Investigation of Endochronic Constitutive Equation Subject to Plastic Strain-Controlled Axial-Torsional Deformation

1986 ◽  
Vol 108 (3) ◽  
pp. 262-269 ◽  
Author(s):  
Han C. Wu ◽  
J. C. Yao ◽  
S. C. Chu
Keyword(s):  
Plastic Strain ◽  
Theoretical Study ◽  
Test System ◽  
Torsional Deformation ◽  
Endochronic Theory ◽  
Phase Path ◽  
Strain Paths ◽  
Theoretical Results ◽  
Material Test System ◽  
Good Agreement

Plastic-strain controlled test is investigated both experimentally and theoretically. The plastic-strain control is feasible by means of computer-aided material test system. Theoretical study is made by use of the modified endochronic theory in which plastic strain is employed to define intrinsic time. Three in-phase plastic-strain paths (a pure axial path, a pure torsional path and an axial-torsional in-phase path) and two out-of-phase plastic-strain paths (small and large perturbations from the axial-torsional in-phase path) are studied. It is shown that the theory and experiment have good agreement. Furthermore, both experimental and theoretical results show that strain-hardening is enhanced by out-of-phase loading.

Analysis of Stress Response to Various Strain-Paths in Axial-Torsional Deformation of Metals

1984 ◽  
Vol 106 (4) ◽  
pp. 361-366 ◽  
Author(s):  
Han C. Wu ◽  
Jen-Che Yao
Keyword(s):  
Stress Response ◽  
Plastic Strain ◽  
Strain Path ◽  
Sensitivity Study ◽  
Total Strain ◽  
Torsional Deformation ◽  
Torsional Strain ◽  
Straight Line ◽  
Phase Path ◽  
Strain Paths

The stress response to various axial-torsional strain paths is discussed. The modified endochronic plasticity theory, which is formulated based on plastic-strain is used for theoretical analysis. In a sensitivity study, it is shown that a substantial amount of change in the stress response is induced by a small perturbation on the plastic-strain path. Of this change a significant amount is due to perturbation in the direction of the plastic-strain path. Several stepwise strain paths, both total-strain and plastic-strain paths, are also included in the investigation. It has been found that, when the number of steps is increased to infinity such that the strain path converges to a straight line corresponding to an in-phase path, the stress response to such a path is wildly fluctuating in the stress space if the path is a plastic-strain path, and the stress response converges to that of the in-phase path if the path is a total-strain path.

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

scholarly journals THEORETICAL STUDY OF THE EFFECT OF PROBE SHAPE ON ADHESION FORCE BETWEEN PROBE AND SUBSTRATE IN ATOMIC FORCE MICROSCOPE EXPERIMENT

2013 ◽  
Vol 43 (4) ◽  
pp. 61-72 ◽  
Author(s):  
Li Yang ◽  
Junhui Hu ◽  
Lingjiang Kong
Keyword(s):  
Atomic Force Microscope ◽  
Theoretical Study ◽  
Adhesion Force ◽  
Quantitative Description ◽  
Fundamental Parameters ◽  
Atomic Force ◽  
Combined Action ◽  
Theoretical Results ◽  
Good Agreement ◽  
Manipulation Experiment

Abstract The quantitative description of adhesion force dependence on the probe shape is of importance in many scientific and industrial fields. We performed a theoretical study on the influences of the probe shape (the sphere and parabolic probe) on the adhesion force at different humidity in order to elucidate how the adhesion force varied with the probe shape in atomic force microscope manipulation experiment. We found that the combined action of the triple point and the Kelvin radius is the guiding trend of the adhesion force, and these two fundamental parameters are closely related to the probe shape. Meanwhile, the theoretical results demonstrated that the adhesion force are in a good agreement with the experiment data if the van der Waals force is take into account.

Structural, Electronic and Elastic Properties of Palladium Nitride

2013 ◽  
Vol 665 ◽  
pp. 58-62 ◽  
Author(s):  
Nikita Acharya ◽  
Bushra Fatima ◽  
Sunil Singh Chouhan ◽  
Sankar P. Sanyal
Keyword(s):  
Theoretical Study ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Transition Metal Nitride ◽  
Generalized Gradient Approximation ◽  
Zinc Blende ◽  
Theoretical Results ◽  
Zinc Blende Structure ◽  
Good Agreement

A systematic theoretical study of 4dtransition metal nitride, PdN has been carried out using ab initio full potential LAPW method (FP-LAPW) within the generalized gradient approximation (GGA). PdN crystallizes in zinc-blende structure, which is found to be most stable one. We have calculated the ground state properties in terms of lattice constant (a0), Bulk modulus (B0) and its Pressure derivative (B0). The electronic properties such as band structure and density of states reveal that PdN is metallic in nature with large overlap of Pd-delectron at Fermi level. The elastic constant are in good agreement with previous theoretical results for zinc-blende structure.

scholarly journals G EXPERIMENTAL AND THEORETICAL STUDY OF FORCED CONVECTION AROUND A CYLINDER EMBEDDED IN POROUS MEDIA

2020 ◽  
Vol 20 (2) ◽  
pp. 164-179
Author(s):  
Abeer Aamer ◽  
Suhad Abd-hameed
Keyword(s):  
Heat Transfer ◽  
Porous Material ◽  
Forced Convection ◽  
Test Section ◽  
Average Nusselt Number ◽  
Theoretical Study ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Theoretical Results ◽  
Good Agreement

An experimental and theoretical study of air forced convection heat transfer at Reynoldsnumber (1091.5 to 1560) around a circular cylinder placed in an iron test section (0.2x0.2x0.4m3) filled with saturated porous material glass balls of 5mm in diameter. A copper circularcylinder heater of diameter 0.015m and length 0.2m is heated electrically; it is located indifferent positions in X and Y direction within the test section. The forced convection heattransfer is simulated using the ANSYS program (Fluent). The results showed that the surfacetemperature distribution of the cylinder has the same trends for the different locations withinthe test section. The average Nusselt number increases with Reynolds number and heat flux.Also, the results show that the use of porous material improves heat transfer by 67.4%. Themaximum percentage deviation between the experimental and theoretical results is 1.622%.Moreover, experimental correlations were introduced and comparison was performedbetween the present results with the previous studies and it gives a good agreement.

A review of stress-strain paths and constitutive relations in the plastic range

1981 ◽  
Vol 16 (4) ◽  
pp. 235-249 ◽  
Author(s):  
D W A Rees
Keyword(s):  
Plastic Strain ◽  
Radial Stress ◽  
Strain Path ◽  
Stress Path ◽  
Biaxial Stress ◽  
Strain History ◽  
Hardening Rule ◽  
Non Linear ◽  
Strain Paths ◽  
Good Agreement

Plastic strain paths produced by both radial and non-radial stress paths are reviewed for metals and alloys under uniaxial and biaxial stress. The present interpretation illustrates collective trends and offers theoretical solutions for each of several stress paths. In general the strain path is linear for a radial stress path for most materials at low to medium temperatures. The isotropic quadratic hardening rule of von Mises rarely describes the strain behaviour accurately. but a simple anisotropic quadratic form provides good agreement by the uniform hardening rule. Exceptions are found for magnesium and an associated alloy at room temperature and for the high temperature deformation in an aluminium alloy. Descriptive yield functions are presented and the anistropic constants determined for one particular function of the Bailey form. Strain paths produced by outward non radial zig-zag and stepped stress paths are approximately linear provided that they are confined to a narrow band in stress space. It is shown that an equivalent radial stress path analysis provides good agreement with experiment. The strain paths resulting from stress paths containing corners and from paths composed of partial or complete unloading followed by reloading in a different direction are non-linear. The behaviour is attributed to strain history; namely, a Bauschinger effect where unloading occurs and an interaction between direction dependent plastic strains for stress paths containing corners. For unloading-reloading paths a rotation in the strain path towards a linear direction is indicative of the transient nature of strain history. Good agreement is found with the prediction from each of three rules of anisotropic hardening. They are thus generalized to provide the plastic strain response to any stress path that is composed of linear segments. Modifications that account for the effects of non-linear work hardening and creep are discussed.

Rate coefficients for the reaction of OH radicals with cis-3-hexene: an experimental and theoretical study

2015 ◽  
Vol 17 (14) ◽  
pp. 8714-8722 ◽  
Author(s):  
Thaís da Silva Barbosa ◽  
Silvina Peirone ◽  
Javier A. Barrera ◽  
Juan P. A. Abrate ◽  
Silvia I. Lane ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Experimental Rate ◽  
Theoretical Results ◽  
Good Agreement

Microcanonical variational rate coefficients and experimental rate coefficients for the OH addition to cis-3-hexene have been determined. Theoretical results showed a non-Arrhenius profile and good agreement with the experimental data.

scholarly journals Theoretical study of the adsorption of benzene on coinage metals

2014 ◽  
Vol 10 ◽  
pp. 1775-1784 ◽  
Author(s):  
Werner Reckien ◽  
Melanie Eggers ◽  
Thomas Bredow
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Dispersion Correction ◽  
Functional Theory ◽  
Coinage Metals ◽  
Adsorption Energies ◽  
Theoretical Results ◽  
Good Agreement

The adsorption of benzene on the M(111), M(100) and M(110) surfaces of the coinage metals copper (M = Cu), silver (M = Ag) and gold (M = Au) is studied on the basis of density functional theory (DFT) calculations with an empirical dispersion correction (D3). Variants of the Perdew–Burke–Ernzerhof functionals (PBE, RPBE and RevPBE) in combination with different versions of the dispersion correction (D3 and D3(BJ)) are compared. PBE-D3, PBE-D3(BJ) and RPBE-D3 give similar results which exhibit a good agreement with experimental data. RevPBE-D3 and RevPBE-D3(BJ) tend to overestimate adsorption energies. The inclusion of three-center terms (PBE-D3(ABC)) leads to a slightly better agreement with the experiment in most cases. Vertical adsorbate–substrate distances are calculated and compared to previous theoretical results. The observed trends for the surfaces and metals are consistent with the calculated adsorption energies.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

Studies of local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) crystals

2021 ◽  
Vol 76 (4) ◽  
pp. 299-304
Author(s):  
Fu Chen ◽  
Jian-Rong Yang ◽  
Zi-Fa Zhou
Keyword(s):  
Crystal Field ◽  
Elongation Ratio ◽  
Paramagnetic Resonance ◽  
Local Structures ◽  
Epr Parameters ◽  
Structure Constants ◽  
Crystal Field Parameters ◽  
Electron Paramagnetic ◽  
Theoretical Results ◽  
Good Agreement

Abstract The electron paramagnetic resonance (EPR) parameters (g factor g i , and hyperfine structure constants A i , with i = x, y, z) and local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) are theoretically investigated using the high order perturbation formulas of these EPR parameters for a 3d 9 ion under orthorhombically elongated octahedra. In the calculations, contribution to these EPR parameters due to the admixture of d-orbitals in the ground state wave function of the Cu2+ ion are taken into account based on the cluster approach, and the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the studied EPR parameters with the local structures of the Cu2+ centers. Based on the calculations, the Cu–H2O bonds are found to suffer the axial elongation ratio δ of about 3 and 2.9% along the z-axis, meanwhile, the planar bond lengths may experience variation ratio τ (≈3.8 and 1%) along x- and y-axis for Cu2+ center in (NH4)2Zn(SO4)2·6H2O and Rb2Zn(SO4)2·6H2O, respectively. The theoretical results show good agreement with the observed values.

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