vergata and Politecnico di Milano. The exhibition was used as a starting point for a general discussion about the meaning of the logical passage that leads engineers and architects from physical scaled models to numerical structural models. The Politecnico di Milano contributed to re-writing the first experiences of Pier Luigi Nervi and Arturo Danusso in the structural modeling. Scaled models, nowadays substituted by finite element methods, were widely used in the past, for the understanding of the structural behavior of complex structures. Unfortunately, many of these masterpieces have been destroyed during the years (as happened to the two original models tested by Pier Luigi Nervi and reproduced for the exhibition). <br/> In the last part of the paper, based on numerical results, the structural behavior of these hangars is deeply discussed, underlining all the principal strengths and weaknesses of these complex structures.

Approximate Direct and Inverse Relationships for Thermal and Stress States in Thick-Walled Vessels Under Thermal Shock

2006 ◽  
Vol 129 (1) ◽  
pp. 52-57 ◽  
Author(s):  
A. E. Segall ◽  
R. Akarapu
Keyword(s):  
Finite Element ◽  
Thermal Shock ◽  
Thermal Loading ◽  
Thermoelastic Stress ◽  
Internal Surface ◽  
Approximate Solutions ◽  
Stress Distributions ◽  
Starting Point ◽  
Laplace Transformations ◽  
Stress States

Approximate solutions were derived for the transient through steady-state thermal-stress fields developed in thick-walled vessels subjected to a potentially arbitrary thermal shock. In order to accomplish this, Duhamel’s integral was first used to relate the arbitrary thermal loading to a previously derived unit kernel for tubular geometries. Approximate rules for direct and inverse Laplace transformations were then used to modify the resulting Volterra equation to an algebraically solvable and relatively simple form. The desired thermoelastic stress distributions were then determined using the calculated thermal states and elasticity theory. Good agreement was seen between the derived temperature and stress relationships and earlier analytical and finite-element studies of a cylinder subjected to an asymptotic exponential heating on the internal surface with convection to the outer environment. It was also demonstrated that the derived relationships can be used to approximate the more difficult inverse (deconvolution) thermal problem for both exponential (monotonic) and triangular (non-monotonic) load histories. The use of polynomial of powers tn∕2 demonstrated the feasibility of employing the method with empirical data that may not be easily represented by standard functions. For any of the direct and inverse cases explored, the resulting relationships can be used to verify, calibrate, and/or determine a starting point for finite-element or other numerical methods.

Buckling/Elastoplastic Collapse Behavior and Strength of Continuous Tee-Bar Stiffened Plates

2005 ◽  
Vol 128 (2) ◽  
pp. 145-155 ◽  
Author(s):  
Kenneth Sunil Mukherjee ◽  
Tetsuya Yao
Keyword(s):  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Cross Sections ◽  
Structural Behavior ◽  
Stiffened Plates ◽  
Plastic Collapse ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Collapse Behavior

The influence of residual stress distributions should be properly taken into account in the structural analysis of stiffened plates. The generally assumed residual stress distributions in the analyses often have constant values across their cross sections. This approximation is also applied to identical stiffeners that are constructed by different methods, such as rolled and built-up tee-bar stiffened plates. This paper focuses on buckling/plastic collapse behavior of rolled and built-up tee-bar stiffened plates with experimentally determined residual stress distributions in their cross sections. The structural behavior until collapse of these two types of tee-bar stiffeners is analyzed in detail, using residual stresses measured from experimental results. Various numerical modelling aspects of stiffened plated structures are briefly discussed and finally the influence of differences in residual stress distributions on buckling/plastic collapse behavior of continuous stiffened plates is studied based on selected results, using the Finite Element Method.

The Plastic Ratcheting of Thin Cylindrical Shells Subjected to Axisymmetric Thermal and Mechanical Loading

1987 ◽  
Vol 109 (4) ◽  
pp. 387-393 ◽  
Author(s):  
S. Karadeniz ◽  
A. R. S. Ponter ◽  
K. F. Carter
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Mechanical Loading ◽  
Material Properties ◽  
Thermal Loading ◽  
Cylindrical Shells ◽  
Temperature Fields ◽  
Mechanical Loads ◽  
Element Technique ◽  
The Relationship

The paper discusses the relationship between material properties and structural ratcheting for thin cylindrical shells subjected to severe thermal loading. The need to understand this problem arises in the design of Sodium Cooled Fast Reactors. A sequence of shakedown solutions are presented using a finite element technique [13]. It is shown that for tubes subject to moving temperature fields, ratcheting can occur even when no mechanical loads are applied and the material strongly cyclically hardens. Only small movements are required. Stationary thermal cycling is less likely to produce ratcheting. The calculations are compared with two sets of experimental data, which serve to confirm these conclusions.

Numerical Simulation of Temperature Field in Laser Remanufacturing

2014 ◽  
Vol 633-634 ◽  
pp. 845-849
Author(s):  
Ling Dong ◽  
Xi Chen Yang ◽  
Yun Shan Wang ◽  
Jian Bo Lei
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Temperature Field ◽  
Theoretical Model ◽  
Temperature Distribution ◽  
Simulation Method ◽  
Temperature Fields ◽  
Simulation Results

It plays an important role in guiding laser remanufacturing process and process control to research temperature field of laser remanufacturing. A numerical simulation method of temperature field based on MATLAB PDE Tool is proposed. Theoretical model of temperature field is presented. The temperature fields at different times are calculated and simulated with finite element method and MATLAB software with PDE Toolbox. The results show that this method can accurately calculate the temperature distribution of the laser remanufacturing process. The simulation results are helpful to optimize process parameters and to improve the quality of laser remanufacturing.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

scholarly journals Stator Non-Uniform Radial Ventilation Design Methodology for a 15 MW Turbo-Synchronous Generator Based on Single Ventilation Duct Subsystem

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2760
Author(s):  
Ruiye Li ◽  
Peng Cheng ◽  
Hai Lan ◽  
Weili Li ◽  
David Gerada ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Design Methodology ◽  
Large Scale ◽  
Synchronous Generator ◽  
Axial Direction ◽  
Scale Model ◽  
Element Analysis ◽  
Axial Temperature ◽  
Ventilation Duct

Within large turboalternators, the excessive local temperatures and spatially distributed temperature differences can accelerate the deterioration of electrical insulation as well as lead to deformation of components, which may cause major machine malfunctions. In order to homogenise the stator axial temperature distribution whilst reducing the maximum stator temperature, this paper presents a novel non-uniform radial ventilation ducts design methodology. To reduce the huge computational costs resulting from the large-scale model, the stator is decomposed into several single ventilation duct subsystems (SVDSs) along the axial direction, with each SVDS connected in series with the medium of the air gap flow rate. The calculation of electromagnetic and thermal performances within SVDS are completed by finite element method (FEM) and computational fluid dynamics (CFD), respectively. To improve the optimization efficiency, the radial basis function neural network (RBFNN) model is employed to approximate the finite element analysis, while the novel isometric sampling method (ISM) is designed to trade off the cost and accuracy of the process. It is found that the proposed methodology can provide optimal design schemes of SVDS with uniform axial temperature distribution, and the needed computation cost is markedly reduced. Finally, results based on a 15 MW turboalternator show that the peak temperature can be reduced by 7.3 ∘C (6.4%). The proposed methodology can be applied for the design and optimisation of electromagnetic-thermal coupling of other electrical machines with long axial dimensions.

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