H. Callioglu - Academia.edu (original) (raw)

Papers by H. Callioglu

Research paper thumbnail of Comparative Analysis of Free Optical Vibration of Lamination Composite Optical Beams Using the Boubaker Polynomials Expansion Scheme and the Differential Quadrature Method

ISRN Optics, 2012

The effects of stacking sequences of composite laminated optical beams on free vibration frequenc... more The effects of stacking sequences of composite laminated optical beams on free vibration frequencies are investigated using two methods: the Boubaker Polynomials Expansion Scheme (pbes) and the Differential Quadrature Method (dqm). In the last decades, these two techniques have been separately performed for obtaining accurate numerical solutions to several initial boundary value problems (Vo et al. 2010, Li et al. 2008, Chen 2003, Hu et al. 2008, Karami et al. 2003, Malekzadeh et al. 2004, Khare et al. 2004, Della and Shu 2005, Ramtekkar et al. 2002, Adam 2003). Conjointly yielded results are compared and discussed.

Research paper thumbnail of Stress analysis of functionally graded rotating discs: analytical and numerical solutions

Acta Mechanica Sinica, 2011

ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally gra... more ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally graded materials (FGMs). Elasticity modulus and density of the discs are assumed to vary radially according to a power law function, but the material is of constant Poisson’s ratio. A gradient parameter n is chosen between 0 and 1.0. When n = 0, the disc becomes a homogeneous isotropic material. Tangential and radial stress distributions and displacements on the disc are investigated for various gradient parameters n by means of the diverse elasticity modulus and density by using analytical and numerical solutions. Finally, a homogenous tangential stress distribution and the lowest radial stresses along the radius of a rotating disc are approximately obtained for the gradient parameter n = 1.0 compared with the homogeneous, isotropic case n = 0. This means that a disc made of FGMs has the capability of higher angular rotations compared with the homogeneous isotropic disc.

Research paper thumbnail of Thermal Loads

The analytical study deals with stress analysis of functionally graded rotating annular discs sub... more The analytical study deals with stress analysis of functionally graded rotating annular discs subjected to internal pressure and various temperature distributions, such as uniform T(0) (reference temperature), linearly increasing T(b) (outer surface temperature) and decreasing T(a) (inner surface temperature) in radial direction. Infinitesimal deformation theory of elasticity and for graded parameters power law functions are used in the solution procedure. The results show that the tangential stresses increase at the inner surface and decrease at the outer surface with increasing T(0) and T(b) temperatures. If T(a) is increased, they decrease at the inner surface and rise at the outer surface. The radial stresses reduce gradually along the radial section with increasing T(0) and T(a) temperatures, whereas they rise along the radial section when T(b) is increased. The radial displacement values in the discs subjected to uniform temperature T(0) are higher compared to the discs subjec...

Research paper thumbnail of Thermal elastic-plastic stress analysis ofan aluminium composite disc under linearly decreasing thermal loading

In this study, an elastic-plastic thermal stress analysis of an orthotopic aluminium metal matrix... more In this study, an elastic-plastic thermal stress analysis of an orthotopic aluminium metal matrix composite disc with a hole has been investigated analytically for non-linear hardening material behaviour. The aluminium composite disc reinforced curvilinearly by steel fibres is produced under hydraulic press. The mechanical properties of the composite disc are obtained by tests. A computer program is developed to calculate the thermal stresses under a linearly decreasing temperature from inner surface to outer surface. Elastic, elastic-plastic and residual thermal stress distributions are obtained analytically from inner surface to outer surface and they are presented in tables and Fig.s. The elastic-plastic solution is performed for the plastic region expanding around the inner surface. The magnitude of the tangential stress component has been found out in this study to be higher than the magnitude of the radial stress component. Besides, the tangential stress component is compressi...

Research paper thumbnail of Supported Edges

In this study, free vibration behaviors of a multiliyered symmetric sandwich beam made of functio... more In this study, free vibration behaviors of a multiliyered symmetric sandwich beam made of functionally graded materials are investigated. The material properties of the functionally graded sandwich beam are assumed to vary through the thickness according to the power and exponential laws. In order to provide this, fifty layered beam is considered. Each layer is isotropic and homogeneous although the volume fractions of the constituents of the layers are different. The effect of variation of mass density is also taken into account in addition to Young's modulus by using mixture rules and laminate theory. Furthermore, natural frequencies are computed for simply-supported boundary conditions of FG sandwich beam using theoretical procedure based on Timoshenko and Euler-Bernoulli theorems. The effects of slenderness ratio and power index are also discussed. Finally, the obtained results are compared with the reported studies and ANSYS (R) and found to be consistent with each other

Research paper thumbnail of Performance of Composite Structures

The present study was designed to examine experimentally the effects of butterfly fitting clearan... more The present study was designed to examine experimentally the effects of butterfly fitting clearances and different adhesives on the load carrying abilities of the composite structures joined via a butterfly-shaped joining component and the fatigue performance of the specimens joined by the best joint style obtained. Experiment specimens and butterfly-shaped locking components were cut from a composite plate by means of water jet. Fatigue experiments were conducted at the constant load ratio and at different maximum fatigue loads. To compare the fatigue performance, the fatigue experiments of the butt joints were also carried out. According to the experiment results obtained, it was determined that fatigue strengths of adhesively-bonded butterfly joints have a longer life span than those of the bonded butt joints under the same circumstances. The present study has made it possible that with the use of butterfly joining component, the earliest damage should occur on the butterfly and ...

Research paper thumbnail of Stress analysis of functionally graded rotating discs: analytical and

SPRINGER HEIDELBERG, 2011

ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally gra... more ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally graded materials (FGMs). Elasticity modulus and density of the discs are assumed to vary radially according to a power law function, but the material is of constant Poisson’s ratio. A gradient parameter n is chosen between 0 and 1.0. When n = 0, the disc becomes a homogeneous isotropic material. Tangential and radial stress distributions and displacements on the disc are investigated for various gradient parameters n by means of the diverse elasticity modulus and density by using analytical and numerical solutions. Finally, a homogenous tangential stress distribution and the lowest radial stresses along the radius of a rotating disc are approximately obtained for the gradient parameter n = 1.0 compared with the homogeneous, isotropic case n = 0. This means that a disc made of FGMs has the capability of higher angular rotations compared with the homogeneous isotropic disc.

Research paper thumbnail of Elasto-plastic thermal stress analysis of functionally graded hyperbolic discs

Structural Engineering and Mechanics, 2017

The objective of this analytical study is to calculate the elasto-plastic stresses of Functionall... more The objective of this analytical study is to calculate the elasto-plastic stresses of Functionally Graded (FG) hyperbolic disc subjected to uniform temperature. The material properties (elastic modulus, thermal expansion coefficient and yield strength) and the geometry (thickness) of the disc are assumed to vary radially with a power law function, but Poisson's ratio does not vary. FG disc material is assumed to be non-work hardening. Radial and tangential stresses are obtained for various thickness profile, temperature and material properties. The results indicate that thickness profile and volume fractions of constituent materials play very important role on the thermal stresses of the FG hyperbolic discs. It is seen that thermal stresses in a disc with variable thickness are lower than those with constant thickness at the same temperature. As a result of this, variations in the thickness profile increase the operation temperature. Moreover, thickness variation in the discs provides a significant weight reduction. A disc with lower rigidity at the inner surface according to the outer surface should be selected to obtain almost homogenous stress distribution and to increase resistance to temperature. So, discs, which have more rigid region at the outer surface, are more useful in terms of resistance to temperature

Research paper thumbnail of Effects of cold pressing and extrusion on the microstructures and mechanical properties of SiC and B 4 C reinforced Alumix-231 alloys

Scientific Research and Essays, Mar 31, 2011

In this research, mechanical and microstructure properties of cold pressing (CP) and extrusion (E... more In this research, mechanical and microstructure properties of cold pressing (CP) and extrusion (EXTR) specimens produced via powder metallurgy were investigated and compared. For this comparison, EXTR specimens were hot extruded at 565°C with an extrusion ratio of 4:1. Likewise, CP specimens were compacted under a pressure of 600 MPa and sintered at 565°C. Then, the effects of volume fraction on SiC and B 4C particle reinforced Alumix–231 composites were investigated using optical microscopy, SEM and macro hardness testing. Compared to CP specimens, it was found that the hardness and mechanical strengths of Alumix–231 specimens without reinforcement produced using EXTR increased in the ratio of 140 and 190%, respectively. The test results showed that increase in uniformity of reinforcement dispersion and enhancement of interfacial bonding strength of the composites is the main reasons for the improvement of EXTR specimens. As a result, EXTR improves mechanical properties of the specimens by decreasing the porosity and thus increasing the density and interfacial bonding strength.

Research paper thumbnail of Vibration Analysis of Multiple Delaminated Composite Beams

Advanced Composite Materials, 2012

In this study, the effects of location, size and number of delaminations, boundary conditions, or... more In this study, the effects of location, size and number of delaminations, boundary conditions, orientation angles and stacking sequences on the natural frequency of laminated composite beams are investigated experimentally, analytically and numerically. Two-dimensional finite element models of the delaminated beams are obtained using ANSYS (Finite ElementMethod Code). The analytical method is developed using Euler–Bernoulli beam theory. Then, analytical results

Research paper thumbnail of Production of epoxy composites reinforced by different natural fibers and their mechanical properties

Composites Part B: Engineering, 2019

The aim of this research is the production of epoxy resin composites reinforced by birch, palm, a... more The aim of this research is the production of epoxy resin composites reinforced by birch, palm, and eucalyptus fibers with resin transfer molding technique and molded fiber production technique combination. The tensile stress of birch, palm, and eucalyptus reinforced epoxy composites were determined as 29.53, 42.24, and 45.28 MPa, respectively. Bending stress of birch, palm and eucalyptus reinforced epoxy composites were found as 58.83, 68.58, and 79.92 MPa, respectively. The birch epoxy composite had 0.105 J impact energy while palm and eucalyptus epoxy composites were determined as 0.130 and 0.124 J, respectively. It is clearly observed that fiber type was very effective on mechanical properties of composites. The results of studies showed that molded fiber production method had a very promising future for the development of natural fiber reinforced composites.

Research paper thumbnail of Free vibration and buckling analysis of the impacted hybrid composite beams

Structural Engineering and Mechanics, 2016

The aim of this experimental study is to investigate the free vibration and buckling behaviors of... more The aim of this experimental study is to investigate the free vibration and buckling behaviors of hybrid composite beams having different span lengths and orientation angles subjected to different impact energy levels. The impact energies are applied in range from 10 J to 30 J. Free vibration and buckling behaviors of intact and impacted hybrid composite beams are compared with each other for different span lengths, orientation angles and impact levels. In free vibration analysis, the first three modes of hybrid beams are considered and natural frequencies are normalized. It is seen that first and second modes are mostly affected with increasing impact energy level. Also, the fundamental natural frequency is mostly affected with the usage of mold that have 40 mm span length (SP40). Moreover, as the impact energy increases, the normalized critical buckling loads decrease gradually for 0 and 30 oriented hybrid beams but they fluctuate for the other beams

Research paper thumbnail of Elastic-plastic stress analysis of symmetric reinforced thermoplastic matrix laminated beams under a bending moment

Research paper thumbnail of The flexural behaviors of the impacted composite single-lap adhesive joints

Science and Engineering of Composite Materials, 2015

This experimental study deals with the flexural behaviors of composite single-lap adhesive joints... more This experimental study deals with the flexural behaviors of composite single-lap adhesive joints after impact tests. Increasing impact energies are applied at the center of the composite plates having three different overlap lengths. It is shown that the overlap lengths and impact energy levels affect considerably the impact responses of the composite single-lap joints. It is also shown that the bending stiffness of the composite increases with increasing overlap length. For this reason, after the impact tests, how these effects influence the flexural behaviors of the impacted composite lap joints was also investigated. The flexural loads of the impacted and non-impacted composite single-lap joints were determined and compared with each other. It is shown that the residual flexural loads after impact increase with increasing overlap lengths but decrease with increasing impact energy.

Research paper thumbnail of Buckling behaviors of the impacted composite plates

Science and Engineering of Composite Materials, 2014

ABSTRACT The aim of this experimental study is to investigate the buckling behaviors after impact... more ABSTRACT The aim of this experimental study is to investigate the buckling behaviors after impact of the composite plates. The increasing impact energies, which ranged from approximately 3-15 J, are performed at three different impact points of the composite plates having three different thicknesses until vicinity of the penetration threshold of specimens. After the impact tests, the effects of the different impact points, energy levels, and thickness on the buckling behaviors of the impacted specimens are investigated. Also, compared with nonimpacted specimens, the buckling loads are presented nondimensionally. As expected, the lowest critical buckling load occurs in thin plates impacted at the center point. The critical buckling loads become more stable both by increasing number of layers and in the impact points that are away from the center.

Research paper thumbnail of Elastic–plastic stress analysis of rotating functionally graded discs

Thin-Walled Structures, 2015

In this study, elastic-plastic stress analysis of Functionally Graded (FG) discs subjected to con... more In this study, elastic-plastic stress analysis of Functionally Graded (FG) discs subjected to constant angular velocity is investigated. Yielding behavior of the disc material is considered to be non-work hardening case. Elasticity modulus, density and yield strength of the disc vary radially according to a power law function. To see the distribution of the plastic region, different angular velocities are taken into consideration for such an analysis. Radial and tangential stress components are obtained for the angular velocities and gradient parameters. It is seen that the results obtained from analytical and numerical (ANSYS s) solutions are in good agreement.

Research paper thumbnail of Vibration behavior of a radially functionally graded annular disc with variable geometry

Science and Engineering of Composite Materials, 2014

In this study, the free vibration behavior of an annular disc made of functionally graded materia... more In this study, the free vibration behavior of an annular disc made of functionally graded material (FGM) with variable geometry is investigated. The elasticity modulus, density, and thickness of the disc are assumed to vary through the radial direction according to the power law so that the effects of their indexes on the natural frequency of the disc are investigated. The Poisson’s ratio is assumed as a constant. The natural frequencies of the disc are calculated for various boundary conditions by using classical plate theory, and the various types of mode shapes, which are described by the number of nodal diameters and nodal circles, are also discussed. Moreover, the effects of the ratio of the inner radius to the outer radius on the natural frequency are also considered. It is found that in order to increase the natural frequency, the elasticity modulus and thickness should be increased at the inner surface, whereas density should be increased at the outer surface. The natural fr...

Research paper thumbnail of Thermal Stress Analysis of Curvilinearly Orthotropic Rotating Discs

Journal of Thermoplastic Composite Materials, 2007

This study deals with stress analysis on orthotropic rotating annular discs subjected to various ... more This study deals with stress analysis on orthotropic rotating annular discs subjected to various temperature distributions, such as uniform, linearly increasing and decreasing with radius temperatures. Tangential and radial stresses in a rotating disc under the three different temperature profiles are plotted in figures. With the increasing temperature, the tangential stress component decreases at the inner surface whereas it increases at the outer surface, and the radial stress component reduces gradually for all the temperature distributions. The magnitude of the tangential stress component is higher than that of the radial stress component for all the discs under the lower temperatures of the temperature distributions. But, when the temperature is further increased, the tangential stress component decreases more at the inner surface. The radial displacement is also calculated analytically and has higher value at the outer surface than that of the inner surface for all the tempera...

Research paper thumbnail of Three-dimensional Buckling Analysis of Thermoplastic Composite Laminated Plates with Single Vertical or Horizontal Strip Delamination

Journal of Thermoplastic Composite Materials, 2004

... load, boundary condi-tions and symmetrical model geometry. It can be said that there will not... more ... load, boundary condi-tions and symmetrical model geometry. It can be said that there will not be important effects of the contact elements in this type of buck-ling analysis. Furthermore, this case has been also examined by ...

Research paper thumbnail of Thermal Elastic–Plastic Stress Analysis of Aluminum Metal–Matrix Composite Laminated Plates Under a Parabollically Temperature Distribution

Journal of Reinforced Plastics and Composites, 2004

In this study, a thermal elastic–plastic stress analysis is carried out on steel-fiberreinforced ... more In this study, a thermal elastic–plastic stress analysis is carried out on steel-fiberreinforced aluminum metal–matrix composite laminated plates fixed at all edges. Temperature is chosen to vary parabollically. It is zero and T0 on the middle axis and at the upper–lower surfaces, respectively. The solution is executed for symmetric cross-ply (0° /90°)2 and angle-ply (30° / -30°)2, (45° / -45°)2, (60° / -60°)2 laminated plates. The elastic–plastic solution is carried out for small plastic deformations. The Tsai–Hill Theory is used as a yield criterion. Residual stress distributions along the thickness of the plates are obtained. All the residual stress components are in static balance with respect to middle plane of the laminates since they are symmetric in opposite signs.

Research paper thumbnail of Comparative Analysis of Free Optical Vibration of Lamination Composite Optical Beams Using the Boubaker Polynomials Expansion Scheme and the Differential Quadrature Method

ISRN Optics, 2012

The effects of stacking sequences of composite laminated optical beams on free vibration frequenc... more The effects of stacking sequences of composite laminated optical beams on free vibration frequencies are investigated using two methods: the Boubaker Polynomials Expansion Scheme (pbes) and the Differential Quadrature Method (dqm). In the last decades, these two techniques have been separately performed for obtaining accurate numerical solutions to several initial boundary value problems (Vo et al. 2010, Li et al. 2008, Chen 2003, Hu et al. 2008, Karami et al. 2003, Malekzadeh et al. 2004, Khare et al. 2004, Della and Shu 2005, Ramtekkar et al. 2002, Adam 2003). Conjointly yielded results are compared and discussed.

Research paper thumbnail of Stress analysis of functionally graded rotating discs: analytical and numerical solutions

Acta Mechanica Sinica, 2011

ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally gra... more ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally graded materials (FGMs). Elasticity modulus and density of the discs are assumed to vary radially according to a power law function, but the material is of constant Poisson’s ratio. A gradient parameter n is chosen between 0 and 1.0. When n = 0, the disc becomes a homogeneous isotropic material. Tangential and radial stress distributions and displacements on the disc are investigated for various gradient parameters n by means of the diverse elasticity modulus and density by using analytical and numerical solutions. Finally, a homogenous tangential stress distribution and the lowest radial stresses along the radius of a rotating disc are approximately obtained for the gradient parameter n = 1.0 compared with the homogeneous, isotropic case n = 0. This means that a disc made of FGMs has the capability of higher angular rotations compared with the homogeneous isotropic disc.

Research paper thumbnail of Thermal Loads

The analytical study deals with stress analysis of functionally graded rotating annular discs sub... more The analytical study deals with stress analysis of functionally graded rotating annular discs subjected to internal pressure and various temperature distributions, such as uniform T(0) (reference temperature), linearly increasing T(b) (outer surface temperature) and decreasing T(a) (inner surface temperature) in radial direction. Infinitesimal deformation theory of elasticity and for graded parameters power law functions are used in the solution procedure. The results show that the tangential stresses increase at the inner surface and decrease at the outer surface with increasing T(0) and T(b) temperatures. If T(a) is increased, they decrease at the inner surface and rise at the outer surface. The radial stresses reduce gradually along the radial section with increasing T(0) and T(a) temperatures, whereas they rise along the radial section when T(b) is increased. The radial displacement values in the discs subjected to uniform temperature T(0) are higher compared to the discs subjec...

Research paper thumbnail of Thermal elastic-plastic stress analysis ofan aluminium composite disc under linearly decreasing thermal loading

In this study, an elastic-plastic thermal stress analysis of an orthotopic aluminium metal matrix... more In this study, an elastic-plastic thermal stress analysis of an orthotopic aluminium metal matrix composite disc with a hole has been investigated analytically for non-linear hardening material behaviour. The aluminium composite disc reinforced curvilinearly by steel fibres is produced under hydraulic press. The mechanical properties of the composite disc are obtained by tests. A computer program is developed to calculate the thermal stresses under a linearly decreasing temperature from inner surface to outer surface. Elastic, elastic-plastic and residual thermal stress distributions are obtained analytically from inner surface to outer surface and they are presented in tables and Fig.s. The elastic-plastic solution is performed for the plastic region expanding around the inner surface. The magnitude of the tangential stress component has been found out in this study to be higher than the magnitude of the radial stress component. Besides, the tangential stress component is compressi...

Research paper thumbnail of Supported Edges

In this study, free vibration behaviors of a multiliyered symmetric sandwich beam made of functio... more In this study, free vibration behaviors of a multiliyered symmetric sandwich beam made of functionally graded materials are investigated. The material properties of the functionally graded sandwich beam are assumed to vary through the thickness according to the power and exponential laws. In order to provide this, fifty layered beam is considered. Each layer is isotropic and homogeneous although the volume fractions of the constituents of the layers are different. The effect of variation of mass density is also taken into account in addition to Young's modulus by using mixture rules and laminate theory. Furthermore, natural frequencies are computed for simply-supported boundary conditions of FG sandwich beam using theoretical procedure based on Timoshenko and Euler-Bernoulli theorems. The effects of slenderness ratio and power index are also discussed. Finally, the obtained results are compared with the reported studies and ANSYS (R) and found to be consistent with each other

Research paper thumbnail of Performance of Composite Structures

The present study was designed to examine experimentally the effects of butterfly fitting clearan... more The present study was designed to examine experimentally the effects of butterfly fitting clearances and different adhesives on the load carrying abilities of the composite structures joined via a butterfly-shaped joining component and the fatigue performance of the specimens joined by the best joint style obtained. Experiment specimens and butterfly-shaped locking components were cut from a composite plate by means of water jet. Fatigue experiments were conducted at the constant load ratio and at different maximum fatigue loads. To compare the fatigue performance, the fatigue experiments of the butt joints were also carried out. According to the experiment results obtained, it was determined that fatigue strengths of adhesively-bonded butterfly joints have a longer life span than those of the bonded butt joints under the same circumstances. The present study has made it possible that with the use of butterfly joining component, the earliest damage should occur on the butterfly and ...

Research paper thumbnail of Stress analysis of functionally graded rotating discs: analytical and

SPRINGER HEIDELBERG, 2011

ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally gra... more ABSTRACT This study deals with stress analysis of annular rotating discs made of functionally graded materials (FGMs). Elasticity modulus and density of the discs are assumed to vary radially according to a power law function, but the material is of constant Poisson’s ratio. A gradient parameter n is chosen between 0 and 1.0. When n = 0, the disc becomes a homogeneous isotropic material. Tangential and radial stress distributions and displacements on the disc are investigated for various gradient parameters n by means of the diverse elasticity modulus and density by using analytical and numerical solutions. Finally, a homogenous tangential stress distribution and the lowest radial stresses along the radius of a rotating disc are approximately obtained for the gradient parameter n = 1.0 compared with the homogeneous, isotropic case n = 0. This means that a disc made of FGMs has the capability of higher angular rotations compared with the homogeneous isotropic disc.

Research paper thumbnail of Elasto-plastic thermal stress analysis of functionally graded hyperbolic discs

Structural Engineering and Mechanics, 2017

The objective of this analytical study is to calculate the elasto-plastic stresses of Functionall... more The objective of this analytical study is to calculate the elasto-plastic stresses of Functionally Graded (FG) hyperbolic disc subjected to uniform temperature. The material properties (elastic modulus, thermal expansion coefficient and yield strength) and the geometry (thickness) of the disc are assumed to vary radially with a power law function, but Poisson's ratio does not vary. FG disc material is assumed to be non-work hardening. Radial and tangential stresses are obtained for various thickness profile, temperature and material properties. The results indicate that thickness profile and volume fractions of constituent materials play very important role on the thermal stresses of the FG hyperbolic discs. It is seen that thermal stresses in a disc with variable thickness are lower than those with constant thickness at the same temperature. As a result of this, variations in the thickness profile increase the operation temperature. Moreover, thickness variation in the discs provides a significant weight reduction. A disc with lower rigidity at the inner surface according to the outer surface should be selected to obtain almost homogenous stress distribution and to increase resistance to temperature. So, discs, which have more rigid region at the outer surface, are more useful in terms of resistance to temperature

Research paper thumbnail of Effects of cold pressing and extrusion on the microstructures and mechanical properties of SiC and B 4 C reinforced Alumix-231 alloys

Scientific Research and Essays, Mar 31, 2011

In this research, mechanical and microstructure properties of cold pressing (CP) and extrusion (E... more In this research, mechanical and microstructure properties of cold pressing (CP) and extrusion (EXTR) specimens produced via powder metallurgy were investigated and compared. For this comparison, EXTR specimens were hot extruded at 565°C with an extrusion ratio of 4:1. Likewise, CP specimens were compacted under a pressure of 600 MPa and sintered at 565°C. Then, the effects of volume fraction on SiC and B 4C particle reinforced Alumix–231 composites were investigated using optical microscopy, SEM and macro hardness testing. Compared to CP specimens, it was found that the hardness and mechanical strengths of Alumix–231 specimens without reinforcement produced using EXTR increased in the ratio of 140 and 190%, respectively. The test results showed that increase in uniformity of reinforcement dispersion and enhancement of interfacial bonding strength of the composites is the main reasons for the improvement of EXTR specimens. As a result, EXTR improves mechanical properties of the specimens by decreasing the porosity and thus increasing the density and interfacial bonding strength.

Research paper thumbnail of Vibration Analysis of Multiple Delaminated Composite Beams

Advanced Composite Materials, 2012

In this study, the effects of location, size and number of delaminations, boundary conditions, or... more In this study, the effects of location, size and number of delaminations, boundary conditions, orientation angles and stacking sequences on the natural frequency of laminated composite beams are investigated experimentally, analytically and numerically. Two-dimensional finite element models of the delaminated beams are obtained using ANSYS (Finite ElementMethod Code). The analytical method is developed using Euler–Bernoulli beam theory. Then, analytical results

Research paper thumbnail of Production of epoxy composites reinforced by different natural fibers and their mechanical properties

Composites Part B: Engineering, 2019

The aim of this research is the production of epoxy resin composites reinforced by birch, palm, a... more The aim of this research is the production of epoxy resin composites reinforced by birch, palm, and eucalyptus fibers with resin transfer molding technique and molded fiber production technique combination. The tensile stress of birch, palm, and eucalyptus reinforced epoxy composites were determined as 29.53, 42.24, and 45.28 MPa, respectively. Bending stress of birch, palm and eucalyptus reinforced epoxy composites were found as 58.83, 68.58, and 79.92 MPa, respectively. The birch epoxy composite had 0.105 J impact energy while palm and eucalyptus epoxy composites were determined as 0.130 and 0.124 J, respectively. It is clearly observed that fiber type was very effective on mechanical properties of composites. The results of studies showed that molded fiber production method had a very promising future for the development of natural fiber reinforced composites.

Research paper thumbnail of Free vibration and buckling analysis of the impacted hybrid composite beams

Structural Engineering and Mechanics, 2016

The aim of this experimental study is to investigate the free vibration and buckling behaviors of... more The aim of this experimental study is to investigate the free vibration and buckling behaviors of hybrid composite beams having different span lengths and orientation angles subjected to different impact energy levels. The impact energies are applied in range from 10 J to 30 J. Free vibration and buckling behaviors of intact and impacted hybrid composite beams are compared with each other for different span lengths, orientation angles and impact levels. In free vibration analysis, the first three modes of hybrid beams are considered and natural frequencies are normalized. It is seen that first and second modes are mostly affected with increasing impact energy level. Also, the fundamental natural frequency is mostly affected with the usage of mold that have 40 mm span length (SP40). Moreover, as the impact energy increases, the normalized critical buckling loads decrease gradually for 0 and 30 oriented hybrid beams but they fluctuate for the other beams

Research paper thumbnail of Elastic-plastic stress analysis of symmetric reinforced thermoplastic matrix laminated beams under a bending moment

Research paper thumbnail of The flexural behaviors of the impacted composite single-lap adhesive joints

Science and Engineering of Composite Materials, 2015

This experimental study deals with the flexural behaviors of composite single-lap adhesive joints... more This experimental study deals with the flexural behaviors of composite single-lap adhesive joints after impact tests. Increasing impact energies are applied at the center of the composite plates having three different overlap lengths. It is shown that the overlap lengths and impact energy levels affect considerably the impact responses of the composite single-lap joints. It is also shown that the bending stiffness of the composite increases with increasing overlap length. For this reason, after the impact tests, how these effects influence the flexural behaviors of the impacted composite lap joints was also investigated. The flexural loads of the impacted and non-impacted composite single-lap joints were determined and compared with each other. It is shown that the residual flexural loads after impact increase with increasing overlap lengths but decrease with increasing impact energy.

Research paper thumbnail of Buckling behaviors of the impacted composite plates

Science and Engineering of Composite Materials, 2014

ABSTRACT The aim of this experimental study is to investigate the buckling behaviors after impact... more ABSTRACT The aim of this experimental study is to investigate the buckling behaviors after impact of the composite plates. The increasing impact energies, which ranged from approximately 3-15 J, are performed at three different impact points of the composite plates having three different thicknesses until vicinity of the penetration threshold of specimens. After the impact tests, the effects of the different impact points, energy levels, and thickness on the buckling behaviors of the impacted specimens are investigated. Also, compared with nonimpacted specimens, the buckling loads are presented nondimensionally. As expected, the lowest critical buckling load occurs in thin plates impacted at the center point. The critical buckling loads become more stable both by increasing number of layers and in the impact points that are away from the center.

Research paper thumbnail of Elastic–plastic stress analysis of rotating functionally graded discs

Thin-Walled Structures, 2015

In this study, elastic-plastic stress analysis of Functionally Graded (FG) discs subjected to con... more In this study, elastic-plastic stress analysis of Functionally Graded (FG) discs subjected to constant angular velocity is investigated. Yielding behavior of the disc material is considered to be non-work hardening case. Elasticity modulus, density and yield strength of the disc vary radially according to a power law function. To see the distribution of the plastic region, different angular velocities are taken into consideration for such an analysis. Radial and tangential stress components are obtained for the angular velocities and gradient parameters. It is seen that the results obtained from analytical and numerical (ANSYS s) solutions are in good agreement.

Research paper thumbnail of Vibration behavior of a radially functionally graded annular disc with variable geometry

Science and Engineering of Composite Materials, 2014

In this study, the free vibration behavior of an annular disc made of functionally graded materia... more In this study, the free vibration behavior of an annular disc made of functionally graded material (FGM) with variable geometry is investigated. The elasticity modulus, density, and thickness of the disc are assumed to vary through the radial direction according to the power law so that the effects of their indexes on the natural frequency of the disc are investigated. The Poisson’s ratio is assumed as a constant. The natural frequencies of the disc are calculated for various boundary conditions by using classical plate theory, and the various types of mode shapes, which are described by the number of nodal diameters and nodal circles, are also discussed. Moreover, the effects of the ratio of the inner radius to the outer radius on the natural frequency are also considered. It is found that in order to increase the natural frequency, the elasticity modulus and thickness should be increased at the inner surface, whereas density should be increased at the outer surface. The natural fr...

Research paper thumbnail of Thermal Stress Analysis of Curvilinearly Orthotropic Rotating Discs

Journal of Thermoplastic Composite Materials, 2007

This study deals with stress analysis on orthotropic rotating annular discs subjected to various ... more This study deals with stress analysis on orthotropic rotating annular discs subjected to various temperature distributions, such as uniform, linearly increasing and decreasing with radius temperatures. Tangential and radial stresses in a rotating disc under the three different temperature profiles are plotted in figures. With the increasing temperature, the tangential stress component decreases at the inner surface whereas it increases at the outer surface, and the radial stress component reduces gradually for all the temperature distributions. The magnitude of the tangential stress component is higher than that of the radial stress component for all the discs under the lower temperatures of the temperature distributions. But, when the temperature is further increased, the tangential stress component decreases more at the inner surface. The radial displacement is also calculated analytically and has higher value at the outer surface than that of the inner surface for all the tempera...

Research paper thumbnail of Three-dimensional Buckling Analysis of Thermoplastic Composite Laminated Plates with Single Vertical or Horizontal Strip Delamination

Journal of Thermoplastic Composite Materials, 2004

... load, boundary condi-tions and symmetrical model geometry. It can be said that there will not... more ... load, boundary condi-tions and symmetrical model geometry. It can be said that there will not be important effects of the contact elements in this type of buck-ling analysis. Furthermore, this case has been also examined by ...

Research paper thumbnail of Thermal Elastic–Plastic Stress Analysis of Aluminum Metal–Matrix Composite Laminated Plates Under a Parabollically Temperature Distribution

Journal of Reinforced Plastics and Composites, 2004

In this study, a thermal elastic–plastic stress analysis is carried out on steel-fiberreinforced ... more In this study, a thermal elastic–plastic stress analysis is carried out on steel-fiberreinforced aluminum metal–matrix composite laminated plates fixed at all edges. Temperature is chosen to vary parabollically. It is zero and T0 on the middle axis and at the upper–lower surfaces, respectively. The solution is executed for symmetric cross-ply (0° /90°)2 and angle-ply (30° / -30°)2, (45° / -45°)2, (60° / -60°)2 laminated plates. The elastic–plastic solution is carried out for small plastic deformations. The Tsai–Hill Theory is used as a yield criterion. Residual stress distributions along the thickness of the plates are obtained. All the residual stress components are in static balance with respect to middle plane of the laminates since they are symmetric in opposite signs.