Stress analysis in a functionally graded disc under mechanical loads and a steady state temperature distribution

Abstract.: An analytical thermoelasticity solution for a disc made of functionally graded materials (FGMs) is presented. Infinitesimal deformation theory of elasticity and power law distribution for functional gradation are used in the solution procedure. Some relative results for the stress and displacement components along the radius are presented due to internal pressure, external pressure, centrifugal force and steady state temperature. From the results, it is found that the grading indexes play an important role in determining the thermomechanical responses of FG disc and in optimal design of these structures. © 2011 Indian Academy of Sciences

Buckling behaviors of the impacted composite plates

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

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

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. © 2015 by De Gruyter

Elastic-plastic stress analysis of unidirectionally reinforced symmetric thermoplastic laminated beams loaded by bending moment

Elastic-plastic stress analysis is carried out on steel fiber reinforced thermoplastic matrix laminated beams loaded by bending moment. The beam is composed of four orthotropic layers, perfectly bonded and symmetrically arranged with respect to the x-axis. The orientation angles are chosen as (90 degrees/0 degrees)(s), (30 degrees/-30 degrees)(s), (45 degrees/-45 degrees)(s) and (60 degrees/-60 degrees)(s). The composite material is assumed to be linearly hardening, sigma(x) residual stress component is found to be highest at the upper and lower surfaces. However, when the applied bending moment is increased, the plastic region is further expanded towards middle plane from the upper and lower surfaces of the beam and so a, residual stress component is found to be highest at the elastic and plastic boundaries. The plastic flow is obtained to be maximum at the upper and lower surfaces for (30 degrees/-30 degrees)(s) orientation. The transverse displacement is obtained to be highest at the free end for (90 degrees/0 degrees)(s) orientation

An Assesment of the Impacted Composite Single-Lap Adhesive Joints

The aim of this experimental study is to investigate impact behaviors of the composite single-lap adhesive joints. The increasing impact energies, which are ranged from approximately 5 J to 30 J, are performed 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 by increase in the overlap length. An energy profiling method (EPM) is used to identify the penetration and perforation thresholds of composite lap joints. The damaged composite plates are visually inspected. Copyright © 2015 The Society of Theoretical and Applied Mechanics, R.O.C

Elastic-plastic stress analysis of rotating functionally graded discs

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®) solutions are in good agreement. © 2015 Elsevier Ltd All rights reserved

Stress analysis of functionally graded discs under mechanical and thermal loads

The analytical study deals with stress analysis of functionally graded rotating annular discs subjected to internal pressure and various temperature distributions, such as uniform T0 (reference temperature), linearly increasing Tb (outer surface temperature) and decreasing Ta (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 T0 and Tb temperatures. If Ta 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 T0 and Ta temperatures, whereas they rise along the radial section when Tb is increased. The radial displacement values in the discs subjected to uniform temperature T0 are higher compared to the discs subjected to other kind of temperature distributions. The radial displacement has higher value at the outer surface than that of the inner surface for all the temperature distributions, except for radial displacement in the reference temperature case. The stresses and displacement values in a disc under uniform temperature are compared with the values given in the literature and they are found to be consistent with each other

Stress analysis of functionally graded rotating discs: Analytical and numerical solutions

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. © 2011 The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag Berlin Heidelberg

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

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 frequency can also be increased by increasing the ratio of inner radius to outer radius. The results obtained are compared with the results of a finiteelement- based commercial program, ANSYS®, and found to be consistent with each other