Effect Of Torsional Deformation Research Articles

Torsional deformation effect on the N—H bond dissociation energy in diphenylamine

Abstract In this work, the influence of the inter-ring dihedral angles and their deformation on the energetics of diphenylamine molecule and its radical is investigated by the B3LYP/6-311++G** approach. Our approximated bond dissociation enthalpy of diphenylamine is 370.0 kJ mol-1 and it is in good agreement with the recently published experimental data. The potential functions of both the molecule and the radical with respect to the mutual aromatic ring orientations are presented. The potential function for the molecule is of a double-barrier type, whereas the radical possesses a single-barrier function. The calculated total electronic energies are used to approximate the change of the bond dissociation enthalpy with the twisting of the dihedral angle. The dependence of the bond dissociation enthalpy on the dihedral angle is represented by a single-barrier type function. The dependence of the nitrogen atom spin density on the studied dihedral angle is also discussed.

The effect of torsional deformation on thermal conductivity of mono-, bi- and trilayer graphene nanoribbon

Physical deformation and geometrical change of a low dimensional nanostructure influence the phonon transport leading to appreciable changes in the thermal characteristics. In this paper, we report the calculation of the thermal conductivity of twisted graphene nanoribbon (GNR) using nonequilibrium molecular dynamics (NEMD). A reduction in the value of thermal conductivity of GNR is observed with an increase in the angle of twist. It is observed that the value of thermal conductivity of twisted GNR is dependent on the length of GNR and the temperature at which physical deformation is taking place. Comparing with monolayer GNR, the reduction in the thermal conductivity of bilayer and trilayer GNR is less due to the interactions between the adjacent layers. Analysis of the phonon transport in twisted graphene implies that the reduced thermal conductivity of twisted graphene nanoribbon is due to the phonon softening of acoustic phonon modes.

Effect of Torsional Deformation on the Recrystallization of Bubble Strengthened Tungsten

Effect of Torsional Deformation on the Recrystallization of Bubble Strengthened Tungsten

Effect of plastic deformation and radiation damage on the electrical resistivity changes in tantalum

The effect of torsional deformation on the electrical resistivity changes, Δρ ρ 0 , in tantalum wires was examined for unirradiated and irradiated specimens. Δρ ρ 0 was found to increase with \\ ̄ gg (mean torsional shear strain) in a manner described by Δρ ρ 0 = A γ m where m was found to be 0.81 at \\ ̄ gg < 140% and 0.25 at \\ ̄ gg > 140% for measurements at room temperature. At liquid nitrogen temperature m was found to be 1.9 at \\ ̄ gg < 70 % and 0.4 at \\ ̄ gg > 70 % . These results indicate that the electrical resistivity changes arise mainly from point defects at early stages of deformation and at low temperatures. At later stages of deformation the contribution arises mainly from dislocations. The changes in Δρ ρ 0 for wires irradiated in a fast integrated neutron dose from 2.25 × 10 17 n/ cm 2 up to 2.16 × 10 18 n/ cm 2 were less than in unirradiated specimens. This was attributed to defect annihilation arising from the interaction between defects generated by cold working and radiation-induced defects.

The Effect of Torsional Deformation on the Fatigue Strength of Carbon Steel

Hereunder is presented a report of studies made on the influence of preliminary workings on the fatigue strength of carbon steel. The effects of residual stress and structural change that are produced by cold-workings on the fatigue strength are discussed. For the increase of fatigue strength, in the case of uniaxial deformation like tension or compression, as previously reported, the structural change is considered to be more responsible than residual stress. In the case of biaxial deformation like torsion, however, these fatigue behaviours are not clarified yet.In this paper, the effect of torsional preliminary working on the fatigue strength of S45C steel is discussed in comparison with that of tensile and compressive preliminary workings. The results obtained are summarized as follows:(1) The residual stress produced by torsional deformation assumes a shearing state in the direction counter to the twisting direction that has been previously given.(2) The materials subjected to preliminary workings, in plastic deformation by three kinds of strain, twisting, stretching and compressing, each to equal level of degrees, have shown increase in fatigue strength quantitatively in the descending order as follows;twisting strain>stretching strain>compressing strain(3) The fatigue limit of twisted specimen continues to increase until such a straining as e*=0.400, and then it tends steeply to decrease. Considering the stress strate of twisted specimens, it is concluded that the residual stress due to the preliminary working does not affect the fatigue limit, although the apparent stress amplitude increases with the shearing residual stress. The fractured surface is considered as apt to be preliminary influenced by the shearing residual stress.(4) From the results of the tension test and the compression test of each strained specimen, it is apparent that the yield point for reversal direction of the deformed direction is lower than that of the annealed specimen because of Bauschinger's effect in the case of stretched and compressed specimen. On the other hand, the yield points in both the tensile and the compressive directions in the case of twisted specimen increase over that of the annealed specimen. These anisotropy of work-hardening is considered to contribute to the result that the fatigue strength of twisted specimen is largest among the preliminary strained specimens in the same amount of equivalent plastic strain by the three kinds of straining processes.

金属の剛性率に及ぼす捩り加工の影響に関する研究

金属の剛性率に及ぼす捩り加工の影響に関する研究