Materials physics and mechanics

RAR RUS 1-6 Machine Dynamics and Vibrations Laboratory, Mechanical Engineering Discipline Agrawal

India

Machine Dynamics and Vibrations Laboratory, Mechanical Engineering Discipline Gupta

India

Machine Dynamics and Vibrations Laboratory, Mechanical Engineering Discipline Kankar

India

Study of horn shape double single walled carbon nanotube system via modified couple stress theory In the modern biomedical era of developing nanodevices particularly for the disease detection, fast and precise response is appreciated. Horn shaped double single walled carbon nanotube system (DSWNTS) possess excellent sensing characteristics due to better adsorbing effect. The work here focuses on determination of natural frequency of cantilever type horn shape DSWNTS. As it is already proven fact that such a type is less fragile and more sensitive, noticing its mechanical behavior is the need of time. Here, governing equation of motion pertaining to the dynamic analysis is developed by applying modified couple stress theory using variational principle. The natural frequency is determined and compared with the same of classical theory. The size effect is also discussed. The frequency ratio is more in case of modified couple stress theory particularly with less size effect. This work will be useful in design of low dimension structure for vibration isolation or for mechanical biosensor. 10.18720/MPM.3712018_1 DSWNTS; CNT; variational principle; MCST; horn shape https://mpm.spbstu.ru/article/2018.61.1/ MPM137_01_agrawal.pdf

RAR RUS 7-15 Manipal University Jaipur Dikshit

Jaipur, India

KJCEMR Engle

Maharashtra, India

Investigation of mechanical properties of CNT reinforced epoxy nanocomposite: a molecular dynamic simulations In the present research, MD simulations have been employed to study the mechanical properties of epoxy DGEBA with and without reinforcement of CNT. A triangular cross link rigid structure has been created using Material Studio (MS) software. An amorphous cell has been created which is a reprensentative composite. All the simulations have been carried out using Forcite module of Material Studio. Mechanical properties with and without reinforcement of CNT have been obtained. It has been found that at room temperature, Young’s modulus of DGEBA-DETDA composite is 2.429 GPa while after reinforcement of CNT, Young’s modulus increased to 13.27 GPa. The MD simulation results indicate that the Young’s modulus of the reinforced composites and the epoxy matrix decrease with increase in strain rate (from 0.0 to 0.1). MD simulation results show that at any given strain rate, CNT reinforced epoxy composite is 5 times stiffer than the pure epoxy matrix 10.18720/MPM.3712018_2 carbon nanotube; DGEBA; epoxy; molecular dynamics https://mpm.spbstu.ru/article/2018.61.2/ MPM137_02_dikshit.pdf

RAR RUS 16-24 Southern Federal University Kudimova

Rostov-on-Don, Russia

Southern Federal University Nadolin

Rostov-on-Don, Russia

Southern Federal University Nasedkin

Rostov-on-Don, Russia

Southern Federal University Nasedkina

Rostov-on-Don, Russia

Southern Federal University Oganesyan

Rostov-on-Don, Russia

Southern Federal University Soloviev

Rostov-on-Don, Russia

Models of porous piezocomposites with 3-3 connectivity type in ACELAN finite element package The work deals with the methods for solving homogenization problems for porous piezoceramic media with open porosity, which are implemented in ACELAN-COMPOS finite element software package developed by the authors. Determination of the effective properties of composite media is based on the effective moduli method and the finite element method. Special algorithm was developed to generate representative volumes for two-phase composites that support connectivity for both phases. The work of the suggested algorithm is illustrated by an example of porous piezoceramic PZT-4. Numerical experiments show that the representative volume structure can have a significant effect on the effective moduli of a piezoceramic with open porosity. 10.18720/MPM.3712018_3 piezoelectricity; 3-3 two-phase piezocomposite; effective moduli; representative volume; finite element method; finite element software https://mpm.spbstu.ru/article/2018.61.3/ MPM137_03_kudimova.pdf

RAR RUS 25-33 Southern Federal University Kudimova

Rostov-on-Don, Russia

Southern Federal University Nadolin

Rostov-on-Don, Russia

Southern Federal University Nasedkin

Rostov-on-Don, Russia

Southern Federal University Oganesyan

Rostov-on-Don, Russia

Southern Federal University Soloviev

Rostov-on-Don, Russia

Finite element homogenization models of bulk mixed piezocomposites with granular elastic inclusions in ACELAN package The paper presents the methods for solving the homogenization problems for two-phase piezoelectric composites, which are implemented in ACELAN-COMPOS finite element package, developed by the authors. The considered composites consist of piezoelectric skeleton and elastic inclusions. The effective moduli method is used to determine the effective properties of the composite. In this method, the static electroelasticity problems with special boundary conditions are set for a representative volume of the composite. These problems are solved numerically using the finite element method. The developed algorithm for generating representative volumes for the composites with granular inclusions is described in details. The work of the algorithm is illustrated by an example of a composite made of PZT-4 piezoceramic with inclusions of α-corundum. 10.18720/MPM.3712018_4 piezoelectricity; two-phase piezocomposite; effective moduli; representative volume; finite element method; f inite element software https://mpm.spbstu.ru/article/2018.61.4/ MPM137_04_kudimova.pdf

RAR RUS 34-41 Southern Federal University Nasedkina

Rostov-on-Don, Russia

Indian Institute of Technology Rajagopal

Hyderabad, India

Mathematical and computer homogenization models for bulk mixture composite materials with imperfect interfaces The paper describes the homogenization procedure for two-phase mixture elastic composites that consist of two isotropic phases. It is assumed that on the boundary between the phases, special interface boundary conditions are held, where the stress jumps over the interphase boundary are equal to the surface stresses at the interface. Such boundary conditions are used for description of nanoscale effects in elastic nanobodies and nanocomposites. The homogenization problems are solved using the approach of the effective moduli method, the finite element method and the algorithm for generating the representative volume that consists of cubic finite elements with random distribution of element material properties. To provide a numerical example, a wolfram-copper composite is considered, where the interface conditions are modeled by surface membrane elements. 10.18720/MPM.3712018_5 composite materials; homogenization problems; effective moduli method; finite element method https://mpm.spbstu.ru/article/2018.61.5/ MPM137_05_nasedkina.pdf

RAR RUS 42-51 Kuban State University Eremin

Krasnodar, Russia

Viscosity-driven attenuation of elastic guided waves in layered composite structures Along with the amplitude and dispersion directivity, conditioned by the material anisotropy, source-induced elastic guided waves in layered fiber-reinforced polymercomposite structures exhibit non-neglectable attenuation due to the polymer matrix viscosity. The latter should be adequately accounted for in ultrasonic nondestructive testing and structural health monitoring systems for their reliable operation. In the current paper, the influence of attenuation on guided wave propagation in anisotropic laminates is investigatedexperimentally and numerically. In the computational model, viscosity driven wave amplitudedecay is addressed through the complex stiffness matrix, and semi-analytical integral approach is employed for parametric analysis. Experimental measurements are performed for piezoelectrically excited guided waves with scanning laser Doppler vibrometry technique. 10.18720/MPM.3712018_6 elastic guided waves; laminate composites; attenuation; linear viscoelasticity https://mpm.spbstu.ru/article/2018.61.6/ MPM137_06_eremin.pdf

RAR RUS 52-59 Kuban State University Golub

Krasnodar, Russia

Kuban State University Doroshenko

Krasnodar, Russia

Chalmers University of Technology Boström

Göteborg, Sweden

Transmission of elastic waves through an interface between dissimilar media with random and periodic distributions of strip-like micro-cracks The present work investigates wave propagation through a damaged interface between two elastic media. Dynamic behaviour of the deterioration or damage of an interface is described using a random distribution of strip-like micro-cracks of different sizes, a periodic array of strip-like cracks or via a distributed spring model. The wave-field scattered by cracks is calculated using a boundary integral equation method. The spring model assumes introduction of the spring boundary conditions, where stresses are proportional to the displacement jump with the proportionality given by the spring stiffness. Components of the spring stiffness matrix are defined in terms of the concentration of the defects, their typical size and the elastic properties of the contacting materials. Numerical analysis of reflection and transmission for the considered models of the damaged interface is provided. 10.18720/MPM.3712018_7 imperfect contact; crack; interface; spring model; elastic wave; periodic array; random distritution https://mpm.spbstu.ru/article/2018.61.7/ MPM137_07_golub.pdf

RAR RUS 60-66 Southern Federal University Boyev

Rostov-on-Don, Russia

Application of the ultrasonic waves for detection of exfoliations between the solid inclusions and the elastic matrix of a metamaterial There is developed an algorithm to determine position of possible exfoliations of a triple-periodic system of elastic inclusions from an elastic matrix of a metamaterial after its production. For this aim there is used the irradiation of each side of a cubic specimen of the metamaterial by short impulses with a tone filling with the ultrasonic longitudinal waves. The algorithm implies the experimental and the theoretical study of the propagation of a high-frequency wave through the periodic system of inclusions. The theoretical solution is constructed by methods of the geometrical diffraction theory. Based on comparison of the experimental data and the theoretical calculations there is evaluated the presence of exfoliations and their position inside the metamaterial. 10.18720/MPM.3712018_8 metamaterials; elastic wave propagation; elastic medium with spherical inclusions; geometrical diffraction theory https://mpm.spbstu.ru/article/2018.61.8/ MPM137_08_boyev.pdf

RAR RUS 67-72 Southern Federal University Gusev

Rostov-on-Don, Russia

Southern Federal University J.Y. Jityaeva

Rostov-on-Don, Russia

Southern Federal University Ageev

Rostov-on-Don, Russia

Effect of PECVD conditions on mechanical stress of silicon films In the work, silicon films were obtained from SiH4 by plasma-enhanced chemical vapors deposition. The influence of deposition temperature (200 – 650°C) and gas mixture pressure (500 – 2000 mTorr, Ar/SiH4) on the mechanical stresses in the films were studied by stylus profilometry and curvature method. Mechanical stresses in films with thickness changing from 270 nm to 1.93 μm are in the range of −750 to +250 MPa. The deposition rates were 7 – 46 nm/min irrespective of temperature at 500 mTorr. Temperature dependences had inflection close to 450°C. Low-stressed (tensile and compressive) and stress-free films can be formed and qualified for solar cells fabrication, based on textured silicon, glass or flexible substrates as well as for micro- and nanomechanics, particularly relatively thick films of 1 – 2 μm, obtained at 2000 mTorr and rates about of 50 nm/min. 10.18720/MPM.3712018_9 mechanical stress; silicon film; SiOx; PECVD; profilometry https://mpm.spbstu.ru/article/2018.61.9/ MPM137_09_gusev.pdf

RAR RUS 73-78 Lobachevsky State University of Nizhni Novgorod Igumnov

Nizhni Novgorod, Russia

Lobachevsky State University of Nizhni Novgorod Belov

Nizhni Novgorod, Russia

Lobachevsky State University of Nizhni Novgorod Ipatov

Nizhni Novgorod, Russia

Results of computer modelling of a composite poroviscoelastic prismatic solid dynamics Boundary-value problems for piecewise homogeneous solids in terms of linear three-dimensional poroviscoelasticity are considered. Mathematical model of poroviscoelastic material is based on Biot's model of poroelasticity. Viscoelastic effects refer to a skeleton of porous material and are described through the correspondence principle. Standard linear solid model is employed. Viscosity parameter influence on dynamic responses of displacements, pore pressure and tractions is studied. In order to study the boundary-value problem boundary integral equations (BIEs) method is applied, and to find their solutions boundary element method (BEM) for obtaining numerical solutions is used. The numerical scheme is based on the Green-Betty-Somilliana formula. The solution of the original problem is constructed in Laplace transforms, with the subsequent application of the algorithm for numerical inversion. Modified Durbin’s algorithm of numerical inversion of Laplace transform is applied to perform solution in time domain. The problem a poroviscoelastic prismatic solid clamped from one end and free at another is considered. The solid is composed of two subdomains. Heaviside-type load is applied to a free end of the solid. Numerical results for displacements and pore pressure, when subdomains are modelled with different viscoelastic properties, are presented. 10.18720/MPM.3712018_10 poroviscoelasticity; viscoelastic models; boundary element method; boundary integral equation; Laplace transform https://mpm.spbstu.ru/article/2018.61.10/ MPM137_10_igumnov.pdf

RAR RUS 79-83 Lobachevsky State University of Nizhni Novgorod Igumnov

Nizhni Novgorod, Russia

Lobachevsky State University of Nizhni Novgorod Markov

Nizhni Novgorod, Russia

A boundary element approach for 3D transient dynamic problems of moderately thick multilayered anisotropic elastic composite plates A Laplace-domain boundary element approach for transient dynamic analysis of three-dimensional (3D) moderately thick multilayered (piecewise homogeneous) anisotropic linear elastic composite plates is presented. The boundary element formulation is based on the system of weakly singular displacement boundary integral equations. The spatial discretization is based on collocation method and mixed representation of geometry and boundary functions. To obtain time-domain solutions, the Convolution Quadrature Method with the Runge-Kutta method as an underlying time stepping method is used as a numerical technique for inverse Laplace transform. To improve the computational efficiency of the boundary element formulation a parallelization scheme is implemented. Boundary element results for the test example are provided to validate the proposed approach. 10.18720/MPM.3712018_11 multilayered plates; anisotropic linear elasticity; boundary element method; dynamic analysis https://mpm.spbstu.ru/article/2018.61.11/ MPM137_11_igumnov.pdf

RAR RUS 84-91 Southern Federal University Zhuravlev

Rostov-on-Don, Russia

Southern Federal University Drobotov

Rostov-on-Don, Russia

Southern Federal University Piskunov

Rostov-on-Don, Russia

Don State Technical University Maksimets

Rostov-on-Don, Russia

The comparative evaluation of precision of classical and numerical solutions of contact problems It is shown that the true reason of existing inconsistency at comparison of the Hertz–Belyaev classical solutions of contact problems with the numerical solutions, obtained by finite element method ( FEM) for canonical-formed elastic bodies contact more often is not the unsubstantially declared poor precision of the numerical method, but the substantial distortion of the contact elements curvature, which causes accuracy of classical solutions. The criteria of reliable accuracy evaluation of classical and numerical solutions of contact problems at measuring the maximal shear stresses and the depth of its occurrence are given. 10.18720/MPM.3712018_12 depth of the maximal shear stress; elastic cylinders; contact mechanics; curvature; maximal contact stress; maximal shear stress https://mpm.spbstu.ru/article/2018.61.12/ MPM137_12_zhuravlev.pdf

RAR RUS 92-99 M.S. Ramaiah University of Applied Sciences Anil Kumar

Bengaluru, India

M.S. Ramaiah University of Applied Sciences Mahendra Babu

Bengaluru, India

Sequential cold expansion and resulting beneficial residual stress prediction around adjacent fastener holes Fatigue life of aircraft structure fastener holes are enhanced through cold expansion process, which creates an annular zone of compressive residual stresses around the hole. Durability and damage tolerance analysis of structures containing cold expanded adjacent holes require quantification of cold expansion-induced compressive residual stresses. Three-dimensional non-linear FE simulation of sequential cold expansion of two closely spaced adjacent holes in Al 7075-T651 plate is carried out to predict the beneficial residual stresses completely. Further, an experimental investigation on sequential cold expansion of adjacent holes is carried out using cold expansion tooling system developed in-house and the retained expansion levels are measured. Comparison of FE simulation results and results of experimental investigations indicate that developed simplified FE simulation approach is capable of adequately predicting cold expansion-induced beneficial residual stresses around the hole, including through thickness variations. 10.18720/MPM.3712018_13 fatigue life; adjacent fastener holes; cold expansion; compressive residual stress https://mpm.spbstu.ru/article/2018.61.13/ MPM137_13_kumar.pdf

RAR RUS 100-103 Novorossiysk Branch of Belgorod State Technological University named after V. G. Shukhov Mkrtychev

Novorossiysk, Russia

Temperature field of the irradiated material in the laser-induced damage The use of powerful pulse lasers in various areas of science and technology requires an understanding of the physical mechanisms of laser-induced damage to the irradiated substance. In this paper, we consider the numerical solution of the one-dimensional non-stationary heat equation. The developed algorithm of the solution and the software, created with this application using a specialized application software package, allowed one to analyze the dynamics of a number of parameters of laser ablation destruction. It is possible take into account the differences and make calculations, based on the developed computer program for parameters, which can depend on time and coordinates in an arbitrary way. As the most significant application, one can point out the approximations of the solutions obtained for the sub-threshold radiation conditions. 10.18720/MPM.3712018_14 laser-induced damage; laser ablation; method of moments https://mpm.spbstu.ru/article/2018.61.14/ MPM137_14_mkrtychev.pdf

RAR RUS 104-108 17 Agustus 1945 University Surabaya Witjaksana

Surabaya, Indonesia

Additional steel fibers in concrete mixture: studies of compressive and tensile strength of concrete Test results for average compressive strength of 200.81 kgF/cm2 were obtained for 3-day age of concrete at the fraction of steel fibers equal to 2.5%; for 7-days concrete we obtained the corresponding value of 263.97 kgF/cm2 at the fraction of steel fibers equal to 2.5%; for 14-day concrete this value was 183.84 kgF/cm2 at the fraction of steel fibers of 7.5%; and for 21-day concrete the average compressive strength of 345.99 kgF/cm2 was attained at the fraction of steel fibers of 7.5% steels. Test results for average tensile strength of 40.46 kgF/cm2 were obtained for 3-day age of concrete at the fraction of steel fibers equal to 2.5%; for 7-days concrete we obtained the corresponding value of 48.95 kgF/cm2 at the fraction of steel fibers equal to 2.5%; for 14-day concrete this value was 54.38 kgF/cm2 at the fraction of steel fibers of 5%; and for 21-day concrete the average compressive strength of 56.27 kgF/cm2 was attained at the fraction of steel fibers of 7.5% steels. 10.18720/MPM.3712018_15 steel fibers; concrete mixture; compressive and tensile strength https://mpm.spbstu.ru/article/2018.61.15/ MPM137_15_witjaksana.pdf