scholarly journals Identification of moisture transport mechanism in gypsum during convective drying

2018 ◽  
Author(s):  
Robert Adamski ◽  
A. Adamska ◽  
Z. Pakowski
Keyword(s):  
Internal Pressure ◽  
Young’S Modulus ◽  
Moisture Transport ◽  
Transport Mechanism ◽  
Young's Modulus ◽  
Practical Importance ◽  
Sorption Isotherms ◽  
Convective Drying ◽  
Drying And Rewetting ◽  
Pressure Development

Gypsum is a popular building material. Drying and rewetting of gypsum is a process of practical importance. This work presents the experimental results of kinetic of drying, heating and internal pressure development in rewetted gypsum cylinders. Analysis of the observed changes is presented. Additionally sorption isotherms, permeability and dependence of Young’s modulus on moisture content were measured. These data will be used in the model of the process under development.   Keywords: internal pressure, permeability, Young’s modulus 

Effective properties of composite materials containing voids

1993 ◽  
Vol 440 (1909) ◽  
pp. 461-473 ◽  
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Effective Properties ◽  
Young's Modulus ◽  
Matrix Material ◽  
Practical Importance ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Two Dimensional ◽  
Isotropic Composite

Recent results of theoretical and practical importance prove that the two-dimensional (in-plane) effective (average) Young’s modulus for an isotropic elastic material containing voids is independent of the Poisson’s ratio of the matrix material. This result is true regardless of the shape and morphology of the voids so long as isotropy is maintained. The present work uses this proof to obtain explicit analytical forms for the effective Young’s modulus property, forms which simplify greatly because of this characteristic. In some cases, the optimal morphology for the voids can be identified, giving the shapes of the voids, at fixed volume, that maximize the effective Young’s modulus in the two-dimensional situation. Recognizing that two-dimensional isotropy is a subset of three-dimensional transversely isotropic media, it is shown in this more general case that three of the five properties are independent of Poisson’s ratio, leaving only two that depend upon it. For three-dimensionally isotropic composite media containing voids, it is shown that a somewhat comparable situation exists whereby the three-dimensional Young’s modulus is insensitive to variations in Poisson’s ratio, v m , over the range 0 ≤ v m ≤ ½, although the same is not true for negative values of v m . This further extends the practical usefulness of the two-dimensional result to three-dimensional conditions for realistic values of v m .

scholarly journals The investigation of internal pressure development in convective drying of shrinking and non-shrinking materials using green and fired clay as an example

2018 ◽  
Author(s):  
Anna Adamska ◽  
Zdzislaw Pakowski ◽  
Robert Adamski
Keyword(s):  
Internal Pressure ◽  
Control Method ◽  
Ambient Pressure ◽  
Ambient Pressure Drying ◽  
Convective Drying ◽  
Dynamic Changes ◽  
Pressure Development ◽  
Comparison Of The Results ◽  
Pressure Changes ◽  
Pressure Evolution

The aim of present research was to measure and analyze the dynamic changes of internal pressure in shrinking  vs.  non-shrinking materials during convective drying for the use as a possible process control method. Drying experiments were carried out on wet and fired clay at 50°C and 60°C. In addition, the shrinkage curve was investigated. Experimental measurements show the existence of 4 stages of the process. The comparison of the results for wet and fired clay shows differences in pressure trends. During drying the internal pressure changes from underpressure to overpressure at the level of 3÷5kPa, what correlates well with transition from the first to the second drying period. Keywords: ambient pressure drying; clay; shrinkage; pressure evolution  

scholarly journals Safety assessment of corrosion-defective natural gas pipeline under ground overload based on FEM

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
T, Zheng ◽  
Z. Liang ◽  
J. Zhang ◽  
S. Tang ◽  
X. Xiao
Keyword(s):  
Internal Pressure ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Local Stress ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Failure Pressure ◽  
Corrosion Defect ◽  
Corrosion Defects ◽  
Von Mises

Aiming at the safety problem of the pipeline containing corrosion defects caused by ground overload, a novel method is developed to assess the safety of buried pipelines with corrosion defects and predict the failure pressure. The effects of parameters including internal pressure, ground overload, length of the loading area, corrosion defect depth, buried depth and soil Young’s modulus, are discussed. Ground overload greatly increases the von Mises stress and strain at the corrosion defect location and decreases the internal pressure threshold. The von Mises stress and strain are an obvious nonlinear relationship with internal pressure. The high stress and strain area expand along the diagonal direction of the defect area. The local stress and strain concentration at the corrosion defect increases with the increase of ground overload, length of the loading area and corrosion defect depth, which reduces the failure pressure of the pipeline. Increasing the buried depth and soil Young’s modulus would effectively reduce local stress and strain concentration, and increase the failure pressure of the pipeline. The pipeline settlement displacement increases with the increase of internal pressure, ground overload, length of the loading area, and decreases with the increase of pipeline buried depth and soil Young’s modulus.

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

2019 ◽  
Vol 107 (2) ◽  
pp. 207 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Miroslav Karlík ◽  
Veronika Kadlecová ◽  
Jiří Čapek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Milling Time ◽  
Young's Modulus ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Particles ◽  
Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

Degradation of Rocks, Through Cracking Caused by Differential Thermal Expansion, in Relation to Nuclear Waste Repositories

1981 ◽  
Vol 6 ◽  
Author(s):  
J.R. Mclaren ◽  
R.W. Davidge ◽  
I. Titchell ◽  
K. Sincock ◽  
A. Bromley
Keyword(s):  
Thermal Expansion ◽  
Grain Boundary ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Crack Density ◽  
Granitic Rocks ◽  
Multiphase Materials ◽  
Thermal Expansion Behaviour ◽  
Waste Repositories ◽  
Expansion Behaviour

ABSTRACTHeating to temperatures up to 500°C, gives a reduction in Young's modulus and increase in permeability of granitic rocks and it is likely that a major reason is grain boundary cracking. The cracking of grain boundary facets in polycrystalline multiphase materials showing anisotropic thermal expansion behaviour is controlled by several microstructural factors in addition to the intrinsic thermal and elastic properties. Of specific interest are the relative orientations of the two grains meeting at the facet, and the size of the facet; these factors thus introduce two statistical aspects to the problem and these are introduced to give quantitative data on crack density versus temperature. The theory is compared with experimental measurements of Young's modulus and permeability for various rocks as a function of temperature. There is good qualitative agreement, and the additional (mainly microstructural) data required for a quantitative comparison are defined.

Is it necessary to calculate Young’s modulus in AFM nanoindentation experiments regarding biological samples?

2020 ◽  
Vol 12 ◽  
Author(s):  
S.V. Kontomaris ◽  
A. Malamou ◽  
A. Stylianou
Keyword(s):  
Young’S Modulus ◽  
Biological Samples ◽  
Young's Modulus ◽  
Reference Sample ◽  
Nonlinear Behavior ◽  
Accurate Method ◽  
Accurate Solution ◽  
Hertz Model ◽  
Work Done

Background: The determination of the mechanical properties of biological samples using Atomic Force Microscopy (AFM) at the nanoscale is usually performed using basic models arising from the contact mechanics theory. In particular, the Hertz model is the most frequently used theoretical tool for data processing. However, the Hertz model requires several assumptions such as homogeneous and isotropic samples and indenters with perfectly spherical or conical shapes. As it is widely known, none of these requirements are 100 % fulfilled for the case of indentation experiments at the nanoscale. As a result, significant errors arise in the Young’s modulus calculation. At the same time, an analytical model that could account complexities of soft biomaterials, such as nonlinear behavior, anisotropy, and heterogeneity, may be far-reaching. In addition, this hypothetical model would be ‘too difficult’ to be applied in real clinical activities since it would require very heavy workload and highly specialized personnel. Objective: In this paper a simple solution is provided to the aforementioned dead-end. A new approach is introduced in order to provide a simple and accurate method for the mechanical characterization at the nanoscale. Method: The ratio of the work done by the indenter on the sample of interest to the work done by the indenter on a reference sample is introduced as a new physical quantity that does not require homogeneous, isotropic samples or perfect indenters. Results: The proposed approach, not only provides an accurate solution from a physical perspective but also a simpler solution which does not require activities such as the determination of the cantilever’s spring constant and the dimensions of the AFM tip. Conclusion: The proposed, by this opinion paper, solution aims to provide a significant opportunity to overcome the existing limitations provided by Hertzian mechanics and apply AFM techniques in real clinical activities.

Effect of Microcrystalline Cellulose from Banana Stem Fiber on Mechanical Properties and Crystallinity of PLA Composite Films

2011 ◽  
Vol 695 ◽  
pp. 170-173 ◽  
Author(s):  
Voravadee Suchaiya ◽  
Duangdao Aht-Ong
Keyword(s):  
Tensile Strength ◽  
Young’S Modulus ◽  
Microcrystalline Cellulose ◽  
Young's Modulus ◽  
Agricultural Waste ◽  
Composite Films ◽  
Sem Image ◽  
Biocomposite Films ◽  
Twin Screw ◽  
Banana Stem

This work focused on the preparation of the biocomposite films of polylactic acid (PLA) reinforced with microcrystalline cellulose (MCC) prepared from agricultural waste, banana stem fiber, and commercial microcrystalline cellulose, Avicel PH 101. Banana stem microcrystalline cellulose (BS MCC) was prepared by three steps, delignification, bleaching, and acid hydrolysis. PLA and two types of MCC were processed using twin screw extruder and fabricated into film by a compression molding. The mechanical and crystalline behaviors of the biocomopsite films were investigated as a function of type and amount of MCC. The tensile strength and Young’s modulus of PLA composites were increased when concentration of MCC increased. Particularly, banana stem (BS MCC) can enhance tensile strength and Young’s modulus of PLA composites than the commercial MCC (Avicel PH 101) because BS MCC had better dispersion in PLA matrix than Avicel PH 101. This result was confirmed by SEM image of fractured surface of PLA composites. In addition, XRD patterns of BS MCC/PLA composites exhibited higher crystalline peak than that of Avicel PH 101/PLA composites

scholarly journals Out-of-Plane Thermal Expansion Coefficient and Biaxial Young’s Modulus of Sputtered ITO Thin Films

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 153
Author(s):  
Chuen-Lin Tien ◽  
Tsai-Wei Lin
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Young’S Modulus ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Young's Modulus ◽  
Heating Temperature ◽  
Glass Substrates ◽  
Ito Thin Films

This paper proposes a measuring apparatus and method for simultaneous determination of the thermal expansion coefficient and biaxial Young’s modulus of indium tin oxide (ITO) thin films. ITO thin films simultaneously coated on N-BK7 and S-TIM35 glass substrates were prepared by direct current (DC) magnetron sputtering deposition. The thermo-mechanical parameters of ITO thin films were investigated experimentally. Thermal stress in sputtered ITO films was evaluated by an improved Twyman–Green interferometer associated with wavelet transform at different temperatures. When the heating temperature increased from 30 °C to 100 °C, the tensile thermal stress of ITO thin films increased. The increase in substrate temperature led to the decrease of total residual stress deposited on two glass substrates. A linear relationship between the thermal stress and substrate heating temperature was found. The thermal expansion coefficient and biaxial Young’s modulus of the films were measured by the double substrate method. The results show that the out of plane thermal expansion coefficient and biaxial Young’s modulus of the ITO film were 5.81 × 10−6 °C−1 and 475 GPa.

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