The dependences of the elastic stiffness moduli and the Poisson ratio of natural iron pyrites FeS2upon pressure and temperature

1989 ◽  
Vol 22 (5) ◽  
pp. 670-675 ◽  
Author(s):  
N Benbattouche ◽  
G A Saunders ◽  
E F Lambson ◽  
W Honle
Keyword(s):  
Poisson Ratio ◽  
Elastic Stiffness ◽  
Natural Iron ◽  
Iron Pyrites

scholarly journals 3D analysis of pore effect on composite elasticity by means of the finite-element method

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. L15-L26
Author(s):  
Akira Yoneda ◽  
Ferdous Hasan Sohag
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Poisson Ratio ◽  
Matrix Material ◽  
Elastic Stiffness ◽  
3D Analysis ◽  
3D Space ◽  
Porosity Effect ◽  
Derivatives Of ◽  
Element Method

We developed a 3D buffer-layer finite-element method model to investigate the porosity effect on macroscopic elasticity. Using the 3D model, the effect of pores on bulk effective elastic properties was systematically analyzed by changing the degree of porosity, the aspect ratio of the ellipsoidal pore, and the elasticity of the material. The results in 3D space were compared with the previous results in 2D space. Derivatives of normalized elastic stiffness constants with respect to needle-type porosity were integers, if the Poisson ratio of a matrix material was zero; those derivatives of normalized stiffness elastic constants for [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] converged to [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively, at the corresponding condition. We have developed a criterion of [Formula: see text], where the mutual interaction between pores became negligible for macroscopic composite elasticity. These derivatives were nearly constant at less than 5% porosity in the case of a spherical pore, suggesting that the interaction between neighboring pores was insignificant if the representative size of the pore was less than one-third of the mean distance between neighboring pores. The relations we obtained in this work were successfully applied to invert the bulk modulus and rigidity of [Formula: see text] as a case study; the performance of the inverting scheme was confirmed through this assessment. Thus, our scheme is applicable to predict the macroscopic elasticity of porous object as well.

Structural, electronic and elastic properties of ZnGeN2 and WZ-GaN under different hydrostatic pressures: A first-principle study

2019 ◽  
Vol 33 (25) ◽  
pp. 1950297 ◽  
Author(s):  
S. Chandra ◽  
V. Kumar
Keyword(s):  
Band Gap ◽  
Elastic Properties ◽  
Density Functional ◽  
Poisson Ratio ◽  
Elastic Stiffness ◽  
Phase Changes ◽  
First Principle ◽  
Direct Band Gap ◽  
Direct Band ◽  
G Ratio

The structural, electronic and elastic properties of orthorhombic ZnGeN2 and wurtzite (WZ)-GaN semiconductors have been studied under different pressures using first-principle density functional theory (DFT) calculations. The lattice constants (a, b and c) and energy bandgaps ([Formula: see text]) have been calculated under ambient condition. The elastic properties such as elastic stiffness constants ([Formula: see text]), shear modulus (G), bulk modulus (B), Young modulus ([Formula: see text]), B/G ratio and Poisson ratio ([Formula: see text]) have been studied at 50, 100, 110, 120, 150, 160, 180 and 190 GPa pressures for the first time as well as at 0 GPa. The calculated values of [Formula: see text] show that the ZnGeN2 and GaN are stable up to 180 and 150 GPa, respectively, and afterwards phase changes and become unstable. The band structure of ZnGeN2 reveals direct band gap behavior up to 100 GPa and becomes indirect band gap at 110 GPa. However, GaN is direct band gap up to 150 GPa and becomes indirect at 160 GPa. Comparing the results of both semiconductors, it is observed that ZnGeN2 is similar to WZ-GaN up to 100 GPa in all respect and can be used in many applications in place of WZ-GaN. The calculated values of all parameters are in reasonable agreement with the known values.

Postmortem and in situ TEM methods to study the mechanism of failure in controlled-morphology high-impact polystrene resin

1996 ◽  
Vol 54 ◽  
pp. 178-179
Author(s):  
R. C. Cieslinski ◽  
M. T. Dineen ◽  
J. L. Hahnfeld
Keyword(s):  
Poisson Ratio ◽  
Acrylonitrile Butadiene Styrene ◽  
High Impact ◽  
In Situ Tem ◽  
Styrene Copolymers ◽  
Controlled Morphology ◽  
Point Bend ◽  
Mechanism Of Failure ◽  
Impact Energies

Advanced Styrenic resins are being developed throughout the industry to bridge the properties gap between traditional HIPS (High Impact Polystyrene) and ABS (Acrylonitrile-Butadiene-Styrene copolymers) resins. These new resins have an unprecedented balance of high gloss and high impact energies. Dow Chemical's contribution to this area is based on a unique combination of rubber morphologies including labyrinth, onion skin, and core-shell rubber particles. This new resin, referred as a controlled morphology resin (CMR), was investigated to determine the toughening mechanism of this unique rubber morphology. This poster will summarize the initial studies of these resins using the double-notch four-point bend test of Su and Yee, tensile stage electron microscopy, and Poisson Ratio analysis of the fracture mechanism.

Comparison of the viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate)

1979 ◽  
Vol 44 (6) ◽  
pp. 1942-1948 ◽  
Author(s):  
Jaroslav Hrouz ◽  
Michal Ilavský ◽  
Ivan Havlíček ◽  
Karel Dušek
Keyword(s):  
Methyl Acrylate ◽  
Poisson Ratio ◽  
Young Modulus ◽  
Ethyl Acrylate ◽  
Sample Volume ◽  
Viscoelastic Behaviour ◽  
Tensile Behaviour ◽  
Temperature Superposition ◽  
Main Transition

The viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate) in the main transition region have been investigated. It was found that the time-temperature superposition could be carried out in the case of the penetration viscoelastic behaviour; the temperature dependence of the penetration and tensile shift factors was the same. The superimposed curves of the penetration and Young modulus allowed us to calculate the dependence of the Poisson ratio and thus to characterize the change in sample volume with deformation. It was demonstrated that the penetration method of determination of the viscoelastic behaviour is equivalent to the tensile method.

Transformation of Structure, Magnetic Properties and Microwave Absorption Capability in Nd-Doped Strontium Hexaferrite

2020 ◽  
Vol 855 ◽  
pp. 255-260
Author(s):  
Mukhtar Effendi ◽  
Efi Solihah ◽  
Candra Kurniawan ◽  
Wahyu Tri Cahyanto ◽  
Wahyu Widanarto
Keyword(s):  
Magnetic Properties ◽  
Microwave Absorption ◽  
Solid State Reaction Method ◽  
Strontium Hexaferrite ◽  
Basic Material ◽  
X Ray Diffraction ◽  
Cell Parameters ◽  
Tetragonal Crystal ◽  
Capability Analysis ◽  
Natural Iron

The synthesize of Nd3+-strontium hexaferrite magnetic material by the solid-state reaction method has been successfully carried out. This study aims to determine the effect of Nd3+ on the structure, magnetic properties, and microwave absorption capability of the material. Preparation of (1-x)SrO:xNd2O3:6Fe2O3 where x = 0, 10, 20, and 30 mol% using basic material in the form of SrCO3 powder, Nd2O3 powder and Fe3O4 from natural iron sand. The characterization includes the X-Ray Diffraction (XRD) examination to determine the crystal structure, the Scanning Electron Microscope (SEM) for exploring the surface morphology, Vibrating Sample Magnetometer (VSM) for the magnetic properties investigation of material, and Vector Network Analyzer (VNA) for microwave absorption capability analysis. The XRD results show that the addition of Nd3+ doping increases the number of SrNdFeO4 phases. The phase has a tetragonal crystal system that has cell parameters a = b = 3.846 Å, and c = 12.594 Å. The magnetic properties of the material showed that the addition of Nd3+ decreased the saturation and remanence magnetization values, whereas the value of the coercivity field increased. Meanwhile, the best microwave absorption occurs in samples with the addition of Nd3+ as much as 0.3 mol, which results in a reflection loss value of -18.9 dB with a frequency bandwidth of 3.9 GHz.

scholarly journals Sensitivity Based Selection of an Optimal Cable-Driven Parallel Robot Design for Rehabilitation Purposes

Robotics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Ferdaws Ennaiem ◽  
Abdelbadiâ Chaker ◽  
Juan Sebastián Sandoval Arévalo ◽  
Med Amine Laribi ◽  
Sami Bennour ◽  
...  
Keyword(s):  
Pareto Front ◽  
Parallel Robot ◽  
Elastic Stiffness ◽  
Upper Limb Rehabilitation ◽  
Daily Life Activities ◽  
System A ◽  
The Monte Carlo Method ◽  
Genetic Algorithm Method ◽  
Limb Rehabilitation ◽  
Selection Of

This paper deals with the design of an optimal cable-driven parallel robot (CDPR) for upper limb rehabilitation. The robot’s prescribed workspace is identified with the help of an occupational therapist based on three selected daily life activities, which are tracked using a Qualisys motion capture system. A preliminary architecture of the robot is proposed based on the analysis of the tracked trajectories of all the activities. A multi-objective optimization process using the genetic algorithm method is then performed, where the cable tensions and the robot size are selected as the objective functions to be minimized. The cables tensions are bounded between two limits, where the lower limit ensures a positive tension in the cables at all times and the upper limit represents the maximum torque of the motor. A sensitivity analysis is then performed using the Monte Carlo method to yield the optimal design selected out of the non-dominated solutions, forming the obtained Pareto front. The robot with the highest robustness toward the disturbances is identified, and its dexterity and elastic stiffness are calculated to investigate its performance.

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