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Journal of Applied Mechanics and Technical Physics

2022 year, number 2

Shaping of a Free Jet of Overheated Water at Different Distances from a Cylindrical Channel

K. A. Busov, N. A. Mazheiko
Institute of Thermal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg, 620016, Russia
Keywords: superheated liquid, explosive boiling, atomization, jet angle, short nozzle

Abstract >>
This paper presents an experimental investigation of the dependence of the shape, structure, and opening angle of a water jet on the degree of superheating. The relationship between different boiling modes and characteristic shapes of a boiling jet has been revealed. It has been found that the shape and the opening angle of a superheated liquid jet under the same thermodynamic conditions change in different ways depending on the length of the jet. The changes in the opening angle of a boiling jet are presented in the meter, decimeter, and centimeter ranges.

Motion of a Sphere Submerged in Water with an Ice Cover under Nonuniform Compression

L. A. Tkacheva
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: thin elastic floating plate, flexural gravity waves, dipole, multipole, wave forces

Abstract >>
The problem of the motion of a sphere in an ideal incompressible infinite fluid depths under ice cover with nonuniform compression was solved using the method of multipole expansions within the framework of the linear potential theory of waves. researched The hydrodynamic loads acting on the body such as the wave resistance and the lateral and lift forces were studied, and the deflection of the ice cover was analyzed as a function of its thickness, body speed, and the depth of submersion and direction of motion.

Propagation of Oblique Flexural Gravity Waves over Finite Number of Steps

S. Paul1, S. De2
1Roy Engineering College, Durgapur-713206, India
2University of Calcutta, Kolkata-700009, India
Keywords: step bottom, flexural gravity wave, eigenfunction expansion, multiterm Galerkin's expansion, integral equations, reflection and transmission coefficients

Abstract >>
A linearized model is presented for the scattering problem of flexural gravity waves by the bottom with a finite number of rectangular steps in the ocean. The matched eigenfunction expansion method is used to solve the boundary-value problem, and the results are expressed in terms of a set of integral equations solved by the multiterm Galerkin's approximation technique. Numerical values of the reflection and transmission coefficients are calculated and graphed to display the influence of various parameters of the problem. The accuracy of the present method is verified by using the energy balance relation for the reflection and transmission coefficients. The results are compared with those available in some earlier works.

Mechanism of Bursting Formation in a Supersonic Gas Flow Past a Narrow Flat Plate

I. I. Lipatov, R. Ya. Tugazakov
Central Aerohydrodynamic Institute, Zhukovskii, 140180, Russia
Keywords: supersonic flow, laminar and turbulent flows, turbulent spots, bursting, resonant amplification of waves

Abstract >>
Theoretical results obtained within the framework of the weakly nonlinear model of a developed boundary layer in a flow past a narrow flat plate are verified with the use of methods of direct numerical simulation of the Navier-Stokes equations. The mechanism of gas ejection (bursting from the surface of a thermally insulated plate in a supersonic gas flow with the Mach number M = 2 is studied within the framework of the model of complete nonlinear interaction. It is demonstrated that the transition from the laminar to turbulent flow past the plate in the case of weak external perturbations occurs due to resonant three-wave interaction. Theoretical results relating the energy redistribution between the oscillations and the process of spatial structure formation are confirmed.

Current Spreading Across the Width of Thin Foils (in Snake-Like Systems) or Plane Current Sheets

S. F. Garanin, E. M. Kravets
All-Russian Research Institute of Experimental Physics, Sarov, 607188, Russia
Keywords: foil circuit breaker, current sheet, filamentation, tearing instability, current distribution relaxation

Abstract >>
The problem of current spreading across the width of thin foils (in snake-like systems) or planar current sheets is considered. For calculation the evolution of the current distribution across the width of inhomogeneous thin conductive layers or foils is calculated using an integrodifferential equation which reduces the two-dimensional problem for the magnetic field to a one-dimensional problem. An infinite periodic system of plane snake-like foils is considered. It is shown that in this foil system the current distribution corresponding to the ideal foil conductivity is first established and then relaxation of the current distribution to a uniform one occurs. If the foils are used as circuit breakers, current must have time to be distributed uniformly across the foil width during current transfer to the load, so that the corrections for the nonuniformity of the current distribution in the switches should be small.

Finite Element Modeling and Optimization of the Lumbar Interbody Cage Based on the Additive Manufacturing Method

P. Sadeghinia1, A. S. Roshan1, P. K. Goudarzi2, M. Nikkhoo1
1Islamic Azad University, Tehran, 1477893855, Iran
2AJA University of Medical Science, Tehran, 1411718541, Iran
Keywords: PLIF cage, additive manufacturing, design and optimization, finite element analysis, von Mises stress, porous structure, mechanical properties

Abstract >>
This study is aimed at designing, optimizing, and validating a posterior lumbar interbody cage (PLIF) model based on the 3D printing method, which provides patients with a suitable customized design capable of providing proper mechanical support. In the content of this study, the CATIA software is used for modeling of three symmetrical cage models with different porosities. Then, two replicates of each cage model are assembled in the disc space of a parametric geometry of the L1-L2 vertebrae. The proposed models are meshed, and a finite element analysis is conducted through compressive and moment loadings. The overall stiffness and von Mises stress and strain of each model are determined.

Numerical Design Study of Continuous Separation of Blood Cells in a Microfluidic Device using Combined Dielectrophoretic and Hydrodynamic Forces

S. Bahrami, M.S. Feali
Islamic Azad University, Kermanshah, Iran
Keywords: blood, separation, dielectrophoresis

Abstract >>
A new design for continuous separation of multiple blood cells from diluted whole blood in a microfluidic device based on dielectrophoresis phenomenon is presented. Compared to the other studies, the proposed separator is designed for simultaneous separation of more types of blood cells with desirable accuracy. Using finite-element-based simulations, the device efficiency is evaluated for separation of five blood cell types. The proposed separator uses both dielectrophoretic and hydrodynamic drag forces to separate blood cells. The separator performance under different operating conditions is also evaluated.

Strength Properties of Vessels of the Abdominal Aorta:Experimental Results and Perspectives

A. I. Lipovka1, A. A. Karpenko2,3, A. P. Chupakhin1, D. V. Parshin1
1Novosibirsk National Research State University, Novosibirsk, 630090, Russia
2Novosibirsk National Research State University, Novosibirsk, 630055, Russia
3Meshalkin National Medical Research
Keywords: abdominal aortic aneurysm, uniaxial mechanical test, ultimate strength characteristics, biomechanics, hydroelasticity

Abstract >>
Aorta is the largest vessel of the human circulatory system, which plays a critical role in the supply of oxygen and nutrients tp all organs of the abdominal cavity and lower limbs. The critical pathology of this vessel is aneurysm. In medical practice, an important problem is aortic aneurysm rupture prediction and surgery planning since aneurysm rupture outside the clinic, as a rule, leads to a lethal outcome. To construct adequate mathematical models that predict such an outcome, it is necessary to determine the strength characteristics of the tissues of the aorta itself, its aneurysm and iliac arteries at various stages of growth of such an aneurysm, and also taking into account patient data. The strength characteristics of tissues of the human aorta, its aneurysm, and iliac arteries have been studied. It has been experimentally proved that in samples of healthy aorta tissues, the differences between the values of the limiting relative deformations in the axial and tangential directions are statistically significant ( p = 0.033), which is not observed in the case of an aortic aneurysm. The results can also be interpreted as the fact of remodeling of the aortic aneurysm wall in comparison with the healthy aorta. These data can be used in personalized hydroelastic simulation during construction of predictive models for the rupture of such aneurysms.

Study of SH-Wave Propagation in an Initially Stressed Triclinic Layer Sandwiched between Transversely Isotropic Elastic and Heterogeneous Poroelastic Half-Spaces

P. Malla Reddy1, M. Venugopal2, G. Rajitha1
1Kakatiya University, Warangal, India
2Kakatiya Government College, Warangal, India
Keywords: SH-wave, triclinic layer, transversely isotropic half-space, inhomogeneity, poroelastic half-space, initial stress, porosity, phase velocity

Abstract >>
In this paper, SH-wave propagation in an initially stressed triclinic layer welded between two half-spaces is investigated. The upper half-space is considered to be transversely isotropic and elastic, while the lower one is heterogeneous, isotropic, and poroelastic. In the case of the lower half-space, the problem is reduced to the Whittaker differential equation. Frequency equations are derived for the layer as a whole and half-spaces. It is found that the phase velocity is strongly influenced by the initial stress, porosity, and heterogeneity.

Effect of Laser Action Parameters on the Formation of a Bath of the Molten B4C - Ti-6Al-4V Cermet Mixture

A. A. Golyshev, A. M. Orishich
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch,, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: laser cladding, CO laser, boron carbide, Ti-6Al-4V alloy, microstructure, microhardness, dimensionless parameters

Abstract >>
Results of a series of experiments aimed at studying laser cladding of individual tracks with the use of the B4C-Ti-6Al-4V cermet powder mixture are reported. The influence of laser cladding parameters (radiation power, beam motion velocity, and focus position) on the characteristics of tracks being formed (geometric sizes, microhardness, and elemental composition) is studied. It is shown that an increase in the concentration of reinforcing particles in the initial powder mixture alters the character of mass transfer inside the melt bath, leading to changes in the shape of the single track. It is found that a complex heterogeneous structure is formed in the melt bath, including secondary phase compounds formed in chemical reactions due to in-situ synthesis. The microhardness values at various points of the single track are observed to differ by more than a factor of 2 (in the interval HV0.3 = 548-1415).

Optimization of Cold Gas-Dynamic Spraying of Neutron-Absorbing Composite (Al + B4C) Coatings

S. V. Klinkov, V. F. Kosarev, V. S. Shikalov, T. M. Vidyuk
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: cold gas-dynamic spraying, deposition efficiency, content of ceramic component in coating

Abstract >>
The possibility of obtaining composite coatings from a mixture of aluminum and boron carbide powders for neutron shielding by cold gas-dynamic spraying has been studied. The dependences of the deposition efficiency and the residual content of boron carbide in the coating on its initial content in the sprayed mixture of powders were derived. The obtained regularities have been analyzed, and an approach has been proposed to search for the boron carbide concentration in the powder mixture that is optimal for creating effective neutron-absorbing coatings. It has been shown that the highest productivity of the spraying process is achieved when using the optimal powder composition with (a volume fraction of boron carbide of about 0.5).

Feasibility of the (4Оґt, Пѓ22c) Criterion to Predict Fracture Toughness of Ferritic Steel using Specified Specimen Types

J. Pan1,2, Y. Wang2
1Hefei University of Technology, Hefei, 230009, China
2State Key Laboratory of Nuclear Power Safety Monitoring Technology and Equipment, Shenzhen, Guangdong, 518172, China
Keywords: fracture toughness, finite element analysis, (4Оґ, Пѓ) criterion, constraint loss, scaling function

Abstract >>
An improved Ritchie-Knott-Rice failure criterion, namely (4δt, σ22c) criterion, for the A515-70 steel is studied with allowance for the specimen geometry, specimen temperature, and initial crack length. The results show that the (4δt, σ22c) criterion can effectively predict the cleavage fracture. Results of studying the possibility of using a dimensionless function for determining the fracture toughness are reported.

Simulation of Viscoelastoplastic Behavior of Shallow Shells with Account for Strain Rate of the Material

A. P. Yankovskii
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: viscoelasticity, theory of viscoelastic-viscoplastic deformation, flexible shallow shell, Ambartsumyan theory, explosive load, cross-type numerical scheme

Abstract >>
This paper describes a numerical-analytical model of the viscoelastic-plastic behavior of flexible shallow shells with account for the dependence of plastic properties of their materials on strain rate. The inelastic behavior of materials is described by the theory of flow with isotropic hardening. Loading functions depend on the hardening parameter and strain rate intensity. Viscoelastic behavior is described by linear constitutive equations from a multiconstant body model. Lateral shears of structures during bending deformation are taken into account within the framework of the Ambartsumyan theory, and geometric nonlinearity within the von Karman approximation. A cross-type explicit scheme is used for the numerical integration of the formulated initial boundary value problem. The dynamic deformation of a cylindrical elongated panel made of a polymer material is studied. The structure is transversely loaded by a pressure generated by an air blast wave. It is shown that neglecting the dependence between the plastic properties of the material and the strain rate may cause one to significantly underestimate the maximum deflection value in absolute value and the largest strain value during oscillations and cause one to overestimate a maximum residual strain. In addition, the diagrams of residual deflections of the structure obtained by such a calculation do not agree with the diagrams obtained by a calculation that takes the mentioned dependence into account.

Bending of Thin Electromagnetic Plates

S. A. Kaloerov, A. V. Seroshtanov
Donetsk National University, 83001, Donetsk, Russia
Keywords: theory of bending of thin plates, electromagnetoelasticity, complex potentials, series method, exact solutions, piezoelectric effect

Abstract >>
Main correlations in the theory of bending of thin electromagnetoelastic plates are obtained, in which complex potentials are used. Exact analytical solutions are obtained for the problems of bending an elliptical plate and an infinite plate with an elliptical hole. It is established that no electric or magnetic inductions arise in the case of a simply connected finite plate under mechanical influences, and no mechanical stresses arise under the action of inductions, despite the fact that the piezoelectric effect occurs due to deformations, displacements, and field potentials. The piezoelectric effect in the case of an infinite simply connected plate is always observed and has a significant effect on the values of bending moments. The influence of the physical and mechanical properties of materials and the geometric characteristics of holes on the values of bending moments In the case of a plate with an elliptical hole is studied.

Wear of Dry Friction Pairs Consisting of High-Carbon Chrome-Vanadium Steels and Hard Alloys

O. I. Stoyanovskii, V. G. Galutskii, D. I. Kotov
Design and Technology of the Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: wear resistance, dry friction, specific load, chromium, vanadium, carbides

Abstract >>
The wear resistance of DI37-VI and EK80-VI steel is studied using a device for investigating friction. A sample made of high-carbon chromium-vanadium steel relative to pellets of MS221, VK3M, and VK6OM hard alloys on this device carries out reciprocating motion at a rate of 0.1 m/s. The base friction path is 50 km and the average temperatures of the samples are 100, 140, and 190oC. The effect of an average temperature of samples on the wear resistance of DI37-VI and EK80-VI steel is described.

Study of Physical Properties of TiC-NiCr Ceramic-Metallic Compacts Obtained by Hot Pressing

A. E. Chesnokov, A. A. Filippov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
Keywords: hot pressing, titanium carbide, nickel-chromium alloy, hardness, microhardness, structural-phase composition

Abstract >>
This paper presents the results of an experimental study of the physical properties, microstructure, and phase composition of a TiC-NiCr ceramic-metallic compact obtained by hot pressing. It is shown that an increase in the volume fraction of the metal binder in the samples reduces the HRA hardness (from 55 to 25) and the HV300 microhardness (from 1000 to 350) of the material.

Influence of Laser Shock Hardening on Lowand High-Cycle Fatigue of a OT4-0 Titanium Alloy

E. A. Gachegova1, R. Sikhamov2, F. Fentske2, N. Kashaev2, O. A. Plekhov1
1Institute of Continuous Media Mechanics, Perm, 614013, Russia
2Institute of Mechanics of Materials of the Helmholtz Center in Gestacht, Gestacht, 21502, Germany
Keywords: laser shock hardening, OT4-0 titanium alloy, residual stresses, fatigue life

Abstract >>
Effect of laser shock hardening on the fatigue life of an OT4-0 titanium alloy is studied. Laser hardening is carried out using a fractionally modulated Nd:YAG laser operating at a pulse repetition rate of 10 Hz. It is suggested by the analysis of the effect of various laser treatment parameters on the magnitude and distribution of residual stresses over the sample thickness that an optimal type of laser shock treatment makes it possible to create a compressive residual stress region whose depth reaches up to 1 mm and whose maximum value is 600 MPa. It is shown by the results of studying the fracture surface structure that the fatigue fracture mechanism changes, while the service life of specimens significantly increases during both low- and high-cycle fatigue after laser shock hardening.

Plastic Instability for a Plastic Orthotropic Spherical Pressure Vessel under Internal Impulsive Loading

Y. C. Zhang, C. W. Jin, M. Pang
Zhejiang University, Hangzhou, 310058, China
Keywords: spherical pressure vessel, plastic instability, plastic orthotropy, impulsive loading, strain rate

Abstract >>
This paper describes an investigation of plastic instability of an internally impulsively loaded thin-walled spherical pressure vessel with plastic orthotropy. In the framework of finite deformation and Hill's orthogonal anisotropic yield criterion, the vessel instability strain is derived, which includes the effects of the plastic orthotropy and strain rate.

Study of Rheological Properties of Rocks in Experiments on Stepwise Loading of Cylindrical Samples

Yu. V. Osipov1, A. S. Voznesenskii2
1Gazprom Geotekhnologii Company, Moscow, 123290, Russia
2MISiS National Research Technological University, Moscow, 119991, Russia
Keywords: rheological properties of rocks, viscoelastic model, laboratory experiment, stepped loading, rock salt, bischofite

Abstract >>
A method for determining the empirical dependence of the rheological properties of rocks on stresses has been developed and tested in the laboratory. The results of tests of cylindrical samples of rock salt and bischofite of the Nizhnevolzhsky deposit were used to obtain strain curves under stepwise loading and develop and verified a viscoelastic model describing the change in strains over time. It has been shown that the parameters characterizing the elasticity and the viscosity of the studied rocks decrease with increasing stress. This corresponds to the successive transition from the stage of elastic deformation to the stage of decaying, steady-state, and progressive creep. It has been established that creep of bischofite manifests itself at stresses above 0.5 MPa, and the creep of rock salt at stresses above 5 MPa. In relation to the uniaxial compressive strength and maximum strains, the creep of bischofite manifests itself at a relative strain above 0.0013 and at a relative stress of 0.19, and for rock salt, these values exceed 0.11 and 0.43, respectively.

Investigation of Nonlinear Deformation and Stability of a Composite Shell under Pure Bending and Internal Pressure

L. P. Zheleznov, A. N. Ser'eznov
Chaplygin Siberian Scientific Research Institute of Aviation, Novosibirsk, 630051, Russia
Keywords: cylindrical composite shells, discrete reinforcements, nonlinear deformation, stability, finite element method

Abstract >>
The finite element method is used to obtain solutions to problems of strength and stability of reinforced cylindrical shells made of composite material with account for the momentum and nonlinearity of their subcritical stress-strain state. The stability of a reinforced aircraft fuselage compartment made of composite material is studied under pure bending and internal pressure loading. The effect of deformation nonlinearity, stringer stiffness, and shell thickness on critical loads at which shell buckling occurs is studied.

Experimental and Analytical Study of Geometric Nonlinear Bending of a Cantilever Beam under a Transverse Load

D. M. Zuev1, D. D. Makarov1, K. G. Okhotkin1,2
1Reshetnev Siberian State University of Sciences and Technology, Krasnoyarsk, 660037, Russia
2AO "Informatsionnye Sputnikovye Sistemy", Zheleznogorsk, 662972, Russia
Keywords: geometrically nonlinear bending, large deformations, experiment, cantilever beam, thin elastic rod

Abstract >>
Exact and approximate analytical solutions are compared with experimental data on the geometrically nonlinear bending of a thin elastic cantilever beam under the action of a transverse concentrated load at its free end.