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1

The Evaluation Effect of Copper Fibre Diameter on Enhancing Compressive Strength of Pure Gypsum

Shubber Arshad Nadhom, Abbas Firas Saeed, Al-Taweel Hayder Mohammed, Ibrahim Sinan Khaleel, Al-Balhawi Ali, Al-Badran Yasir M., Dheyab Layth Sahib, Al-Ridha Ahmed S. D.

Journal of Ecological Engineering

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2023

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Vol. 24, nr 11

148--154

EN

The sustainability and impact of copper fibres on pure gypsum is the primary purpose of this study to investigate a combination of two kinds of copper fibres obtained from environmental waste (damaged electrical wires). The copper fibres are dividings into a fixed length of 10 mm, but with two different diameters: the first is 0.83 mm and the second is 0.63 mm, where the ratio of width to height (L/D) is 12 and 15.9, respectively, with a volume ratio Vf = 0.4%, the ratios 0.5 and 0.6 represent the water to gypsum ratio (W/G ) individually. Each W/G ratio has two types of mixtures which organize according to diameter. The first considers a reference mixture without copper fibres (CF), and the other is a copper fibres mixture. This work found that the compressive strength increased from adding the copper fibres to a mixture of pure gypsum. Furthermore, this increase is apparent in pure gypsum compressive strength when raising the aspect ratio because of reducing the copper fibres’ diameters. In another way, increasing ratio of W/G in the case of existing copper fibres or none may reduce a compressive strength of mixtures. Therefore, when the ratio of W/G drops, the significance of copper fibres may become more apparent.

2

Effect of aspect ratio of enclosure on free convection from horizontal cylinders in Bingham plastic fluids

Baranwal Ashok Kumar, Gupta Anoop Kumar, Tiwari Anurag Kumar, Melnik Roderick

Chemical and Process Engineering

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2022

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Vol. 43, nr 2

271--277

EN

Heat transfer in steady free convection from differentially heated cylinders enclosed in a rectangular duct filled with Bingham plastic fluids has been solved numerically for the ranges of the dimensionless groups as, Rayleigh number, 102 Ra 106; Prandtl number, 10 Pr 100 and, Bingham number, 0 Bn 50 for aspect ratios AR = 05, 0.6, 0.7, 0.8, 0.9 and 2. The streamlines, isotherm contours, yield surfaces, local and average Nusselt numbers were analysed and discussed. It is found that as the aspect ratio of the enclosure increases from 0.5 to 0.9, the average Nusselt number on the surface of the hot cylinder increases as a larger amount of fluid takes part in convection. Moreover, at sufficiently large Bingham numbers, yield stress forces dominate over buoyancy causing the flow to cease and thus the Nusselt number approaches its conduction limit. Finally, the Nusselt number approaches its conduction limit once the maximum Bingham number is reached.

3

Studies on the behaviour of steel fibre-reinforced concrete under monotonic and repeated cyclic stress in compression

Jayanth K., Shesha Prakash M. N., Suresh G. S., Naveen B. O.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e50, 2022

EN

Steel fibre-reinforced concrete (SFRC) has shown better performance behaviour with respect to the post-crack strength and in restricting the crack width and its propagation. Studies on behaviour of SFRC under repeated loading are a significant work. Behaviour of reinforced concrete structures during ground excitations in the form of earthquake forces could be significantly improved by addition of steel fibres in suitable dosage. Fibre type, aspect ratio, and dosage of fibres significantly influence the behaviour of steel fibre-reinforced concrete. Here, the work carried by various researchers with respect to the studies on the behaviour of SFRC under monotonic and cyclic stress in compression is presented. An experimental investigation on stress–strain characteristics of SFRC under monotonic loading in compression was carried, comprising M20 grade concrete, hooked-end steel fibres (l = 50 mm, diameter = 1 mm), and varying fibre dosages of 1.0, 1.25, 1.5, and 1.75% by volume of concrete. The stress–strain characteristics arrived based on the above experimental studies were compared with theoretical stress–strain characteristics, based on the equations proposed in literature. This served in understanding the behaviour of SFRC with respect to their stress–strain characteristics using experimental studies and by theoretical models, and analyse the extent of agreement and acceptance.

4

First ply failure analysis of laminated composite beam for different boundary conditions under thermo mechanical loading

Choudhury Arnab, Mondal Samar Chandra, Sarkar Susenjit

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 1

12--26

EN

Failure analysis of a laminated composite beam subjected to uniformly distributed load and thermal load is studied for different boundary conditions and fiber orientation angles, based on first ply failure load. Three different boundary conditions are studied: simply supported, fixed-fixed and fixed-free. The strength ratio is computed and compared for different failure theories. The effect of fiber orientation angle and aspect ratio on the strength ratio based on first ply failure load is presented in the paper. The strength ratio and transverse deflection are determined for Graphite/Epoxy and Glass/Epoxy composite and their hybrid combinations to find out the optimum hybrid composite beam with minimum weight, deflection and cost. The problem is solved in MATLAB platform. The mode of failure of the composite beam is determined by using maximum stress theory.

5

Investigation of thermal conductivity property of plasmonic nanofluids based on gold nanorods prepared by seed-mediated growth method

Mohammadzadeh Mahsa, Ashjari Mohsen, Zare Davoud

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2019

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nr 22(2)

119--133

EN

In this paper, nanofluids were prepared based on gold nanorods in basic fluid, water, by single-stage chemical reduction and in different volume fractions and the used gold nanorods were synthesized by seed-mediated growth method in different dimensional ratios. The properties of the prepared nanoparticles, including crystalline size, aspect ratio, surface properties, nanoparticle purity, shape and morphology of nanostructures were investigated using x-ray diffraction, UV-vis spectroscopy, FT-IR, and transmitted electron microscopy. The effect of changing parameters of Nano rod dimensions, changes in Nano rod volume fraction in water and also the effect of temperature on the nanofluid thermal conductivity coefficient were investigated using transient hot wire method. The results showed that reducing the aspect ratio, increasing the volume fraction and increasing the temperature increase the thermal conductivity. In fact, results show that an increase in the nanorods aspect ratio with a constant volume fraction of 1:50 of gold in water nanorod and at room temperature leads to a decrease in the thermal conductivity of the nanofluid. Also, increasing the two parameters of volume fraction and temperature significantly increases the thermal conductivity coefficient.

6

Analytical dynamic model of coefficient of friction of air pipeline under pressure

Dmytriv Vasyl, Dmytriv Ihor, Horodetskyy Ivan, Dmytriv Taras

Diagnostyka

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2019

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Vol. 20, No. 4

89--94

EN

To transport of the air in the pipeline, an analytical model is developed that takes into account the gas velocity, its kinematic and dynamic characteristics - density, viscosity depending on the pressure in a given space of the pipeline. The analytical model makes it possible to calculate the coefficient of friction of gas transportation in the pipeline at intervals of the absolute pressure from 220 to 2 kPa and M < 1 Mach numbers, depending on the diameter and length of the pipeline and physical and technological characteristics of the gas. The K1* aspect ratio is proposed, which characterizes in time the ratio of the dynamic force of movement of gas to the static pressure related to the diameter of the pipeline. The coefficient of air friction was modeled according to the vacuum pressure as a parameter of density and air flow. Air flow was taken from 1.917·10-3 m 3/s to 44.5·10-3 m 3/s respectively, diameters from 0.030 to 0.070 m and Mach number was M = 0.005-0.13. At the vacuum and excess pressures with increasing of Reynolds number and decreasing of Mach number the gas friction coefficient increased linearly. According to the simulation results as the pressure loss and the diameter of the pipeline are increased the friction coefficient increased as well. Analogically, at the vacuum metric pressure when the pressure loss and the diameter of the pipeline are increased the friction coefficient increased. At the pipeline internal diameters of 22, 30, 36 mm accordingly for pressure losses from 2 to 14 kPa the coefficient of air friction varies from 0.006 to 54.527 respectively.

7

Analysis of variations in and correlations between selected physical parameters of common beech (Fagus silvatica L.) nuts

Kaliniewicz Z., Markowski P., Anders A., Tylek P., Krzysiak Z., Wasielewski W.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2018

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nr 21(1)

49--63

EN

The basic dimensions and the mass of common beech nuts and seeds from five nut batches, harvested from tree stands in northern Poland, were determined. Environmental conditions had a greater influence on seed plumpness than the age of tree stands. The results of measurements were analyzed statistically by analysis of variance, correlation analysis and linear regression analysis. Despite differences in their plumpness, nuts were characterized by nearly identical cross-sections which resembled an equilateral triangle. The thickness of nuts and seeds was highly correlated with their mass, and this information can facilitate seed husking and separation into mass categories. Before and after husking, seeds should be separated with the use of a mesh screen with longitudinal openings. Medium-sized (most numerous) seeds were separated into the following plumpness categories using a screen separator with ≠6 mm and ≠7 mm openings: 84% of moderately plump seeds, 3% of seeds with reduced plumpness, and 13% of plump seeds.

8

Performance of hydrodynamic journal bearing operating under transient wear

Sharma S., Kumar Awasthi R.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 1

153--170

EN

The paper deals with a theoretical study concerning the effect of transient wear on the performance of hydrodynamic journal bearing . The eccentricity ratios are considered 0.3, 0.6 and for varying wear depth from 0.1 to 0.5 for the analysis of purpose. The Reynolds equations governing the flow of lubricant in the clearance space of a hydrodynamic journal bearing system with varying wear depth has been numerically solved using Galerkin’s FEM. The regime is assumed to be isothermal. The positive pressure zone is established using Reynolds boundary condition through iteratively. The various performance parameters which include static, dynamic and stability terms of worn journal bearing are presented with respect to relative wear depth. The journal centre motion trajectories are also obtained by numerically integrated linear and non-linear equation of motion using fourth order Runga-Kutta method. For this a computer program in Matlab was developed based on analysis to draw the linear and non linear motion trajectories and in order to validate the developed program, the numerically simulated results computed from the present study are compared with the already published results in literature. For analysis purpose the initial values of velocities and displacement are taken as ¯˙X = ¯˙Z = 0:0 and ¯x and ¯z = 0:005. The results help in predicting bearing life for smooth operation.

9

Mechanical nature of a single walled carbon nanotube using Legendre’s polynomials

Tiwari P., Nagar P.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 4

1153--1162

EN

This paper is concerned with the mechanical response of a single-walled carbon nanotube. Euler-Bernoulli’s beam theory and Hamilton’s principle are employed to derive the set of governing differential equations. An efficient variational method is used to determine the solution of the problem and Legendre’s polynomials are used to define basis functions. Significance of using these polynomials is their orthonormal property as these shape functions convert mass and stiffness matrices either to zero or one. The impact of various parameters such as length, temperature and elastic medium on the buckling load is observed and the results are furnished in a uniform manner. The degree of accuracy of the obtained results is verified with the available literature, hence illustrates the validity of the applied method. Current findings show the usage of nanostructures in vast range of engineering applications. It is worth mentioning that completely new results are obtained that are in validation with the existing results reported in literature.

10

A study on vibration of tapered non-homogeneous rectangular plate with structural parameters

Kaur N., Singhal A., Khanna A.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 4

873--884

EN

Effects of structural parameters on the vibration of a tapered non-homogeneous rectangular plate with different combinations of boundary conditions are discussed. Tapering in the plate is assumed to be sinusoidal in the x-direction. Here, temperature variation and non-homogeneity in the plate material are also considered sinusoidal in the x-direction. The Rayleigh-Ritz method is used to calculate the frequency parameter for the first two modes of vibration for different values of the structural parameters, i.e. the taper parameter, thermal gradient, aspect ratio and non-homogeneity constant. Results are obtained for three boundary conditions, i.e. clamped boundary (C-C-C-C), simply supported boundary (SS-SS-SS-SS) and clamped-simply supported boundary (CSS-C-SS). Numerical values of the frequency parameter are given in a compact tabular form.

11

Densification behaviour of carob powder

Akangbe O. L., Adamovský R., Blahovec J., Rutkowski K.

Infrastruktura i Ekologia Terenów Wiejskich

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2018

|

nr IV/1

1099--1100

EN

The behaviour of carob (Ceratonia siliqua L.) powder relevant to its densification at low pressure was determined given different equipment aspect ratios (0.5, 1.0 and 1.5) and varying rates of deformation (5.5, 10 and 14.5 mm min-1). The effects of both parameters were examined through the analysis of variance and trends were fitted to observed mechanical responses using standard regression technique. Both aspect ratio and the time rate of deformation had highly significant effects on the material’s response to load. Strain rate and specific power requirement were power functions of the equipment’s aspect ratio, at all rates of deformation. These findings furnish insights on mechanical response in compressed food powders which are applicable in modelling related food handling and processing systems.

12

Cyclic testing of steel frames infilled with concrete sandwich panels

Hashemi S. J., Razzaghi J., Moghadam A. S., Lourenço P. B.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 2

557--572

EN

In-plane seismic behaviour of concrete sandwich panel-infilled steel frame (CSP-ISF) was experimentally and numerically investigated. Four large-scale, single bay and single story steel frame specimens were tested under reversed cyclic lateral loading. Three infilled frames with different aspect ratios along with one bare frame were considered. It was found that addition of sandwich panels leads to considerable increase in the lateral stiffness and strength, ductility, energy dissipation capacity as well as equivalent viscous damping ratio of the steel frames. Furthermore, the maximum shear capacity of CSP-ISF specimens was validated by analytical approaches which showed good agreement with experimental results. Based on the present experiments, structural performance levels required for Performance-based Analysis are also proposed for concrete sandwich panel used as infill walls. Finally, a numerical model is presented to analyze the nonlinear behaviour of CSP-ISFs.

13

Buckling stability assessment of plates under uniaxial compression

Riahi Farhad, Zirakian Tadeh, Ghaderi Vahed Mam, Arya Souran

Advances in Science and Technology. Research Journal

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2018

|

Vol. 12, no 2

97--105

EN

Buckling of thin-walled and load-bearing elements of a structure can have devastating consequences. Hence, buckling checks are an integral part of strength analysis of structures. The buckling problem of thin rectangular plates subjected to in-plane compressive and/or shear loading is of great importance in building, bridge, aerospace, marine, and shipbuilding industries. When buckling occurs, thin plates undergo large out-of-plane deflections, which in turn results in the development of large bending stresses and eventually complete failure of the structure. This paper deals with the buckling stability assessment of uniaxially-compressed plates with different support conditions within the framework of classical plate theory. The main objective of this research is to explore some uncovered aspects of buckling stability of plates by considering the effects of support conditions, aspect ratio, and slenderness ratio, which will consequently result in efficient design of such thin-walled structures. To this end, in addition to validation of the numerical simulation, some case studies have been performed in order to gain a better understanding of different aspects of buckling stability of such thin-walled structures.

14

Three-port beam splitter based on a sandwiched grating with an improved aspect ratio

Shu W, Wang B, Li H, Li W, Chen L., Lei L., Zhou J.

Optica Applicata

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2015

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Vol. 45, nr 3

279--284

EN

In this paper, a fused-silica transmission grating used as a three-port beam splitter is designed by using the rigorous coupled-wave analysis, which is based on the sandwiched grating structure at the wavelength of 800 nm under normal incidence. Firstly, it is feasible to realize such a grating with the prescribed grating duty cycle and grating period. Next, high efficiency can be also achieved for both TE and TM polarizations. Moreover, the aspect ratio of the grating depth to the ridge width can be improved, which is significant for practical applications. At last, the three-port beam splitter is designed with a covering layer on the surface, which can extend its life service.

15

Thermal effect on damaged stay-cables

Wang L., Wu Y., Wang D.

Journal of Theoretical and Applied Mechanics

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2014

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Vol. 52 nr 4

1071--1082

EN

Cables may suffer severe damage in cable-stayed bridges, leading to cable relaxation and tension loss. Such a damage effect merges in the sag augmentation or tension tightened by the thermal effect. This paper is intended to investigate the static response of damaged cables coupled with the thermal effect. With the introduction of three damage parameters such as damage position, damage degree and damage range as well as temperature parameter, the dimensionless governing equations for cables are derived and the numerical method is employed to solve the nonlinear equations. The static behavior of damaged cables due to the thermal coupling effect is analyzed, and the way to remove the thermal effect is given. It shows that the aspect ratio is the major factor is the deflection of the mid-span and horizontal force in the cable, whereas the angle inclination is the next important parameter. Cables with the natural length close to the chord distance reveal the highest sensitivity to temperature, whereas pre-tensioned and non-pre-tensioned cables are less sensitive to the thermal effect. It further demonstrates that with more damage included, the sensitive scope of the variation coefficient of the axial force with aspect ratio and temperature changes dramatically.

16

Influence of wind structure and aspect ratio of circular cylinders on mean wind pressure coefficient

Lipecki T, Jamińska P.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2012

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Vol. 16, No 3-4

203--218

EN

The paper presents analyses of the mean wind pressure coefficient distribution on the surfaces of circular cylinders. The experiment was performed in a boundary layer wind tunnel in the Wind Engineering Laboratory in Cracow, Poland. Three models were examined in the wind tunnel. The influence of the aspect ratio and wind parameters (mean wind speed profile, turbulence intensity profile, power spectral density functions) on the mean wind pressure coefficient distribution and its standard deviation was considered during the tests.

17

Zastosowanie skanera 3D do monitorowania kształtu produktów spożywczych na przykładzie pieczywa

Anders A., Kaliniewicz Z., Markowski P.

Inżynieria Rolnicza

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2012

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R. 16, nr 3

7-14

PL

Zastosowanie laserowego skanera 3D pozwala na bezdotykowy pomiar i odwzorowanie powierzchni a następnie obliczenie współczynników charakteryzujących właściwości geometryczne. Dodatkową korzyścią z zastosowania bezdotykowego pomiaru geometrii za pomocą skanera 3D jest możliwość pomiaru produktów o delikatnej strukturze zewnętrznej i wrażliwych na uszkodzenia mechaniczne. Celem pracy było określenie podstawowych cech geometrycznych pieczywa typu "bułka ziarnista", wykonanie pomiarów pola powierzchni, objętości oraz określenie podstawowych jego właściwości fizycznych - masy i gęstości. Średnie pole powierzchni obliczone na podstawie modelu cyfrowego w przypadku gdy skanowany model bułki posiadał na swojej powierzchni otwory oraz gdy otwory w modelu zostały wypełnione nie różniły się istotnie. Istotne różnice wystąpiły gdy pole powierzchni i objętość bułek była obliczana ze wzorów. Obliczono również współczynniki kształtu dla badanej serii bułek.

EN

3D laser scanner application allows non-contact measurement and mapping of surfaces and calculation of the factors characterizing geometric features. An additional benefit of using noncontact measurement of geometry using the 3D scanner is the ability to measure the products of fine texture and sensitive to external mechanical damage. The aim of this paper was to determine the basic geometric features of grain bread rolls, the measurements of surface area and volume and determine its basic physical properties - mass and density. The average surface area calculated on the basis of a digital model in case when the scanned model of a bread roll had holes in its surface, and in case when the holes were filled in the model, did not differ significantly. Significant differences occurred when the surface area and volume of bread rolls was calculated from the formulas. The aspect ratios for the series of bread rolls were estimated.

18

Three-dimensional laminar dispersion of a solute in a couple-stress fluid flow through a rectangular channel

Manjunath S., Siddheshwar P. G.

International Journal of Applied Mechanics and Engineering

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2011

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Vol. 16, no 3

775-789

EN

Three-dimensional dispersion of a passive solute in a couple stress fluid through a channel of rectangular cross section is studied using the generalized miscible dispersion theory of Gill and Sankarasubramanian (1970) and Doshi et al. (1978). The effects of couple stress on the velocity and thereby the convective and dispersion coefficients are discussed. The time-dependent dispersion coefficient and mean concentration distribution are computed and the results are represented graphically for various values of the aspect ratio and couple-stress.

19

Informacyjny opis wpływu wirującego pola magnetycznego na układ dyspersyjny

Rakoczy R.

Inżynieria i Aparatura Chemiczna

|

2009

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Nr 6

158-159

PL

W pracy przedstawiono wyniki badań wpływu wirującego pola magnetycznego na kształt pęcherzy wznoszących się w różnego typu płynach. Zaprezentowano nowe podejście do opisu zmian kształtu pęcherzy, sformułowane na podstawie entropii informacji.

EN

A deformation of air bubbles rising in liquids under he action of rotating magnetic field was studied. A new approach in description of bubbles aspect ratio by means of differential entropy is presented.

20

Axially symmetric vibrations of finite composite poroelastic cylinders

Shah S. A., Tajuddin M.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 3

865-877

EN

Axially symmetric vibrations of a finite composite poroelastic circular cylinder are investigated employing Biot's theory of wave propagation in poroelastic media. The composite poroelastic cylinder consists of two poroelastic cylinders of different materials bonded at the plane ends. Frequency equations for such vibrations are derived both for pervious and impervious surfaces. Let the finite composite poroelastic cylinder be homogeneous and isotropic and the boundaries free from stress. Non-dimensional phase velocity for propagating modes is computed as a function of ratio of length of cylinders in the absence of dissipation. The results are presented graphically for two types of composite poroelastic cylinders and then discussed. In general, the phase velocity of composite cylinder-I is higher than that of composite cylinder-II both for a pervious and an impervious surface.