• Structural Engineering and Mechanics
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• v.64 no.5
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• pp.591-610
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• 2017

This paper is concerned with the static analysis of variable thickness of two directional functionally graded porous materials (FGPM) circular plate resting on a gradient hybrid foundation (Horvath-Colasanti type) with friction force and subjected to compound mechanical loads (e.g., transverse, in-plane shear traction and concentrated force at the center of the plate).The governing state equations are derived in terms of displacements based on the 3D theory of elasticity, assuming the elastic coefficients of the plate material except the Poisson's ratio varying continuously throughout the thickness and radial directions according to an exponential function. These equations are solved semi-analytically by employing the state space method (SSM) and one-dimensional differential quadrature (DQ) rule to obtain the displacements and stress components of the FGPM plate. The effect of concentrated force at the center of the plate is approximated with the shear force, uniformly distributed over the inner boundary of a FGPM annular plate. In addition to verification study and convergence analysis, numerical results are displayed to show the effect of material heterogeneity indices, foundation stiffness coefficients, foundation gradient indices, loads ratio, thickness to radius ratio, compressibility, porosity and friction coefficient of the foundation on the static behavior of the plate. Finally, the responses of FG and FG porous material circular plates to compound mechanical loads are compared.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.49-60
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• 1996

An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) withdifferent leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison test. Pressure drops of MLPVS are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of the polymer valve, the larger are the corresponding pressure drop. The velocity profiles for MLPs reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVS at a flow rate of $30{\ell}$/min are in the range 50-130 dyn/$cm^2$, and the corresponding maximum Reynolds shear stresses are in the range of 100-500 dyn/$cm^2$, respectively, which are beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it may be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the Important parameters.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.241-246
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• 1995

An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) with different leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison tests. Pressure drops of MLPVs are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of a polymer valve, the larger arc the corresponding press drop. The velocity profiles for MLPV reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVs at a flow rate of 30 l/min are in the range $54-130\;dyn/cm^2$, and the corresponding maximum. Reynolds shear stresses are in the range of $100-500\;dyn/cm^2$, respectively. Both arc beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it can be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the important parameters.

• Fashion & Textile Research Journal
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• v.22 no.4
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• pp.515-522
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• 2020

This study examined the effect of the blend ratio of wool and polyester fibers, yarn and fabric structural parameters to the appearance property and the formability of worsted fabrics. The mechanical properties of twenty types of manufactured worsted and PET/wool blend fabrics were measured using KES-FB and FAST systems. Garment formability increases with the thickness and cover factor as well as increases with wool content. The correlation between KES-FB and FAST system showed a relatively high correlation with an extensibility of 0.98, bending and shear rigidity 0.71; both were higher than polyester synthetic fiber. The correlation coefficient of garment formability between KES-FB and FAST systems was 0.93 and the correlation coefficient between formability and fabric extensibility was 0.8. These results were higher than those of bending and shear rigidity. This revealed that garment formability was influenced by wool content, cover factor and fabric thickness; however, wool content and fabric thickness were the most important factors for the seam pucker. The garment formability of the worsted fabrics can be predicted by fabric mechanical properties measured from KES-FB and FAST systems.

• Structural Engineering and Mechanics
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• v.63 no.5
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• pp.585-595
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• 2017

This study aimed to presents a simple analytical approach to investigate the thermal buckling behavior of thick functionally graded sandwich by employing both the sinusoidal shear deformation theory and stress function. The material properties of the sandwich plate faces are continuously varied within the plate thickness according to a simple power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. The thermal loads are considered as uniform, linear and non-linear temperature rises across the thickness direction. Numerical examples are presented to prove the effect of power law index, loading type and functionally graded layers thickness on the thermal buckling response of thick functionally graded sandwich.

• Steel and Composite Structures
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• v.33 no.5
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• pp.629-640
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• 2019

This paper presents a theoretical and finite element (FE) study on the stress intensity factors of double-edged cracked steel beams strengthened with carbon fiber reinforced polymer (CFRP) plates. By simplifying the tension flange of the steel beam using a steel plate in tension, the solutions obtained for the stress intensity factors of the double-edged cracked steel plate strengthened with CFRP plates were used to evaluate those of the steel beam specimens. The correction factor α₁ was modified based on the transformed section method, and an additional correction factor φ was introduced into the expressions. Three-dimensional FE modeling was conducted to calculate the stress intensity factors. Numerous combinations of the specimen geometry, crack length, CFRP thickness and Young's modulus, adhesive thickness and shear modulus were analyzed. The numerical results were used to investigate the variations in the stress intensity factor and the additional correction factor φ. The proposed expressions are a function of applied stress, crack length, the ratio between the crack length and half the width of the tension flange, the stiffness ratio between the CFRP plate and tension flange, adhesive shear modulus and thickness. Finally, the proposed expressions were verified by comparing the theoretical and numerical results.

• Steel and Composite Structures
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• v.39 no.3
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• pp.275-290
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• 2021

The main purpose of this research work is to investigate the critical buckling load of functionally graded (FG) porous plates with graphene platelets (GPLs) reinforcement using generalized differential quadrature (GDQ) method at thermal condition. It is supposed that the GPL nanofillers and the porosity coefficient vary continuously along the plate thickness direction. Generally, the thermal distribution is considered to be nonlinear and the temperature changing continuously through the thickness of the nanocomposite plates according to the power-law distribution. To model closed cell FG porous material reinforced with GPLs, Halpin-Tsai micromechanical modeling in conjunction with Gaussian-Random field scheme are used, through which mechanical properties of the structures can be extracted. Based on the third order shear deformation theory (TSDT) and the Hamilton's principle, the equations of motion are established and solved for various boundary conditions (B.Cs). The fast rate of convergence and accuracy of the method are investigated through the different solved examples and validity of the present study is evaluated by comparing its numerical results with those available in the literature. A special attention is drawn to the role of GPLs weight fraction, GPLs patterns through the thickness, porosity coefficient and distribution of porosity on critical buckling load. Results reveal that the importance of thermal condition on of the critical load of FGP-GPL reinforced nanocomposite plates.

• Advances in nano research
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• v.11 no.6
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• pp.621-640
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• 2021

Effect of thickness stretching on mechanical behavior of functionally graded (FG) carbon nanotubes reinforced composite (CNTRC) laminated nanoplates resting on elastic foundation is analyzed in this paper using a novel quasi 3D higher-order shear deformation theory. The key feature of this theoretical formulation is that, in addition to considering the thickness stretching effect, the number of unknowns of the displacement field is reduced to four, and which is more than five in the other models. Single-walled carbon nanotubes (SWCNTs) are the reinforced elements and are distributed with four power-law functions which are, uniform distribution, V-distribution, O-distribution and X-distribution. To cover various boundary conditions, an analytical solution is developed based on Galerkin method to solve the governing equilibrium equations by considering the nonlocal strain gradient theory. A modified two-dimensional variable Winkler elastic foundation is proposed in this study for the first time. A parametric study is executed to determine the influence of the reinforcement patterns, power-law index, nonlocal parameter, length scale parameter, thickness and aspect ratios, elastic foundation, thermal environments, and various boundary conditions on stresses, displacements, buckling loads and frequencies of the CNTRC laminated nanoplate.

• Smart Structures and Systems
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• v.29 no.3
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• pp.395-420
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• 2022

A new hybrid quasi-3D and 2D high-order shear deformation theory is studied in this mathematical formulation, for an investigation of the bending, free vibrations and buckling influences on a functionally graded material plate. The theoretical formulation has been begun by a displacement field of five unknowns, governing the transverse displacement across the thickness of the plate by bending, shearing and stretching. The transverse shear deformation effect has been taken into consideration, satisfying the stress-free boundary conditions, especially on plate free surfaces as parabolic variation through its thickness. Thus, the mechanical properties of the functionally graded plate vary across the plate thickness, following three distributions forms: the power law, exponential form and the Mori-Tanaka scheme. The mechanical properties are used to develop the equations of motion, obtained from the Hamilton principle, and solved by applying the Navier-type solution for simply supported boundary conditions. The results obtained are compared with other solutions of 2D, 3D and quasi-3D plate theories have been found in the literature.

• Computers and Concrete
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• v.32 no.1
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• pp.87-97
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• 2023

The bending of a porous FG plate is discussed in this study using a novel higher quasi-3D hyperbolic shear deformation theory with four unknowns. The proposed theory takes into consideration the normal and transverse shear deformation effect and ensures the parabolic distribution of the transverse stresses through the thickness direction with zero-traction at the top and the bottom surfaces of the structure. Innovative porous functionally graded materials (FGM) have through-thickness porosity as a unique attribute that gradually varies with their qualities. An analytical solution of the static response of the perfect and imperfect FG plate was derived based on the virtual work principle and solved using Navier's procedure. The validity and the efficiency of the current model is confirmed by comparing the results with those obtained by others solutions. The comparisons showed that the present model is very efficient and simple in terms of computation time and exactness. The impact of the porosity parameter, aspect ratio, and thickness ratio on the bending of porous FG plate is shown through a discussion of several numerical results.