Behaviour and simulation of sedimentary rocks

1967 ◽  
Vol 2 (4) ◽  
pp. 307-316 ◽  
Author(s):  
D W Hobbs
Keyword(s):  
Tensile Strength ◽  
Elastic Properties ◽  
Triaxial Compression ◽  
Sedimentary Rocks ◽  
Model Material ◽  
Scale Model ◽  
Dimensionless Analysis

Investigations on the elastic properties and strength of sedimentary rocks in uniaxial and triaxial compression and on the tensile strength of sedimentary rocks are described. A brief account is given of the application of dimensionless analysis to scale-model roadway tests and of the properties of a scale-model material.

scholarly journals A parametric prediction of the Young’s modulus of polymers enhanced with ΜWCNTs

2018 ◽  
Vol 233 ◽  
pp. 00025
Author(s):  
P.V. Polydoropoulou ◽  
K.I. Tserpes ◽  
Sp.G. Pantelakis ◽  
Ch.V. Katsiropoulos
Keyword(s):  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Experimental Results ◽  
Scale Model ◽  
Fe Model ◽  
Multi Scale ◽  
Unit Cells ◽  
Random Dispersion

In this work a multi-scale model simulating the effect of the dispersion, the waviness as well as the agglomerations of MWCNTs on the Young’s modulus of a polymer enhanced with 0.4% MWCNTs (v/v) has been developed. Representative Unit Cells (RUCs) have been employed for the determination of the homogenized elastic properties of the MWCNT/polymer. The elastic properties computed by the RUCs were assigned to the Finite Element (FE) model of a tension specimen which was used to predict the Young’s modulus of the enhanced material. Furthermore, a comparison with experimental results obtained by tensile testing according to ASTM 638 has been made. The results show a remarkable decrease of the Young’s modulus for the polymer enhanced with aligned MWCNTs due to the increase of the CNT agglomerations. On the other hand, slight differences on the Young’s modulus have been observed for the material enhanced with randomly-oriented MWCNTs by the increase of the MWCNTs agglomerations, which might be attributed to the low concentration of the MWCNTs into the polymer. Moreover, the increase of the MWCNTs waviness led to a significant decrease of the Young’s modulus of the polymer enhanced with aligned MWCNTs. The experimental results in terms of the Young’s modulus are predicted well by assuming a random dispersion of MWCNTs into the polymer.

Correlations between flow resistance and geometry in a model of the human nose

1993 ◽  
Vol 75 (4) ◽  
pp. 1767-1775 ◽  
Author(s):  
S. Schreck ◽  
K. J. Sullivan ◽  
C. M. Ho ◽  
H. K. Chang
Keyword(s):  
Nasal Congestion ◽  
Magnetic Resonance Images ◽  
Healthy Male Subject ◽  
Scale Model ◽  
Good Correspondence ◽  
Cross Sectional ◽  
Circular Duct ◽  
Pressure Losses ◽  
Dimensionless Analysis

The relationship between the pressure losses within the nasal airways and nasal geometry were studied in a 3:1 scale model. The geometry of the model was based on magnetic resonance images of the skull of a healthy male subject. Pressure measurements, flow visualization, and hot-wire anemometry studies were performed at flow rates that, in vivo, corresponded to flows of between 0.05 and 1.50 l/s. The influence of nasal congestion and the collapse of the external nares were examined by using modeling clay to simulate local constrictions in the cross section. A dimensionless analysis of the pressure losses within three sections of the airway revealed the influence of various anatomic dimensions on nasal resistance. The region of the exterior nose behaves as a contraction-expansion nozzle in which the pressure losses are a function of the smallest cross-sectional area. Losses in the interior nose resemble those associated with channel flow. The nasopharynx is modeled as a sharp bend in a circular duct. Good correspondence was found between the predicted and actual pressure losses in the model under conditions that stimulated local obstructions and congestion.

Mechanical and electronic properties of Ti-7333 alloy under tension: First-principles calculations

2020 ◽  
Vol 34 (17) ◽  
pp. 2050150
Author(s):  
Dan Hong ◽  
Wei Zeng ◽  
Fu-Sheng Liu ◽  
Bin Tang ◽  
Qi-Jun Liu
Keyword(s):  
Tensile Strength ◽  
Electronic Properties ◽  
Elastic Properties ◽  
First Principles ◽  
Structural Parameters ◽  
Tension Stress ◽  
Mechanical Parameters ◽  
First Principles Calculations ◽  
Anisotropic Behavior ◽  
Resistance To Deformation

The first-principles calculations are used to investigate the effects on mechanical and electronic properties of Ti-7333 alloy under the tension stress along [001], [100] and [110] directions. First, we study the structure and elastic properties of Ti-7333 alloy with 2, 16, 54 and 128 atoms, finding that the structural parameters of four models are comparative due to the approximate value of c/a and the elastic properties are also similar. Hence, we choose Ti-7333 alloy with 16 atoms to study the effects on mechanical and electronic properties under tension stress along [001], [100] and [110] directions. The changes of independent elastic constants, Debye temperature and anisotropic behavior under different tension stress along all the three directions can reflect that the tensile strength of Ti-7333 alloy may exist between [Formula: see text] and [Formula: see text] GPa and also find that it is easier to change the resistance to deformation of Ti-7333 alloy under the tension stress along [100] direction compared with [001] and [110] directions. What’s more, the calculated mechanical parameters show that the Ti-7333 alloy is brittle and the tendency of variations is small with the increase in tension stress. The effects on electronic properties including metallic and covalent properties are not obvious due to the approximate height of TDOS, pseudogap and charge density.

scholarly journals A simple way to use X-ray micro-tomography to infer elastic properties of heterogeneous materials: application to sedimentary rocks

2019 ◽  
Vol 55 (8) ◽  
pp. 3347-3353
Author(s):  
Pierre-Louis Valdenaire ◽  
Jonathan Perrin ◽  
Olivier Grauby ◽  
Franz-Josef Ulm ◽  
Roland J. M. Pellenq
Keyword(s):  
Elastic Properties ◽  
Sedimentary Rocks ◽  
Heterogeneous Materials ◽  
X Ray ◽  
Micro Tomography

Experimental Investigation into the Influences of Weathering on the Mechanical Properties of Sedimentary Rocks

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaoshuang Li ◽  
Yingchun Li ◽  
Saisai Wu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Friction Coefficient ◽  
Uniaxial Compression ◽  
Sedimentary Rocks ◽  
Uniaxial Tensile ◽  
Mechanical Parameters ◽  
Uniaxial Tensile Strength ◽  
Weathering Grades

The time-dependent behaviors of the sedimentary rocks which refer to the altering of the mechanical and deformable properties of rock elements in the long-term period are of increasing importance in the investigation of the failure mechanism of the rock strata in underground coal mines. In order to obtain the accurate and reliable mechanical parameters of the sedimentary rocks at different weathering grades, the extensive experimental programs including the Brazilian splitting test, uniaxial compression tests, and direct shear tests have been carried out on the specimens that exposed to the nature environments at different durations. The correlation between the weathering grades and mechanical parameters including uniaxial tensile strength, uniaxial compression strength, elastic modulus, Poisson’s ratio, cohesion, and friction coefficient was proposed. The obtained results suggested that uniaxial tensile strength, uniaxial compressive strength, elastic modulus, and cohesion dramatically decreased with increasing weathering time, characterized as the negative exponential relationship in general. The influences of various weathering grades on fracture behavior of the rock specimens were discussed. The cumulative damage of the rock by the weathering time decreased the friction coefficient of the specimens which led to the initiation and propagation of microcrack within the rock at lower stress conditions. The obtained results improved the understanding of the roles of weathering on the mechanical properties of sedimentary rocks, which is helpful in the design of the underground geotechnical structures.

scholarly journals Triaxial Strength Criteria in Mohr Stress Space for Intact Rocks

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Baohua Guo ◽  
Long Wang ◽  
Yizhe Li ◽  
Yan Chen
Keyword(s):  
Tensile Strength ◽  
Compression Strength ◽  
Triaxial Compression ◽  
Stress Space ◽  
Failure Envelope ◽  
Limit Values ◽  
Strength Criteria ◽  
Triaxial Strength ◽  
Failure Envelopes ◽  
Exponential Equations

Conventional triaxial strength criteria are important for the judgment of rock failure. Linear, parabolic, power, logarithmic, hyperbolic, and exponential equations were, respectively, established to fit the conventional triaxial compression test data for 19 types of rock specimens in the Mohr stress space. Then, a method for fitting the failure envelope to all common tangent points of each two adjacent Mohr’s circles (abbreviated as CTPAC) was proposed in the Mohr stress space. The regression accuracy of the linear equation is not as good as those of the nonlinear equations on the whole, and the regression uniaxial compression strength (σc)r, tensile strength (σt)r, cohesion cr, and internal frictional angle φr predicted by the regression linear failure envelopes with the method for fitting the CTPAC in the Mohr stress space are close to those predicted in the principal stress space. Therefore, the method for fitting CTPAC is feasible to determine the failure envelopes in the Mohr stress space. The logarithmic, hyperbolic, and exponential equations are recommended to obtain the failure envelope in the Mohr stress space when the data of tensile strength (σt)t are or are not included in regression owing to their higher R2, less positive x-intercepts, and more accurate regression cohesion cr. Furthermore, based on the shape and development trend of the nonlinear strength envelope, it is considered that when the normal stress is infinite, the total bearing capacity of rock tends to be a constant after gradual increase with decreasing rates. Thus, the hyperbolic equation and the exponential equation are more suitable to fit triaxial compression strength in a higher maximum confining pressure range because they have limit values. The conclusions can provide references for the selection of the triaxial strength criterion in practical geotechnical engineering.

Effect of Elastane and Thread Density on Mechanical Attributes of Stretch Woven Fabric

2020 ◽  
Vol 7 (1) ◽  
pp. 21-30
Author(s):  
Fahmida Siddiqa ◽  
Md. Mahbubul Haque ◽  
Shamima Akter Smriti ◽  
Nawshin Farzana ◽  
Abu Naser MD. Ahsanul Haque
Keyword(s):  
Tensile Strength ◽  
Elastic Properties ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Number Of Factors ◽  
And Performance ◽  
Tearing Strength

Stretch woven fabrics continue to grow in popularity, offering superior elastic properties and comfort. However, there are a number of factors (e.g., elongation, recovery, growth, tensile strength, tearing strength, and shrinkage) that can affect the attributes and performance of stretch woven fabric. These were investigated in the present study in relation to different elastane content and thread density. Blended cotton woven fabrics containing an increased elastane content gave enhanced elongation and recovery, despite a decrease in thread density. The tensile strength, tearing strength, shrinkage, and fabric growth decreased when the elastane ratio increased, regardless of the decline in warp thread density.

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