Halil Aykul

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.

The three-dimensional finite element analysis of fixed bridge restoration supported by the combination of teeth and osseointegrated implants.

This study investigated the designs of osseointegrated prostheses in cases of free-end partial edentulism using comparative stress interpreted with the three-dimensional finite element method. Three free-end fixed osseointegrated prostheses models with various connection designs (ie, rigidly connected to an abutment tooth and an implant, rigidly connected to an implant and two abutment teeth, and rigidly connected to an implant and three abut- ment teeth) were studied. The stress values of the three models loaded with vertical, buccolingual, and linguobuccal directions at 30° angled to vertical axis forces were analyzed. When the fixed partial denture was connected to the three natural abutment teeth and an implant, the lowest levels of stress in the bone were noted.

Elasto-Plastic Stress Analysis of Aluminum Metal Matrix Laminated Plates with a Circular Hole under Transverse Loading

Metal-matrix composites provide new materials with superior properties. They give high strength and stiffness and fatigue properties. In this study, a stainless steel fiber reinforced aluminum metal-matrix laminated simply supported plate with a circular hole is loaded transversely. Elastic, elasto-plastic and residual stresses are calculated in the symmetric and/or antisymmetric cross-ply and angle-ply laminated plate for small deformations by using finite elements method. Load steps are chosen 200, 400 and 600. Isoparametric quadrilateral element with nine node is developed for the elasto-plastic analysis. Metal-matrix composite laminated plate is manufactured by using moulds under the action of 30 MPa and heating up 600°C. The first-order shear deformation theory is used in the study.

Residual stress analysis and expansion of plastic zone in clamped supported aluminum metal-matrix laminated plates with a circular hole under transverse loading

In this paper, a residual stress analysis and expansion of plastic zone in metal-matrix composite laminated plates with a circular hole are studied by using Finite Element Method. Aluminum metal-matrix and steel fibers are used to produce the composite plates by using mould. Mathematical formulation is given for the elastic-plastic stress analysis of a laminated plate under transverse loads for small deformation. The first-order shear deformation theory is used in this study. The expansion of plastic zone is illustrated for 300, 600 and 900 loading steps.

Residual Stress Analysis of Aluminum Metal Matrix Composite Laminated Plates with a Square Hole

Metal matrix composites provide new materials with superior properties. They give high strength and stiffness. In this study, a stainless steel reinforced aluminum metal matrix laminated simple supported plate with a square hole is loaded transversely. Elastic, plastic, and residual stress analysis are calculated in the symmetric and antisymmetric cross-ply and angle-ply laminated plates for small deformations by using finite elements method. First-order shear deformation theory and nine nodes Lagrangian finite element are used. Load steps are chosen at 200, 400, and 600. Mechanical properties of a layer are obtained experimentally. The change of the residual stresses σ x and σy from square hole to simple supported edge are shown as figures.

An Elastic-Plastic Stress Analysis of Woven Ni-Cr Reinforced Thermoplastic Composite Cantilever Beam

In the present study an analytical elastic-plastic stress analysis is carried out for a low-density homogeneous polyethylene thermoplastic cantilever beam reinforced by Ni-Cr steel fibers. The beam is loaded by a constant single force at its free end. The expansion of the region and the residual stress component of σx are determined for 0°, 15° , 30° and 45° orientation angles. For 0 ° and 45° orientation angles yielding begins at the upper and lower surfaces of the beam, at the same distances from the free end. However, for 15° and 30° orientation angles it starts first at the upper surface. 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 of σx and τxy 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 point and the free end is calculated for the same load in the beam for 0 °, 15°, 30° and 45° orientation angles.

Impact response of sandwiches with open-cell casting metal foam and GFRP skins

Abstract The main advantage of using sandwich structures is their high strength, high energy absorbing capacity and high bending stiffness to weight ratio. Therefore, they are unique for the applications where the light-weight design philosophy is a crucial aspect. While sandwich structures with polymeric foams have been applied for many years, recently there is a growing interest on a new generation composite sandwiches with metallic foam core. In this study, the influence of pores per inch (ppi) of the foam on low-velocity impact response of the entire panel has been investigated. The glass fibre reinforced plastic (GFRP) skins produced by vacuum bagging technique in the study were easily bonded to the foam surfaces using a commercial adhesive in order to combine the composite sandwich panel. The low-velocity impact tests are performed to the sandwiches with the combination of two different magnesium (Mg) alloy foams (having 10 pores per inch (ppi) and 20 pores per inch), and carried out by a drop test machine with different values of impact velocity ranging from 1 to 10 m/s in order to analyse its effect. The main results of the impact tests are: force-displacement curves, peak force values, absorbed energy and influence of impact velocity.

Residual Stress Analysis And Expansion of Plastic Zone in Simple Supported and Clamped Supported Woven Ni—Cr Reinforced Thermoplastic Matrix Composite Laminated Plates

In this study, a residual stress analysis is carried out on symmetric cross-ply and angle-ply thermoplastic simple supported and clamped supported laminated plates for transverse loading. Low density polyethylene thermoplastic matrix (LDPE) and woven Ni—Cr fibers are used to produce the composite plates by using molds. First order shear deformation theory and nine nodes Lagrangian finite element are used. Mathematical formulation is given for the elasto-plastic stress analysis of a laminated plate for small deformations. Yield points and stresses are obtained for symmetric simple supported and clamped supported laminated plates. Residual stresses in thermoplastic plates are given in the tables. The expansion of plastic zones is illustrated for 50, 100 and 150 loading steps. Yield points and the expansion of plastic zones are compared for different plates. Mechanical properties of a layer are obtained experimentally.

Elastoplastic Stress Analysis in a Woven Ni-Cr Reinforced Thermoplastic-matrix Composite Laminated Plates under Transverse Loading

In this study, an elastoplastic stress analysis is carried out on the symmetric and antisymmetric cross-ply and angle-ply thermoplastic-laminated plates for transverse loading. A low density polyethylene (LDPE) thermoplastic-matrix and woven Ni—Cr fibers are used to produce composite plates by using molds. A first-order shear deformation theory and a nine-node Lagrangian finite element are used. Mathematical formulation is given for the elastoplastic stress analysis of a laminated plate for small deformations. The yield points and stresses are obtained for symmetric and antisymmetric clamp supported laminated plates with a square hole. The residual stresses in the thermoplastic plates are given in the tables. The expansion of plastic zones is illustrated for 200, 350, and 500 loading steps. The yield points and expansion of plastic zones are compared for different plates. The mechanical properties of a layer are obtained experimentally. The intensity of the residual stress components is maximum near the square hole and clamped supports.

Residual Stress Analysis of Clamped Supported Thermoplastic Matrix Composite Laminated Plates Under Transverse Loading

Residual stress analysis is carried out in a thermoplastic composite laminated plate for transverse loading. Low-density polyethylene thermoplastic matrix (LDPE) and steel fibers are used to produce the composite plates by using molds. The first order shear deformation theory and nine nodes Lagrangian finite element is used. Mathematical formulation is given for the residual stress analysis of a laminated plate for small deformations. Yield points and stresses are obtained for symmetric and antisymmetric laminated plates with a circular hole. Residual stresses in plates are given in tables. The expansion of plastic zones is illustrated for 500, 750 and 1000 load steps. Yield points and the expansion of plastic zones are compared for different plates with a circular hole. Mechanical properties of a layer are obtained experimentally.