Isothermal vapour-liquid equilibrium data for the difluoromethane (R32)-1,1,1,2,3,3,3-Heptafluoropropane (R227ea) binary system are presented at 283.20, 303.21, 323.21 and 343.38 K and pressures up to 4.5 MPa. The experimental method, used for this work, is of the static-analytic type. It takes advantage of mobile pneumatic capillary samplers (Rolsi TM , Armines' patent) developed in our laboratory. The four P, x, y isothermal data have been represented with the Soave-Redlich-Kwong (SRK) equation of state and the MHV1 rules involving the NRTL model.
A ballistic projectile launching device was used to study the penetration behaviors of tungsten alloy spherical fragments of various diameters into carbon fiber composite target plates of different thicknesses. Based on the ballistic test results, we obtained the relationship between ultimate penetration velocity, target plate thickness, and fragment diameter as well as the relationship between the fragment penetration energy and fragment incident velocity. Using dimensional analysis, we obtained a formula relating the incident fragment velocity and the fragment penetration energy, which showed good agreement with the experimental values. We also analyzed the main fracture mode and the energy absorption mechanism of the carbon composite target plate under high-velocity impacts of tungsten alloy spheres and investigated the experimental damage modes of the target plate at different fragment velocities during the ballistic impact.
Poor compression in the strain clamp often makes the strands overheat and fracture. There exists a certain gap between conductors and the strain clamp if the strain clamp is compressed poorly. The ashes, oxide, corrosion and abrasion tend to gather and scale in the gap, forming scale layers of high resistivity. As the exposure time increases, the layers expand and thicken, which causes the worsening of conductive properties of current and heat, and leads to abnormal temperature elevation, the degradation of microstructure and properties and strands fracture at last. In consideration of this kind of strands fracture phenomenon and through FEM, non-uniform temperature field influenced by scale layer in the clamp has been analyzed and the quantitative relationship between the scale layer, peak temperature and current has been obtained. The results of material experiments show that the strands vary from each other in the roundness of shear lips. Serious erosion is found on the surface of outer Al (aluminum) strands attaching to the clamp, while there is almost no erosion mark on the surface attaching to inner Al strands. Erosion spots in Al strands surface attaching to the scale layer are the deepest, and each erosion pit is large and some of which have even developed into plaques. The interacting deterioration of scale and temperature causes the Al strands attaching to the scale layer to fail and then led to fracture-temperature domino effect of other strands. The longitudinal fibrous microstructure of steel strands disappeared as the temperature rose. The plasticity of strands increased after recovery and recrystallization. The rapid degradation of mechanics properties resulted in the drop accident of conductors.
The objective of this study was to study the penetration characteristics of tungsten alloy fragments on PCrNi3MoV target plates. Specifically, the penetration of square tungsten alloy fragments of gun steel target plates of different thicknesses were studied using a ballistic gun launching device. Based on the ballistic test results, the relationship between the bulge height of the target plate and the kinetic energy of the fragments was obtained, and the failure mode and process of the tungsten alloy fragments penetrating the steel target were analyzed. Then, the variation on the bulge height of the target plate with the kinetic energy of the fragments was obtained using dimensional analysis. The prediction results were consistent with the test results, and thus, the prediction model can be used in practical applications.
Taking a start-up separator of 600 MW supercritical boiler as the study object, analyse the stress field of it during the process of load pick-up with the three-dimensional finite element analysis method. In the analytical process, it has calculated the thermal stress, mechanical stress and the total stress of them, and analysed the change rules of them, so it provide the guidance of the production operation processes. The calculation results show that: the thermal stress of open pore on start-up separator exists obvious stress concentration phenomenon; The stress concentration of the total stress occurred in the oval long axis of cylinder body wall, where is the danger point of the start-up separator.
The anti penetration characteristics of natural rubber and the influence of fragment velocity on penetration energy were studied. Through the experimental study, the ultimate penetration velocity of different diameter fragments penetrating different thickness rubber target is obtained, and the penetration process is analyzed. The damage characteristics of target are explained through different stages of penetration. At the same time, the influence law of different residual velocity on the expansion velocity of rubber fragment cloud behind target is obtained, the energy required for the fragments to penetrate the target and the expansion velocity of the fragments after the target will increase with the increase of the fragments’ entry velocity.
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