Nurettin Arslan

Failure Analysis of Laminated Composite Plates with Two Parallel Pin-loaded Holes

The aim of this study is to research the failure loads and failure modes of laminated woven-glass—polyester composite plates with two parallel circular holes, which are subjected to traction forces by two rigid pins. The failure behavior of two parallel pin-loaded composite plates has been observed both experimentally and numerically with different geometries and fiber orientations. While the plate width to hole diameter ratio (W/D) was held constant; the distance from the free edge of the plate to hole diameter ratio (E/D) was changed from 1 to 5, and the distance between two parallel holes to hole diameter ratio (M/D) was varied from 2 to 5. Two different ply rientations were also investigated as [0°]8 and [0°2=60° 2/]s. In a numerical study, a three-dimensional finite element method (FEM) was used with the assistance of a LUSAS 13.6 finite element analysis program. Good agreement has been shown between experimental and numerical results.

Elasto-plastic behavior of thermoplastic matrix plates with rectangular hole

The elasto-plastic stress analysis of the thermoplastic matrix plates with rectangular hole is carried out by using finite elements. A two-dimensional finite element computer program is developed for elasto-plastic stress analysis. Isoparametric quadratic element with nine nodes is used with Lagrange polynomial as an interpolation function. The spreads of the plastic zones and variations of the residual stresses are obtained in different orientation angles and loads. It is shown that the path around the hole location can be designed to decrease the stress concentrations. The results are presented in diagrams and compared with some of the relevant studies in the literature.

Thermoplastic Matrix Plates in Elasto-Plastic Finite Element Analysis

A two-dimensional finite element computer program is developed for elasto and elasto-plastic analysis. The analysis of the semicircular and “U” shaped edge notched plates manufactured from steel-thermoplastic composite is made under the uniform tension loads. Isoparametric quadrilateral element with four and nine nodes is used with Lagrange polynomial as an interpolation function. An initial stress method (modified Newton-Raphson) is used to determine elasto-plastic stresses in the finite element solution. Distribution of the plastic regions near the notch and variations of residual stresses are investigated in different orientation angles and loads for steel-thermoplastic composite plates with edge notches.

Prediction of the Residual Stresses and Expansion of Plastic Zones in Simply Supported Thermoplastic Composite Laminated Plates Subjected to Transverse Loads

In the present study, the residual stresses and expansion of the plastic zones in simply supported thermoplastic composite laminated plates under uniform transverse loads are given by using FEM. Elastic-plastic stress analysis is carried out for small deformations. Low density homogeneous polyethylene (thermoplastic) and woven stainless steel are used as matrix and fiber materials, respectively. The effect of the reinforcement angle varying from [0 / 15]2 to [0 / 90]2 for [0 /]2 and from [15 / 15]2 to [45 / 45]2 for [/]2 on the residual stresses and the spread of plastic zones are presented. In this analysis, the first-order shear deformation theory is used. The transverse loads are gradually increased from the yield point of the plate by 0.0001 MPa at each load step. Load steps are chosen as 100, 200, 300, 400 and 500. The laminated plates of constant thickness are formed by stacking four layers bonded symmetrically or antisymmetrically.

An elastic-plastic stress analysis of a woven reinforced steel fiber thermoplastic composite cantilever beam subjected to transverse uniform loads on the upper surface

In this study, an elastic-plastic stress analysis is carried out for a thermoplastic cantilever beam. This composite beam consists of woven Cr-Ni steel fibers and a low-density homogeneous polyethylene matrix, and is loaded uniformly. The Tsai-Hill yield theory is used for an analytical solution. The expansion of the plastic region and the residual stress component of x are determined for 0, 15, 30, 45, 60, and 90 orientation angles. The 45 orientation angle, which gives symmetrical values, represents the mean reinforcement angle because of the reinforcement type. The plastic region starts at the upper surface of the beam for 30 orientation angle. The intensity of the residual stress component of x is maximum at the upper and lower surfaces of the beam.

An elastic-plastic stress analysis in a unidirectional reinforced steel fiber thermoplastic composite cantilever beam loaded by a single force at the free end

In this study an elastic-plastic analysis is carried out in a unidirectional reinforced thermoplastic composite cantilever beam loaded by a constant single force at its free end. The composite beam consists of stainless steel fiber and low-density homogeneous polyethylene matrix. An analytical solution is performed for satisfying both the governing differential equation in the plane stresses case and boundary conditions for small plastic deformation. The composite material is assumed to be hardening linearly. The Tsai-Hill theory is used as a yield criterion. The intensity of the residual stress components of x is at the maximum at the upper or lower surfaces of the beam.

Elastic–Plastic Stress Analysis in Aluminum Metal–Matrix Composite-laminated Plates ([0°/θ°]2) Under Transverse Uniformly Distributed Load

In this paper, an elastic–plastic stress analysis is carried out in unidirectional reinforced steel–aluminum composite-laminated plates under transverse loading and simply supported conditions. For the elastic–plastic stress analysis, the mathematical formulation is given for small deformations. Finite Element Method and first-order shear deformation theory are used. A finite element computer program is developed for stress analysis. The laminated plates of constant thickness are manufactured by stacking four layers bonded symmetrically or antisymmetrically. The residual stress components and yield points are calculated for each layer and compared with different reinforced layers. The location and the expansion of the plastic zones are obtained according to loading gradually increased from yield point as 0.0001 MPa at each load step. The load capacity of the laminated plate increases by means of the residual stresses.

The Effect of Curing Conditions and Fiber End Shapes on the Mechanical Properties of Composites

The study consists of two main experimental parts. The aim of the first part of the study is to investigate the effects of the straight-short steel fibers and different curing conditions on the mechanical properties of the selected composite specimens. For this purpose, unreinforced (no fiber) specimens cured at room temperature (∼20°C) and the straight-short steel fiber reinforced polyester—calcite composite specimens cured at room temperature and at different curing conditions of 40, 80, and 120°C for 4, 8, and 12 h, have been subjected to tensile tests. In the second part of the study, unreinforced specimens and polyester—calcite composite specimens with straight-short, woven, and three different end shaped fibers cured at room temperature have been tested according to the four-point bending test procedure so as to obtain the effects of the end shapes on the mechanical properties of the composite specimens.

İKİ EKSENLİ YÜKLENMİŞ VE ORTASINDA ELİPTİK DELİK BULUNAN PLAKANIN DELİK GEOMETRİSİNE VE EĞİMİNE GÖRE GERİLME YOĞUNLUĞU FAKTÖRÜNÜN HESAPLANMASI

Sonlu bir plaka da bulunan delik v.b. sureksizlikler gerilme altinda iken delik civarinda daha fazla gerilmeyigilmasina neden olmaktadir. Iki eksenli gerilme durumu icin plakadaki farkli gerilme oranlarina gore gerilmeyogunlugunun degisimi elde edilmistir. Elips deligin uzun kenar (2b) ve kisa kenar (2a) uzunluklarina gore plakayuzeyinde meydana gelen gerilme alani dagilimi gosterilmistir. Ayrica, farkli gerilme oranlarinda elips deligin(2a) kenar uzunlugunun plaka genisligine gore (H) maksimum gerilme degerleri sonlu elamanlar yontemikullanilarak hesaplanmistir. Plaka x-eksenine gore, elips deligin egimine gore (θ= 00,150, 300, 450 ve 900)plakada meydana gelen gerilme yogunlugu ve alan degisimi arastirilmistir.

Düşey Yükleme Altında Kompozit Tabakalı Bir Plakanın Sonlu Elemanlar Yöntemi İle Plastik Bölge Genişlemesinin ve Oluşan Gerilmenin Analizi

The aim of this work is to predict the expansion of the plastic zone and residual stresses in layers of stainless steel woven fiber-reinforced thermoplastic matrix composite laminated plates (( 0 /- 0 )2) with rectangu- lar hole. The elastic and elastic-plastic stresses are analyzed by using FEM by means of a developed computer program with FORTRAN 90. The laminated plates arranged in (( 0 /- 0 )2) configuration under uniform trans- verse loading are formed by stacking four composite layers bonded symmetrically or antisymmetrically. Loading is gradually increased from yield point of the plate as 0.0001 Mpa at each load step. The elastic, elastic-plastic and residual stress components and the expansion of the plastic zones are obtained according to the load steps, different orientation angles and rectangular hole dimensions under clamped and simply supported boundary conditions. Results showed that the maximum stress levels and the plastic zones appear the vicinity of the rec- tangular hole at the upper and lower layers.