Considering strain localization in the form of a narrow band initiated just at peak stress, three analytical expressions for stressstrain curves of quasibrittle geomaterial (such as rock and concrete) in uniaxial tens...Considering strain localization in the form of a narrow band initiated just at peak stress, three analytical expressions for stressstrain curves of quasibrittle geomaterial (such as rock and concrete) in uniaxial tension, direct shear and uniaxial compression were presented, respectively. The three derived stressstrain curves were generalized as a unified formula. Beyond the onset of strain localization, a linear strain-softening constitutive relation for localized band was assigned. The size of the band was controlled by internal or characteristic length according to gradient-dependent plasticity. Elastic strain within the entire specimen was assumed to be uniform and decreased with the increase of plastic strain in localized band. Total strain of the specimen was decomposed into elastic and plastic parts. Plastic strain of the specimen was the average value of plastic strains in localized band over the entire specimen. For different heights, the predicted softening branches of the relative stressstrain curves in uniaxial compression are consistent with the previously experimental results for normal concrete specimens. The present expressions for the post-peak stressdeformation curves in uniaxial tension and direct shear agree with the previously numerical results based on gradient-dependent plasticity.展开更多
The solubility of ammonia in ethylene glycol is measured by an isothermal solubility equilibrium method at temperatures of （303.2, 308.2, 313.2, 318.2 and 323.2） K and total pressures of （0.030, 0.040, 0.050, 0.060...The solubility of ammonia in ethylene glycol is measured by an isothermal solubility equilibrium method at temperatures of （303.2, 308.2, 313.2, 318.2 and 323.2） K and total pressures of （0.030, 0.040, 0.050, 0.060, 0.070, 0.080, 9.090 and 0.101） MPa. The molality of ammonia in ethylene glycol ranges from 1.925 mol·kg-1 to 8.265 mol·kg-1. The experimental results are used to determine Henry＇s law constant of ammonia in ethylene glycol Furthermore, experimental data are correlated by applying the thermodynamic model on the basis of extended Raoult＇s law, extended Henry＇s law, corresponding-states correlations and Pitzer＇s molality scale based equation. The overall average relative deviation between the calculated data and the experimental data of Henry＇s law constant and ammonia solubility are 2.029% and 2.164% respectively.展开更多
In the present study, the flow visualizations were performed around the NACA 0012 models which differ in aspect ratios. We discussed the effects of the aspect ratio in the test models. Additionally the unsteady, two-d...In the present study, the flow visualizations were performed around the NACA 0012 models which differ in aspect ratios. We discussed the effects of the aspect ratio in the test models. Additionally the unsteady, two-dimensional, compressible Euler equations were solved for the NACA 0012 airfoil. Experiments were performed utilizing the conventional gas driven shock tube as the intermittent transonic wind tunnel. The aspect ratios of the models are about 0.86 and 1.5, respectively. The Mach numbers M 2 are about 0.84. The Reynolds numbers of the present experimental conditions were constant that Re based on chord length is about 4.0×10 5 . The results are as follows: in different aspect ratios, the difference of the shock wave location is confirmed though the Mach number and Reynolds number are same. It indicates the different correction Mach number by the effects of the side wall boundary layer though the nominal Mach number measured the same value. Also, on the difference of shock wave location for the effects of the aspect ratio, the tend of CFD shows the qualitative agreement with the result of an experiment.展开更多
文摘Considering strain localization in the form of a narrow band initiated just at peak stress, three analytical expressions for stressstrain curves of quasibrittle geomaterial (such as rock and concrete) in uniaxial tension, direct shear and uniaxial compression were presented, respectively. The three derived stressstrain curves were generalized as a unified formula. Beyond the onset of strain localization, a linear strain-softening constitutive relation for localized band was assigned. The size of the band was controlled by internal or characteristic length according to gradient-dependent plasticity. Elastic strain within the entire specimen was assumed to be uniform and decreased with the increase of plastic strain in localized band. Total strain of the specimen was decomposed into elastic and plastic parts. Plastic strain of the specimen was the average value of plastic strains in localized band over the entire specimen. For different heights, the predicted softening branches of the relative stressstrain curves in uniaxial compression are consistent with the previously experimental results for normal concrete specimens. The present expressions for the post-peak stressdeformation curves in uniaxial tension and direct shear agree with the previously numerical results based on gradient-dependent plasticity.
基金Supported by the National Natural Science Foundation of China(21176189)the Natural Science Foundation of Tianjin City(11JCZDJC24300)
文摘The solubility of ammonia in ethylene glycol is measured by an isothermal solubility equilibrium method at temperatures of （303.2, 308.2, 313.2, 318.2 and 323.2） K and total pressures of （0.030, 0.040, 0.050, 0.060, 0.070, 0.080, 9.090 and 0.101） MPa. The molality of ammonia in ethylene glycol ranges from 1.925 mol·kg-1 to 8.265 mol·kg-1. The experimental results are used to determine Henry＇s law constant of ammonia in ethylene glycol Furthermore, experimental data are correlated by applying the thermodynamic model on the basis of extended Raoult＇s law, extended Henry＇s law, corresponding-states correlations and Pitzer＇s molality scale based equation. The overall average relative deviation between the calculated data and the experimental data of Henry＇s law constant and ammonia solubility are 2.029% and 2.164% respectively.
文摘In the present study, the flow visualizations were performed around the NACA 0012 models which differ in aspect ratios. We discussed the effects of the aspect ratio in the test models. Additionally the unsteady, two-dimensional, compressible Euler equations were solved for the NACA 0012 airfoil. Experiments were performed utilizing the conventional gas driven shock tube as the intermittent transonic wind tunnel. The aspect ratios of the models are about 0.86 and 1.5, respectively. The Mach numbers M 2 are about 0.84. The Reynolds numbers of the present experimental conditions were constant that Re based on chord length is about 4.0×10 5 . The results are as follows: in different aspect ratios, the difference of the shock wave location is confirmed though the Mach number and Reynolds number are same. It indicates the different correction Mach number by the effects of the side wall boundary layer though the nominal Mach number measured the same value. Also, on the difference of shock wave location for the effects of the aspect ratio, the tend of CFD shows the qualitative agreement with the result of an experiment.
