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[en] This thesis deals with the short wavelength collective dynamics of dense binary fluid mixtures. The analysis shows that at the level of linearized generalized hydrodynamics, the longitudinal modes of the system separates essentially into two parts - one involves the coupling of partial density fluctuations of the two species and the other involves coupling of longitudinal momentum and temperature fluctuations. The authors have shown that the coupling of longitudinal momentum and temperature fluctuations leads to an adequate description of sound propagation in such systems. In particular, they show that structural disorder controls the trapping of sound waves in dense mixtures. The coupling of the partial density fluctuations of the two species leads to a simple description of the partial dynamic structure factors. The results are in agreement with the molecular dynamics simulations of soft sphere mixtures. The partial density fluctuations are the slowest decaying fluctuations on molecular length scales and it turns out that nonlinear coupling of these slow modes leads to important corrections to the long time behavior of the time correlation functions determining the shear viscosity in dense mixtures
[en] In this paper we describe the flow around two-dimensional circular cylinder bundles supported by wires. The experiment was carried out in an N.P.L. blow-down wind-tunnel with a 500 mm x 500 mm x 2000 mm working section, and with Reynolds number 9.4 x 103. The displacement of a vibrating circular cylinder, and the fluctuating pressure distributions on the surface of the circular cylinder were measured. It was found that (i) the critical value of the fluid elastic vibration occurring is obtained as the spacing ratio D/S for a single row, two rows and three rows, (ii) the fluctuating pressure distribution on the surface, fluctuating drag and fluctuating lift by natural frequency increase rapidly beyond the critical value mentioned in (i), and (iii) the variation of fluctuating drag and fluctuating lift corresponds to that of the displacement of a vibrating cylinder. (author)
[en] The safety factor determined on the basis of time to rupture calculation is applicable to the engineering design under creep condition. In this calculation, it is assumed that load remains constant within exploitation time. If not, the question arises how much safety factor is reduced from that calculated with respect to laod due to the material deterioration process developed under creep condition. It is necessary to distinguish between two safety factors: that connected with time to rupture and another connected with load. If a structure as a whole is considered, three periods of the failure process have to be distinguished: the time to the first macroscopic failure, the time when a deteriorated surface crosses a section of a structure, and finally the time when the structure collapses because of the formation of a brittle hinge. In this paper, the analysis of all the above factors is given consecutively. The analysis based on the Kachanov theory of damage growth and the modified damage theory in the safety factor for materials, and the general assumption, the governing equations and an example of a structure analysis in the safety factor for structures are explained. The most important factor affecting structure behavior is the redistribution of bending moment and stress. (K.I.)
[en] The automation technology of magnetic pulsed compaction (MPC) has been developed for mass production of high performance powder products by dynamic compaction method. The pulse power equipment in MPC system has been modified for improved lifetime and productivity, so the modified one can produce high-density compacts at a rate of 10 times/min with semipermanent lifetime. Using this modified pulse power equipment, two types of automated MPC apparatus were constructed, which are operated by mechanical and hydraulic driving systems, respectively. By repeated compaction operations at a rate of 5 times/min, durability and productivity of these automated apparatus have been proven to be suitable for mass production. In addition, the lifetime of mold and punch for MPC has been improved by optimizing design and material as well as employing new lubrication system. By applying such automated MPC apparatus, detailed mass production technologies have been developed for several powder products such as diamond drilling segments, ceramic targets for optical coating, silver coins for water disinfection and small powder products for automobile. The developed powder products showed improved performance as compared to commercial ones, so they will be mass-produced industrially before long
[en] Previously developed constitutive models and solution algorithms for anisotropic elastoplastic material strength are implemented in the two-dimensional MESA hydrodynamics code. Quadratic yield functions fitted from polycrystal simulations for a metallic hexagonal-close-packed structure are utilized. An associative flow strength formulation incorporating these yield functions is solved using a geometric normal return method. A stretching rod problem is selected to investigate the effects of material anisotropy on a tensile plastic instability (necking). The rod necking rate and topology are compared for MESA simulations performed for both isotropic and anisotropic cases utilizing the Mechanical Threshold Stress flow stress model. (orig.)
[en] Complete text of publication follows. The results of the investigations in the shock compressibility of materials on the 'Luch' facility are presented. The experiments have been performed with impedance mismatch technique applying. The output non-uniformity of the shocks achieved < 10 ps and inaccuracy of their velocity measuring < 3%. The pressures to 30 Mbars were developed in lead and till 50 Mbars with applying of the special-constructed targets for hydrodynamic pressure increasing. Results on the materials shock compressibility have been obtained that accord well with the test results shown on hydrodynamic stands. The work was performed in part under the sponsorship of the RFFI (grants No. 09-02-12157-ofi-m and No. 09-02-97089-r povolzh'ye-a), and grant of the President of the RF to leading scientific schools No. 65192.2010.2.
[en] Highlights: • The Link-Wise Artificial Compressibility Method (LW-ACM) is presented and evaluated. • The method is applied to attached and separated flows around airfoils at low speed and high AOA. • Investigations of the flow around NACA 0012 and TSAGI 12% airfoils are performed by using LW-ACM. • The LW-ACM is efficient and rapidly convergent when used to solve both attached and separated flows. - Abstract: The performance of the recently developed Link-Wise Artificial Compressibility Method (LW-ACM) is evaluated for aerodynamic applications and then applied for both attached and separated flows. Numerical flow simulations are performed around NACA-0012 and TSAGI-12 shaped airfoils at low speed and high angle of attack. Results of aerodynamic characteristics of the airfoils were found in good agreements with previous investigations including LBM (PowerFLOW) and FVM (CFL3D). Results also showed that LW-ACM is efficient and rapidly convergent when used to solve both attached and separated flows.
[en] A hydrodynamic model of super-deep penetration (SDP) effect based on the idea of a high-speed dense powder flux energy re-distribution during the time of the effect realization is being developed. Proposed model allows one to obtain a precise solution of the equation of motion for penetrating with the SDP mechanism cylindrical particle and to estimate main characteristics of the process which were found in a very good agreement with an experimental data. (orig.)
[en] One of reliability measurements of vehicle is estimated by driving mileage but the reliability of component, such as an hydraulic clutch system, is defined from the number of successful operational cycle. Relationship between these reliability measurement variables(mileage and cycle) should be examined first of all in the reliability estimation of components. Relationship between mileage and cycles is commonly known as linear function. However, the gradient depends on the operational environmental condition. Therefore, estimation of mission profile variable should be done with correlation analysis at the same time. In this paper, we derive mission profile variable of an hydraulic clutch system by field vehicle test and suggest the determination process of durability test parameters of CMC(Clutch Master Cylinder) with mission profile variable
[en] Since the beginning of aviation and up to the present time, airfoils have always been built as rigid structures. They are designed to fly under their divergence speed in order to avoid static aeroelastic instabilities and the resulting large deformations, which are not compatible with the typically low compliance of such airfoils. In recent years, research on airfoil morphing has generated interest in innovative ideas like the use of compliant systems, i.e. systems built to allow for large deformations without failure, in airfoil construction. Such systems can operate in the neighborhood of divergence and take advantage of large aeroelastic servo-effects. This, in turn, allows compact, advanced actuators to control the airfoil's deformation and loads, and hence complement or even replace conventional flaps. In order to analyze and design such compliant, active aeroelastic structures a nonlinear approach to static aeroelasticity is needed, which takes into account the effect of large deformations on aerodynamics and structure. Such an analytical approach is presented in this paper and applied to a compliant passive airfoil as the preliminary step in the realization of a piezoelectrically driven, active aeroelastic airfoil. Wind tunnel test results are also presented and compared with the analytic prediction. The good agreement and the observed behavior in the wind tunnel give confidence in the potential of this innovative idea