Mathematical Modelling of Materials Behavior Under Creep Conditions

2001 ◽  
Vol 54 (2) ◽  
pp. 107-132 ◽  
Author(s):  
J. Betten
Keyword(s):  
Experimental Data ◽  
Mathematical Modelling ◽  
Mechanical Behavior ◽  
Review Article ◽  
Material Behavior ◽  
Experimental Investigations ◽  
Rational Basis ◽  
Complex Material ◽  
Interpolation Methods ◽  
Materials Behavior

This article will provide a short survey of some recent advances in the mathematical modelling of materials behavior under creep conditions. The mechanical behavior of anisotropic solids requires a suitable mathematical modelling. The properties of tensor functions with several argument tensors constitute a rational basis for a consistent mathematical modelling of complex material behavior. This article presents certain principles, methods, and recent successful applications of tensor functions in creep mechanics. The rules for specifying irreducible sets of tensor invariants and tensor generators for material tensors of rank two and four are also discussed. Furthermore, it is very important that the scalar coefficients in constitutive and evolutional equations are determined as functions of the integrity basis and experimental data. It is explained in detail that these coefficients can be determined by using tensorial interpolation methods. Some examples for practical use are discussed. Finally, we have carried out our own experiments to examine the validity of the mathematical modelling. Furthermore, an overview of some important experimental investigations in creep mechanics of other scientists has been provided. There are 243 references cited in this review article.

Thermo-Hydro-Mechanical Simulation of a Heating and Hydration Experimental Study (the China-Mock-Up) in GMZ Bentonite

2011 ◽  
Author(s):  
L. Chen ◽  
J. Wang ◽  
Y. M. Liu ◽  
F. Collin ◽  
J. L. Xie
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Qualitative Analysis ◽  
Mechanical Behavior ◽  
Liquid Water ◽  
Numerical Study ◽  
Experimental Investigations ◽  
Gmz Bentonite ◽  
Present Stage ◽  
Proposed Model

This paper presents a numerical study of the China-Mock-up test, with the purpose of evaluating the performance of Gaomiaozi (GMZ) bentonite under coupled thermo-hydro-mechanical (THM) conditions. In the paper, the basic THM characteristics of GMZ bentonite are presented first. The formulation of coupling heat, moisture (liquid water and water vapour) and air transfer is given. The model of Alonso-Gens (1) is incorporated to reproduce the mechanical behavior of the GMZ bentonite under unsaturated conditions. With the parameters determined from experimental investigations, numerical simulations of the China-Mock-up test are carried out using the code of LAGAMINE. Owing to the lack of experimental data at present stage, a qualitative analysis of the predictive results is realized. The results suggest that the proposed model is able to reproduce the mechanical behavior of GMZ bentonite, and to predict moisture and air motions under thermal solicitations.

scholarly journals Phase Relations in the ZrO2-MgO-FeOx System: Experimental Data and Assessment of Thermodynamic Parameters

2021 ◽  
Author(s):  
Ivan Saenko ◽  
O. Fabrichnaya
Keyword(s):  
Electron Microscopy ◽  
Experimental Data ◽  
Solid Solution ◽  
Thermodynamic Parameters ◽  
Spinel Phase ◽  
Experimental Investigations ◽  
X Ray ◽  
Heat Treated ◽  
Preliminary Phase ◽  
Scanning Electron

AbstractThermodynamic parameters were assessed for the MgO–FeOx system and combined with already available descriptions of ZrO2-FeOx and ZrO2-MgO systems to calculate preliminary phase diagrams for planning experimental investigations. Samples of selected compositions were heat treated at 1523, 1673 and 1873 K and characterized using x-ray and scanning electron microscopy combined with energy dispersive x-ray spectroscopy (SEM/EDX). Experiments indicated extension of cubic ZrO2 solid solution into the ternary system at 1873 K (75 mol.% ZrO2, 10 mol.% FeOx and 15 mol.% MgO) and limited solubility of 4 mol.% ZrO2 in spinel phase. Based on the obtained results thermodynamic parameters of C-ZrO2 and spinel phase were optimized.

scholarly journals Validation of MATLAB algorithm to implement a two-step parallel pyrolysis model for the prediction of maximum %char yield

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Ibiba Taiwo Horsfall ◽  
Macmanus Chinenye Ndukwu ◽  
Fidelis Ibiang Abam ◽  
Ololade Moses Olatunji ◽  
Ojong Elias Ojong ◽  
...  
Keyword(s):  
Experimental Data ◽  
Isothermal Condition ◽  
Char Yield ◽  
Experimental Investigations ◽  
Time Saving ◽  
Pyrolysis Products ◽  
Pyrolysis Model ◽  
Experimental Yield ◽  
By Products ◽  
Good Agreement

AbstractNumerical modeling of biomass pyrolysis is becoming a cost and time-saving alternative for experimental investigations, also to predict the yield of the by-products of the entire process. In the present study, a two-step parallel kinetic model was used to predict char yield under isothermal condition. MATLAB ODE45 function codes were employed to solve a set of differential equations that predicts the %char at varying residence times and temperatures. The code shows how the various kinetic parameters and mass of pyrolysis products were determined. Nevertheless, the algorithm used for the prediction was validated with experimental data and results from past works. At 673.15 K, the numerical simulation using ODE45 function gives a char yield of 27.84%. From 573.15 K to 673.15 K, char yield ranges from 31.7 to 33.72% to 27.84% while experimental yield decreases from 44 to 22%. Hence, the error between algorithm prediction and experimental data from literature is − 0.26 and 0.22. Again, comparing the result of the present work with the analytical method from the literature showed a good agreement.

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

2017 ◽  
Author(s):  
Stefan Schmid ◽  
Rudi Kulenovic ◽  
Eckart Laurien
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Test Rig ◽  
Reduced Pressure ◽  
Flow Rates ◽  
Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

Experimental Methodologies: Two Case Studies Investigating the Syntax- Discourse Interface

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
Timothy Gupton ◽  
Tania Leal Méndez
Keyword(s):  
Experimental Data ◽  
Quantitative Data ◽  
Native Speaker ◽  
Experimental Methods ◽  
Experimental Investigations ◽  
Experimenter Bias ◽  
Current Article ◽  
Theoretical Syntax ◽  
Discourse Interface ◽  
L1 And L2

AbstractThe current article examines two experimental investigations of the syntaxdiscourse interface, which address theoretical questions in different ways: the first is an L1 investigation of Galician speakers in Gupton (2010) and the second is a dual investigation of L1 and L2 Spanish reported on in Leal Méndez & Slabakova (2011). These investigations gathered quantitative data via psycholinguistic tasks with accompanying audio utilizing the WebSurveyor platform. They involved counterbalanced designs and were followed by statistical analysis. While acknowledging that experimental data does not have primacy over intuitive data, the authors endorse the use of experimental methods of data elicitation (such as the ones already used in generative SLA research) in theoretical syntax in order to avoid experimenter bias and to get a more complete picture of native speaker intuition and competencies.

Constitutive modeling for the mechanical behavior of rubber with filler particles

2021 ◽  
Author(s):  
Sankalp Gour ◽  
Deepu Kumar Singh ◽  
Deepak Kumar ◽  
Vinod Yadav
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Mechanical Behavior ◽  
Experimental Observation ◽  
Continuum Mechanics ◽  
Constitutive Modeling ◽  
Carbon Nanoparticles ◽  
Material Behavior ◽  
Experimental Results ◽  
Filler Particles

Abstract The present study deals with the constitutive modeling for the mechanical behavior of rubber with filler particles. An analytical model is developed to predict the mechanical properties of rubber with added filler particles based on experimental observation. To develop the same, a continuum mechanics-based hyperelasticity theory is utilized. The model is validated with the experimental results of the chloroprene and nitrile butadiene rubbers filled with different volume fractions of carbon black and carbon nanoparticles, respectively. The findings of the model agree well with the experimental results. In general, the developed model will be helpful to the materialist community working in characterizing the material behavior of tires and other rubber-like materials.

scholarly journals DECIPHERING THE FINEST IMPRINT OF GLACIAL EROSION: OBJECTIVE ANALYSIS OF STRIAE PATTERNS ON BEDROCK

2011 ◽  
Vol 23 (3) ◽  
pp. 135 ◽  
Author(s):  
Piet Stroeven ◽  
Arjen Peter Stroeven ◽  
Jing Hu ◽  
Jean-Louis Chermant ◽  
Michel Coster
Keyword(s):  
Experimental Data ◽  
Image Analysis ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Orientation Distribution ◽  
Experimental Investigations ◽  
Automatic Image Analysis ◽  
Glacial Erosion ◽  
Analysis Techniques ◽  
Image Analysis Techniques

The aim of this study is to compare the efficiency of different mathematical and statistical geometrical methods applied to characterise the orientation distribution of striae on bedrock for deciphering the finest imprint of glacial erosion. The involved methods include automatic image analysis techniques of Fast Fourier Transform (FFT), and the experimental investigations by means of Saltikov's directed secants analysis (rose of intersection densities), applied to digital and analogue images of the striae pattern, respectively. In addition, the experimental data were compared with the modelling results made on the basis of Underwood's concept of linear systems in a plane. The experimental and modelling approaches in the framework of stereology yield consistent results. These results reveal that stereological methods allow a reliable and efficient delineation of different families of glacial striae from a complex record imprinted in bedrock.

scholarly journals Theoretical and Experimental Investigations on Transient Run-Up Procedures of Journal Bearings Including Mixed Friction Conditions

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 105 ◽  
Author(s):  
Maximilian Prölß ◽  
Hubert Schwarze ◽  
Thomas Hagemann ◽  
Philipp Zemella ◽  
Philipp Winking
Keyword(s):  
Experimental Data ◽  
Energy Equation ◽  
Hydrodynamic Lubrication ◽  
Frictional Coefficient ◽  
Journal Bearings ◽  
Numerical Code ◽  
Experimental Investigations ◽  
Lubrication Regime ◽  
Mixed Friction ◽  
Run Up

This paper focuses on the operating behavior of journal bearings for industrial machinery application during run-ups. For this purpose, a numerical simulation code that is based on a two-dimensional extended and generalized Reynolds equation and a full three-dimensional energy equation, was advanced by a theoretical model considering the effects of mixed friction and warming of journal components during start-up. The mixed friction routine contained the elastic half-spaces model proposed by Boussinesq, which considers the influence of rough surfaces by implementing flow factors and calculates additional stiffness and dissipation in areas with solid interactions. Furthermore, a transient term was added in the energy equation to consider the thermal inertia of journal, and bearing to ensure a realistic heating during run-ups. Results of the prediction were compared to experimental data taken from a special test rig built up for validation procedures. Besides the conventional sensors for temperature, oil flow, and relative motion between shaft and stator, a contact voltage measurement was installed to determine the intensity of mixed friction. The evaluation of experimental data by Stribeck curves, based on a shaft torsion measurement, indicated a significant influence of run-up time on frictional moment. The friction coefficient of the rotor bearing system was strongly influenced by the run-up time. A short run-up time reduced the frictional coefficient in the mixed lubrication regime while the opposite behavior was observed in the hydrodynamic lubrication regime. The numerical code predicted these tendencies in good agreement with experimental data, however, only if the transient energy model was applied.

Implosion Analysis of Concrete Cylindrical Vessels

1979 ◽  
Vol 101 (1) ◽  
pp. 98-102
Author(s):  
H. Suzuki ◽  
W. F. Chen ◽  
T. Y. Chang
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Fracture Behavior ◽  
Constitutive Relations ◽  
Analysis Procedure ◽  
Material Behavior ◽  
Ultimate State ◽  
Element Analysis ◽  
Proposed Model ◽  
Effect Of Hydrostatic Pressure

Concrete constitutive relations which can simulate the overall material behavior up to and including its ultimate state under general triaxial loading conditions have been developed. The proposed constitutive relations include: 1) plastic deformation considering the effect of hydrostatic pressure, 2) a dual criterion predicting the fracture of concrete in terms of either stresses or strains, and 3) post-fracture behavior of concrete. Corresponding to the constitutive model, a finite element analysis procedure has also been utilized. Based on the proposed model, implosion pressures and load-deformation responses of several concrete vessels were obtained. The numerical results correlate quite well with the experimental data when the dual criterion was used.

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