Uniaxial Mechanical Properties of Sandstone under Cyclic of Drying and Wetting

2011 ◽  
Vol 243-249 ◽  
pp. 2310-2313 ◽  
Author(s):  
Hua Yan Yao ◽  
Zhen Hua Zhang ◽  
Zhao Hui Zhu
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Test Results ◽  
Stress Strain ◽  
Deformation And Failure ◽  
Deformation Behaviors ◽  
Uniaxial Strength

Water is an important factor that influences the mechanical properties of rock. Uniaxial compressive experiments have been carried out on sandstone under different cyclic times of drying and wetting. The corresponding complete stress-strain curves are obtained, and characteristics of deformation and failure are analyzed. Test results show that when sandstone samples are submitted to cyclic of drying and wetting, the uniaxial strength and Young's modulus of sandstone obviously decrease. Then, the improved Duncan constitutive model is developed, which can do better in describing sample’s deformation behaviors subject to different cyclic times of drying and wetting. Introduction

scholarly journals Effect of Nanopores on Mechanical Properties of the Shape Memory Alloy

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 529
Author(s):  
Chunzhi Du ◽  
Zhifan Li ◽  
Bingfei Liu
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Shape Memory ◽  
Young’S Modulus ◽  
Residual Strain ◽  
Surface Effect ◽  
Young's Modulus ◽  
Strain Curve ◽  
Stress Strain ◽  
Strength Limit

Nanoporous Shape Memory Alloys (SMA) are widely used in aerospace, military industry, medical and health and other fields. More and more attention has been paid to its mechanical properties. In particular, when the size of the pores is reduced to the nanometer level, the effect of the surface effect of the nanoporous material on the mechanical properties of the SMA will increase sharply, and the residual strain of the SMA material will change with the nanoporosity. In this work, the expression of Young’s modulus of nanopore SMA considering surface effects is first derived, which is a function of nanoporosity and nanopore size. Based on the obtained Young’s modulus, a constitutive model of nanoporous SMA considering residual strain is established. Then, the stress–strain curve of dense SMA based on the new constitutive model is drawn by numerical method. The results are in good agreement with the simulation results in the published literature. Finally, the stress-strain curves of SMA with different nanoporosities are drawn, and it is concluded that the Young’s modulus and strength limit decrease with the increase of nanoporosity.

Uniaxial compression mechanical properties and damage constitutive model of limestone under osmotic pressure

2021 ◽  
pp. 105678952110454
Author(s):  
Zhanping Song ◽  
Tong Wang ◽  
Junbao Wang ◽  
Kehui Xiao ◽  
TengTian Yang
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Osmotic Pressure ◽  
Uniaxial Compression ◽  
Influencing Factor ◽  
Peak Strain ◽  
Strain Response ◽  
Test Results ◽  
Stress Strain ◽  
Compaction Factor

To study the influence of osmotic pressure on the uniaxial compression mechanical properties of limestone, uniaxial compression tests were carried out on limestone specimens under different osmotic water pressure. The test results show that with the increase of osmotic pressure, the closure strain, yield strain and peak strain of limestone gradually increase, while the closure stress, yield stress, peak stress and elastic modulus gradually decrease. To describe the stress-strain response of limestone during uniaxial compression failure, the concepts of compaction factor and osmotic pressure influencing factor were proposed, and a constitutive model of rock compaction stage was established by integrating the relationship between the compaction factor and osmotic pressure influencing factor and the tangent modulus of compaction section. On this basis, combining the continuum damage mechanics theory, and assuming that the rock micro-unit strength obeys the compound power function distribution, a constitutive model reflecting the uniaxial compression mechanical properties of rock under osmotic pressure was established by the statistical method. The rationality of the model was verified using the results of the uniaxial compression test of limestone under different osmotic pressures. The results show that the test results under different osmotic pressures are in good agreement with the theoretical curves, and the model in this paper can reflect the stress-strain response of limestone before its failure under different osmotic pressures.

Relationship between Elastic Module and Porous Structure of Cancellous Bone

2018 ◽  
Vol 933 ◽  
pp. 309-313
Author(s):  
Yi Hao Du ◽  
Si Yuan He ◽  
Meng Ke Huo ◽  
Ping Zhou ◽  
Qiang Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Porous Structure ◽  
Trabecular Bone ◽  
Young’S Modulus ◽  
Cancellous Bone ◽  
Young's Modulus ◽  
Dominant Factor ◽  
Morphological Parameters ◽  
Elastic Module ◽  
Deformation Behaviors

Trabecular bone, widely presented in the ends of long bones and chine, is a typically porous structure which provides a multifunction such as light weight, undertaking load, impact energy buffer and hosting marrow cells. The structure of trabecular is a dominant factor for the strength of cancellous bone. The prediction of the trabecular bone’s mechanical properties depending on the trabecular structure is very useful for the diagnosis and treatment of osteoporosis. The object of this study is to establish a relationship between the mechanical properties and topological, morphological parameters of trabecular bone. The 50 3-D data of cancellous bone are selected from the CT images of three caput femurs and disposed in BoneJ, through which the BV/TV, SMI and genus parameters of each samples are obtained. The deformation behaviors of trabecular bone are simulated in ABAQUS through uniaxial compression on the 3-D model derived from stack images. Then linear-regression analyses are conducted on the BV/TV, genus, SMI and apparent Young’s modulus, resulting a high correlation (R^2=0.84) between the Young’s modulus and the hybrid parameter derived from SMI and normalized genus, corresponding to morphological and topological parameter of the samples respectively. The result indicates that it’s promising to establish the relationship between mechanical properties of trabecular bone and their topological and morphological parameters.

Experimental Setup for the Determination of Mechanical Solder Materials Properties at Elevated Temperatures

2010 ◽  
Vol 638-642 ◽  
pp. 3793-3798
Author(s):  
Wolfgang H. Müller ◽  
Holger Worrack ◽  
Jens Sterthaus
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Elevated Temperatures ◽  
Young's Modulus ◽  
Linear Optimization ◽  
Strain Curve ◽  
Stress And Strain ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Non Linear

The fabrication of microelectronic and micromechanical devices leads to the use of only very small amounts of matter, which can behave quite differently than the corresponding bulk. Clearly, the materials will age and it is important to gather information on the (changing) material characteristics. In particular, Young’s modulus, yield stress, and hardness are of great interest. Moreover, a complete stress-strain curve is desirable for a detailed material characterization and simulation of a component, e.g., by Finite Elements (FE). However, since the amount of matter is so small and it is the intention to describe its behavior as realistic as possible, miniature tests are used for measuring the mechanical properties. In this paper two miniature tests are presented for this purpose, a mini-uniaxial-tension-test and a nanoindenter experiment. In the tensile test the axial load is prescribed and the corresponding extension of the specimen length is recorded, both of which determines the stress-strain- curve directly. The stress-strain curves are analyzed by assuming a non-linear relationship between stress and strain of the Ramberg-Osgood type and by fitting the corresponding parameters to the experimental data (obtained for various microelectronic solders) by means of a non-linear optimization routine. For a detailed analysis of very local mechanical properties nanoindentation is used, resulting primarily in load vs. indentation-depth data. According to the procedure of Oliver and Pharr this data can be used to obtain hardness and Young’s modulus but not a complete stress-strain curve, at least not directly. In order to obtain such a stress-strain-curve, the nanoindentation experiment is combined with FE and the coefficients involved in the corresponding constitutive equations for stress and strain are obtained by means of the inverse method. The stress-strain curves from nanoindentation and tensile tests are compared for two mate-rials (aluminum and steel). Differences are explained in terms of the locality of the measurement. Finally, material properties at elevated temperature are of particular interest in order to characterize the materials even more completely. We describe the setup for hot stage nanoindentation tests in context with first results for selected materials.

Influence of calcium ions on the mechanical properties of a model biofilm of mucoid Pseudomonas aeruginosa

2001 ◽  
Vol 43 (6) ◽  
pp. 49-57 ◽  
Author(s):  
V. Körstgens ◽  
H.-C. Flemming ◽  
J. Wingender ◽  
W. Borchard
Keyword(s):  
Mechanical Properties ◽  
Pseudomonas Aeruginosa ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Calcium Ions ◽  
Extracellular Polymeric Substances ◽  
Young's Modulus ◽  
Critical Concentration ◽  
Strain Diagram ◽  
Stress Strain

The mechanical properties of biofilms and in particular their mechanical strength is of great importance for both biofilm reactors and for the removal of undesired biofilms as in cases of biofouling and biocorrosion. By uniaxial compression measurements, it is possible to determine the apparent elastic or Young's modulus and the yield stress as parameters for mechanical stability. This was performed with a recently developed device, using model biofilms of mucoid strain Pseudomonas aeruginosa SG81. The biofilms were grown on membrane filters placed on nutrient agar medium with different concentrations of calcium ions. The compressive stress - strain behaviour up to failure was recorded at a compression speed of 1 μm s-1. The apparent Young's modulus, representing the stiffness of the biofilm, and the yield stress obtained from the stress - strain diagram were used for the description of mechanical properties of biofilms. A certain critical concentration of calcium ions was found where the Young's modulus of the P. aeruginosa biofilms increases strongly and subsequently remains constant for higher calcium concentrations. This behaviour is explained by the presence of calcium ions crosslinking alginate, which is the major component of the extracellular polymeric substances produced by the mucoid P. aeruginosa strain used in this investigation.

scholarly journals Effect of Radiation on Topopah Spring Tuff Mechanical Properties

1996 ◽  
Vol 465 ◽  
Author(s):  
P. A. Berge ◽  
S. C. Blair
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Peak Strength ◽  
Test Results ◽  
Welded Tuff ◽  
Discernible Effect ◽  
And Control ◽  
Compressive Tests ◽  
Topopah Spring Tuff

ABSTRACTThe effect of radiation on the mechanical properties of Topopah Spring tuff was investigated by performing uniaxial compressive tests on irradiated and control samples of the tuff from the potential repository horizon at Yucca Mountain. Test results are presented, including stress-strain curves and peak strength and Young's modulus values. The results from this preliminary study show that for uncracked samples of Topopah Spring tuff, exposure to gamma radiation had no discernible effect on the unconfined compressive (peak) strength or the Young's modulus. However, results for samples that contained partially healed subvertical cracks indicate that exposure to radiation may reduce the strength and Young's modulus significantly. This is attributed to weakening of the cementing materials in the cracks and fractures of the samples that were irradiated. These results are preliminary, and additional studies are warranted to evaluate whether radiation weakens cementing materials in welded tuff.

Mechanical properties of SU-8

1998 ◽  
Vol 546 ◽  
Author(s):  
A. Mcaleavey ◽  
G. Coles ◽  
R. L. Edwards ◽  
W. N. Sharpe
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Test System ◽  
Gage Section ◽  
Average Strength ◽  
Stress Strain

AbstractAn existing test system for recording the stress-strain curves of metal microspecimens has been used to measure the strength of the ultrathick photoresist SU-8. The microspecimens are 3 mm long with a gage section 0.2 mm wide. The SU-8-25 specimens were 0.08 mm thick with an average strength of nearly 120 MPa, and the SU-8-50 specimens were 0.125 or 0.145 mm thick with an average strength of 130 MPa. Measurements of Young's modulus proved difficult, but a preliminary value of 3 GPa was obtained.

Modeling the Effect of Strain Rate on the Mechanical Properties of HDPE/Clay Nanocomposite Foams

2008 ◽  
Vol 16 (8) ◽  
pp. 561-575
Author(s):  
Choonghee Jo ◽  
Hani E. Naguib
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Constitutive Model ◽  
Strain Rate ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Favorable Effect ◽  
Logarithmic Scale ◽  
Nanocomposite Foams ◽  
Rate Of Increase

A constitutive model considering the effect of strain rate on the mechanical properties of semicrystalline polymer/clay nanocomposite foams was studied. Also, the influence of crystallinity on the effect of strain rate was incorporated in the model. High density polyethylene (HDPE)/clay nanocomposite foam was manufactured by a batch foaming process. Intercalated clay structures in the nanocomposite were investigated by means of transmission electron microscope (TEM), and the crystallinity of the material was measured using differential scanning calorimeter (DSC). Also, foam morphologies were studied by using scanning electron microscope (SEM). The favorable effect of nanoclay on the foaming was increased as crystallinity decreases. Also, the influence of crystallinity on the foaming decreased at high clay contents. The tensile strength of the foams increased linearly to the logarithmic scale of strain rate. The Young's modulus of the foams was reinforced by increasing the crystallinity. However, the rate of increase in the modulus was blunted as strain rate increases. Also, the Young's modulus increased gradually with increasing the strain rate, but the rate of increase diminished as crystallinity increases. This combining effect of strain rate and crystallinity on the Young's modulus was modeled and a viscoelastic stress-strain behavior of the foam was also proposed. The proposed constitutive model was validated by experiments.

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.

scholarly journals First principles computation of composition dependent elastic constants of omega in titanium alloys: implications on mechanical behavior

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Salloom ◽  
S. A. Mantri ◽  
R. Banerjee ◽  
S. G. Srinivasan
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
First Principles ◽  
Young's Modulus ◽  
Group Vi ◽  
Group V ◽  
Β Phase ◽  
Ti Alloys ◽  
Ω Phase ◽  
Stabilizer Concentration

AbstractFor decades the poor mechanical properties of Ti alloys were attributed to the intrinsic brittleness of the hexagonal ω-phase that has fewer than 5-independent slip systems. We contradict this conventional wisdom by coupling first-principles and cluster expansion calculations with experiments. We show that the elastic properties of the ω-phase can be systematically varied as a function of its composition to enhance both the ductility and strength of the Ti-alloy. Studies with five prototypical β-stabilizer solutes (Nb, Ta, V, Mo, and W) show that increasing β-stabilizer concentration destabilizes the ω-phase, in agreement with experiments. The Young’s modulus of ω-phase also decreased at larger concentration of β-stabilizers. Within the region of ω-phase stability, addition of Nb, Ta, and V (Group-V elements) decreased Young’s modulus more steeply compared to Mo and W (Group-VI elements) additions. The higher values of Young’s modulus of Ti–W and Ti–Mo binaries is related to the stronger stabilization of ω-phase due to the higher number of valence electrons. Density of states (DOS) calculations also revealed a stronger covalent bonding in the ω-phase compared to a metallic bonding in β-phase, and indicate that alloying is a promising route to enhance the ω-phase’s ductility. Overall, the mechanical properties of ω-phase predicted by our calculations agree well with the available experiments. Importantly, our study reveals that ω precipitates are not intrinsically embrittling and detrimental, and that we can create Ti-alloys with both good ductility and strength by tailoring ω precipitates' composition instead of completely eliminating them.

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