Onur Sayman

Elasto-plastic finite element analysis of orthotropic rotating discs with holes

The elasto-plastic stress analysis of orthotropic rotating discs with holes has been carried out by the finite element method (FEM). An isoparametric rectangular element with nine nodes has been chosen and the Lagrange polynomial has been used as interpolation function. Steel-aluminium composite has been manufactured by upsetting under the pressure and the temperature. Mechanical properties and yield strengths of composite material have been obtained experimentally by using a strain gauge in the tensile testing machine. The expansions of plastic regions have been illustrated for various cases. Residual stresses and tangential stresses have been shown on the elasto-plastic boundaries of the disc. The limit of angular velocities of the orthotropic disc have been increased by using tangential residual stresses and tangential stresses in the disc subjected to the centrifugal force.

Failure analysis of pin-loaded aluminum-glass-epoxy sandwich composite plates

Abstract The aim of this study is to investigate failure load and failure mode in an aluminum–glass–epoxy sandwich composite plate, with a circular hole, which is subjected to a traction force by a pin. To evaluate the effects of joint geometry and fiber orientation on the failure strength and failure mode, parametric studies were performed experimentally. The end distance to diameter (E/D), and width to diameter (W/D) ratios in the plate were changed from 1 to 5 and 2 to 5, respectively. Experimental results show that the first failure load and ultimate failure load increase by increasing E/D and W/D ratios, and when these ratios are equal or greater than 4, full bearing strength occurs.

ELASTIC-PLASTIC FINITE ELEMENT ANALYSIS OF METAL MATRIX PLATES WITH EDGE NOTCHES

Abstract A two-dimensional finite element program has been developed for elastic-plastic analysis. Isoparametric quadrilateral element with four nodes is used and Lagrange polynomial has been chosen as interpolation function. In the finite element solution, an initial stress method (modified Newton-Raphson method) is used. Residual stresses have been shown in figures and the spread of plastic zones has been illustrated for steel-aluminum composite plates with edge notches.

Elasto-plastic stress analysis in stainless steel fiber reinforced aluminum metal matrix laminated plates loaded transversely

Metal matrix composites provide new materials with superior properties. They give high strength and stiffness. In this study, a stainless steel fiber reinforced aluminum metal matrix laminated simple supported plate is loaded transversely. Elasto-plastic stress analysis is carried out in the laminated plate by using finite element technique. The expansion of plastic zone and residual stresses are determined in the symmetric and/or antisymmetric cross-ply and angle-ply laminated plates for small deformations. Iteration numbers are chosen as 100, 150 and 200. The yield points in symmetric laminates are higher than those in antisymmetric laminates.

Elastic–plastic stress analysis and expansion of plastic zone in clamped and simply supported aluminum metal–matrix laminated plates

Abstract An elastic–plastic stress analysis and the expansion of plastic zone in layers of stainless steel fiber-reinforced aluminum metal–matrix laminated plates are studied by using Finite Element Method and First-order shear deformation theory for small deformations. The plate is meshed into 64 elements and 289 nodes with simply supported or clamped boundary conditions. Laminated plates of constant thickness are formed by stacking four layers bonded symmetrically or antisymmetrically. It is assumed that the laminated plates are subjected to transverse uniform loads. Loading is gradually increased from yield point of the plate as 0.0001 MPa at each load step. Load steps are chosen as 100, 150 and 200.

An elastic-plastic stress analysis in a thermoplastic composite cantilever beam

Abstract In the present study an analytical elastic–plastic stress analysis is carried out for a low-density homogeneous polyethylene thermoplastic cantilever beam reinforced by Cr–Ni steel fibers. The beam is loaded by a constant single force at its free end. The expansion of the plastic region and the residual stress component of σ x are determined for 0, 15, 30 and 45° orientation angles. Yielding begins for 0 and 45° orientation angles at the upper and lower surfaces of the beam at the same distances from the free end. However, it starts first at the upper surface for 15 and 30° orientation angles. The elastic–plastic analysis is carried out for both the plastic region which spreads only at the upper surface and the plastic region which spreads at the upper and lower surfaces together. The residual stress components are obtained after releasing the external force. The distributions of the residual stress components of σ x and τ xy are also determined. The intensity of the residual stress component is maximum at the upper and lower surfaces of the beam, but the residual stress component of τ xy is maximum on or around the x -axis. The beam can be strengthened by using the residual stresses. The distance between the plastically collapsed points and the free end is calculated for the same load in the beam for 0, 15, 30 and 45° orientation angles.

Elasto-plastic stress analysis of aluminum metal-matrix composite laminated plates under in-plane loading

Abstract The study presents an elasto-plastic stress analysis of symmetric and antisymmetric cross-ply, angle-ply laminated metal-matrix composite plates. Long stainless steel fiber reinforced aluminum metal-matrix composite layer is manufactured by using moulds under the action of 30 MPa pressure and heating up to 600°C. A laminated plate consists of four metal-matrix layers bonded symmetrically or antisymmetrically. The first-order shear deformation theory and nine-node Lagrangian finite element is used. The in-plane load is increased gradually.

An elastic-plastic stress analysis of thermoplastic composite beams loaded by bending moments

Abstract In this study, an elastic–plastic stress analysis is carried out on a high-density thermoplastic-based composite cantilever beam loaded by a bending moment at the free end. The composite beam is reinforced unidirectionally by steel fibers, at 0°, 30°, 45°, 60° and 90° orientation angles. An analytical solution is performed for satisfying both the governing differential equation in the plane stress case and boundary conditions for small plastic deformations. The solution is carried out under the assumption of the Bernoulli–Navier hypotheses. It is found that the intensity of the residual stress component of σx is maximum at the upper and lower surfaces or at the boundary of the elastic and plastic regions. The composite material is assumed to be strain-hardening. The Tsai–Hill theory is used as a yield criterion. The displacement components are found in the elastic region.

Elasto-plastic stress analysis in simply supported thermoplastic laminated plates under thermal loads

Abstract In this study, an elasto-plastic stress analysis is carried out on symmetric cross-ply [0°/90°]2 and symmetric angle-ply [30°/−30°]2, [45°/−45°]2, [60°/−60°]2 thermoplastic laminated plates. Laminated composite plates are simply supported and subjected to constant temperature change through the thickness. An analytical solution is performed for satisfying thermoelasto-plastic stress/strain relationships and boundary conditions for small plastic deformations. The composite materials are assumed to be perfectly plastic. The Tsai-Hill theory is used as a yield criterion. Residual stress components, σ x r and σ y r , for cross-ply laminated plates have some magnitudes but τ xy r are zero. The magnitudes of residual stress components increase gradually depending on the temperature increment. For symmetric angle-ply laminated plates, residual stresses are found zero except τ xy r .

An elastic/plastic solution for a thermoplastic composite cantilever beam loading by bending moment

Abstract In this study, an elastic/plastic stress analysis is carried out for a thermoplastic composite cantilever beam loaded by a bending moment at the free end. The composite beam is reinforced by woven steel fibers, at 0, 15, 30 and 45° orientation angles. An analytical solution is performed for satisfying both the governing differential equation in the plane stress case and boundary conditions for small plastic deformations. The solution is carried out under the assumption of the Bernoulli–Navier hypotheses. It is found that the intensity of the residual stress component of σx is a maximum at the upper and lower surfaces. The composite material is assumed to be as hardening linearly. The Tsai–Hill theory is used as a yield criterion.