Autor: Kumar, S. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Microstructural considerations on SH-wave propagation in a piezoelectric layered structure
Autorzy:: Goyal, R.
Kumar, S.
Powiązania:: https://bibliotekanauki.pl/articles/280348.pdf
Data publikacji:: 2018
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: SH-wave
piezoelectricity
couple stress
characteristic length
Opis:: Shear wave based acoustic devices are being used in gaseous and liquid environments because of their high-sensitivity. The theoretical study of horizontally polarized shear (SH) waves in a layered structure consisting of a piezoelectric ceramic of P ZT − 5H or BaT iO3 material overlying a couple stress substrate is presented in this paper. The considered substrate is supposed to be exhibiting microstructural properties. The closed form expression of dispersion relations are derived analytically for electrically open and short conditions. The effects of internal microstructures of the couple stress substrate, thickness of P ZT − 5H or BaT iO3 ceramic, piezoelectric and dielectric constants are illustrated graphically on the phase velocity of the piezoelectric layer under electrically open and short conditions.
Źródło:: Journal of Theoretical and Applied Mechanics; 2018, 56, 4; 993-1004
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Dispersion of SH waves in a viscoelastic layer imperfectly bonded with a couple stress substrate
Autorzy:: Sharma, V.
Kumar, S.
Powiązania:: https://bibliotekanauki.pl/articles/949130.pdf
Data publikacji:: 2017
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: SH waves
couple stress theory
imperfect bonding
characteristic length
viscoelasticity
Opis:: The paper deals with propagation of SH waves in a viscoelastic layer over a couple stress substrate with imperfect bonding at the interface. A dispersion equation of SH waves in a viscoelastic layer overlying the couple stress substrate with an imperfect interface between them has been obtained. Dispersion equations for propagation of SH waves with perfectly bonded interface and slippage interface between two media are also obtained as particular cases. Effects of the degree of imperfectness of the interface are studied on the phase velocity of SH waves. The dispersion curves are plotted and the effects of material properties of both couple stress substrate and viscoelastic layer are studied. The effects of internal microstructures of the couple stress substrate in terms of characteristic length of the material are presented. The effects of heterogeneity, friction parameter and thickness of the viscoelastic layer are also studied on the propagation of SH waves.
Źródło:: Journal of Theoretical and Applied Mechanics; 2017, 55, 2; 535-546
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Effects of liquid loadings on lamb waves in context of size dependent couple stress theory
Autorzy:: Sharma, V.
Kumar, S.
Powiązania:: https://bibliotekanauki.pl/articles/949331.pdf
Data publikacji:: 2015
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: couple stress
characteristic length
Lamb waves
elastic waves
liquid loadings
Opis:: For understanding the effects of an internal microstructure, generalised microcontinuum theories with additional microstructural parameters are developed. One such a parameter, called the characteristic length of the material comparable with the internal cell size of the material is involved in the couple stress theory. The problem of propagation of Lamb waves in a plate with an internal microstructure and loaded with an inviscid liquid on both sides is studied using the couple stress theory. The dispersion equation of Lamb waves with the liquid loadings is derived. The impact of the liquid loadings is studied on the propagation of Lamb waves. The effect of the characteristic length is also studied on the phase velocity of Lamb waves in the plate for various modes in the presence of liquid loadings.
Źródło:: Journal of Theoretical and Applied Mechanics; 2015, 53, 4; 925-934
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Eigenvalue approach to nanobeam in modified couple stress thermoelastic with three-phase-lag model induced by ramp type heating
Autorzy:: Kumar, R.
Devi, S.
Powiązania:: https://bibliotekanauki.pl/articles/279203.pdf
Data publikacji:: 2017
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: modified couple stress thermoelastic
eigenvalue approach
nanobeam
Opis:: This article deals with the study of a thermoelastic nanobeam in a modified couple stress theory subjected to ramp-type heating. The mathematical model is prepared for the nanobeam in thermoelastic three-phase-lag. The Laplace transform and the eigenvalue approach are used to find the displacement component, lateral deflection, temperature change and axial stress of the thermoelastic beam. The general algorithm of the inverse Laplace transform is developed to compute results numerically. The comparison of three-phase-lag, dual-phaselag and GN-III (1993) models are represented, and their illustration is depicted graphically. This study finds the applications in engineering, medical science, sensors, etc.
Źródło:: Journal of Theoretical and Applied Mechanics; 2017, 55, 3; 1067-1079
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Modified model for shear stress distribution using TRI-1 lunar soil simulant
Autorzy:: Jayalekshmi, S.
Gireesh Kumar, P.
Powiązania:: https://bibliotekanauki.pl/articles/949124.pdf
Data publikacji:: 2018
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: TRI-1
lunar soil simulant
modified model
shear stress distribution
Opis:: In the present study, research is carried out on deriving modified analytical equations for finding shear stress distribution and known as Modified Shear Stress models (SSM) beneath plain wheels (small and large) on TRI-1 lunar soil simulant. In all four models, the Reece model, Bekker model, Wong-Reece model and Iagnemma model, normal stress and shear stress are determined, and the shear stress determination is based on the Janosi and Hanamoto (1961) model. There exists ample scope for modifying this model. A modified model for shear stress distribution is developed and the same is discussed in this paper.
Źródło:: Journal of Theoretical and Applied Mechanics; 2018, 56, 1; 137-146
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Analytical study of stress distribution models for estimation of stresses beneath plain rigid wheels and a vertical force on TRI-1 lunar soil simulant
Autorzy:: Kumar, Pala Gireesh
Jayalekshmi, S.
Powiązania:: https://bibliotekanauki.pl/articles/949136.pdf
Data publikacji:: 2019
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: TRI-1 lunar soil simulant
stress distributions
entry and exit angels
vertical force
DNSR and DSSR
Opis:: In this paper, three stress distribution models are considered, namely: Reece from 1965, Bekker from 1969, Wong-Reece from 1967. Two types of wheels are considered for the preset study, i.e., a small wheel with diameter of 160 mm and width 32 mm, whereas for a large wheel with diameter of 210 mm and width of 50 mm. TRI-1 or Tiruchirappalli soil simulant is considered for the interaction studies, which is an anorthosite based lunar soil simulant. The normal stress, shear stress and vertical forces are determined when the wheel starts moving on TRI-1 soil simulant. Entry and exit angles are also calculated for all models to estimate vertical forces. The maximum normal stress found for the small wheel was 32.121 kN/m2 (Wong-Reece model). In the case of the large wheel, the maximum normal stress was found to be 39.016 kN/m2 (Reece model). Vertical forces are found from the obtained normal stresses and shear stresses, and are presented graphically. The dimensionless stress ratio of both the wheels for the considered models, i.e., DNSR and DSSR, is also found.
Źródło:: Journal of Theoretical and Applied Mechanics; 2019, 57, 3; 791-802
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Linear stability analysis for ferromagnetic fluids in the presence of magnetic field, compressibility, internal heat source and rotation through a porous medium
Autorzy:: Kumar, K.
Singh, V.
Sharma, S.
Powiązania:: https://bibliotekanauki.pl/articles/279562.pdf
Data publikacji:: 2015
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: ferrofluids
rotation
magnetic field
porous medium
heat source
compressibility
Opis:: The effects of magnetic field and heat source strength on thermal convection of a compressible rotating ferromagnetic fluid through a porous medium are investigated theoretically using linear stability theory. A normal mode analysis method is employed to find solutions for the fluid layer confined between parallel planes with free boundaries. The cases of stationary and oscillatory instabilities are discussed. For the stationary state, compressibility, medium porosity and temperature gradient due to heat source have destabilizing effects, whereas rotation and ratio of magnetic permeability delay the onset of convection. The magnetic field and medium permeability have both stabilizing and destabilizing effects under certain conditions. The variations in the stationary critical thermal Rayleigh number and neutral instability curves in (Ra1, x)-plane for various values of physical parameters are shown graphically to depict the stability characteristics. The sufficient conditions for the non-existence of overstability are obtained and the principle of exchange of stabilities holds true in the absence of magnetic field and rotation under certain conditions.
Źródło:: Journal of Theoretical and Applied Mechanics; 2015, 53, 4; 1067-1081
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Design and development of 3-stage determination of damage location using Mamdani-Adaptive Genetic-Sugeno model
Autorzy:: Sahu, S.
Kumar, P. B.
Parhi, D. R.
Powiązania:: https://bibliotekanauki.pl/articles/281979.pdf
Data publikacji:: 2017
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: damage
Mamdani FIS
Sugeno FIS
Adaptive Genetic Algorithm
vibration
natural frequencies
Opis:: Damage detection in structural elements like beams is one of important research areas for health monitoring. Initiation of a fault in the form of a crack or any damage puts a limitation on the service life of a structural member. So, in this paper, a method is proposed which uses the advantages of soft computing techniques like Fuzzy Inference Systems (Mamdani and Sugeno) and Adaptive Genetic Algorithm for three stage refinement of the data base generated using dynamic responses from a cracked fixed-free aluminum alloy beam element. For the crack element reference, a finite element model of a single transverse crack has been considered. The proposed method describes both Mamdani and Sugeno Fuzzy Inference Systems for training of damage parameters. In the Adaptive Genetic Algorithm, a statistics based method has been incorporated to limit the randomness of the search process. Finally, the results from the Mamdani-Adaptive Genetic-Sugeno model (MAS) are validated with the results from the experimental analysis.
Źródło:: Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1325-1339
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Intelligent hybrid fuzzy logic system for damage detection of beam-like structural elements
Autorzy:: Sahu, S.
Kumar, P. B.
Parhi, D. R.
Powiązania:: https://bibliotekanauki.pl/articles/281457.pdf
Data publikacji:: 2017
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: fuzzy logic
differential evolution algorithm
crack
natural frequency
Opis:: Fuzzy logic has been used in different research fields for more than three decades. It has become a robust method to solve complex and intricate problems which are otherwise difficult to solve by traditional methods. But it still requires some human experience and knowledge. In the present study, an attempt is made to design a hybrid optimization technique for automatic formation of the fuzzy knowledge based rules using an evolutionary algorithm. This hybridization technique has been applied in the field of damage detection and location of cracks in cracked structural elements. In this paper, a robust fault diagnostic tool based on a differential evolution algorithm and fuzzy logic has been proposed. Theoretical and Finite Element analyzes are done to model the crack and to find the effect of the presence of cracks on changes of vibrational characteristic (natural frequencies) of a fixed-fixed beam. The inputs to DEA-FL system are the first three relative natural frequencies, and the outputs from the system are the relative crack depth and relative crack location. For the validation of the results obtained from the proposed method and to check the robustness of the controller, experimental analysis is performed. To find average error rates, the bootstrap method has been adopted.
Źródło:: Journal of Theoretical and Applied Mechanics; 2017, 55, 2; 509-521
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Thermal modelling, simulation and experimental validation of heat accumulation in a framed glass cabin
Autorzy:: Bera, T. K.
Dixit, S.
Bhattacharya, A.
Kumar, D.
Samantaray, A. K.
Powiązania:: https://bibliotekanauki.pl/articles/280907.pdf
Data publikacji:: 2017
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: car cabin
experimental thermal analysis
bond graph modelling
double layer glass window
Opis:: The present work concerns prediction of the amount of heat accumulation within the interior of a framed glass cabin and proposes some remedial measures to reduce temperature in the cabin. Various configurations such as double layer glass box filled with static air, static argon gas and flowing argon gas within the space between the two glass-layers are considered to conduct the experiments. Multi-physics bond graph models for these configurations are developed considering thermo-fluidic aspects. The experimental results are compared with the simulations using bond graph models. Though, direct application to a vehicle is not made, without loss of generality, the modelling and experimental procedure can be extended to analyze the heat accumulation inside a vehicle cabin when the vehicle is parked under direct sunlight.
Źródło:: Journal of Theoretical and Applied Mechanics; 2017, 55, 3; 911-922
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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