Ramazan Karakuzu

The response of laminated composite plates under low-velocity impact loading

Abstract This paper is concerned with evaluation of the in-plane dimensional effect of fiber-reinforced laminated composites under low-velocity impact. (0/90/0/90) s oriented cross-ply E-glass/epoxy laminates studied were manufactured and all of the material parameters of laminated composite materials were measured experimentally. The impact testing was conducted with a specially developed vertical drop-weight testing machine. Impact tests were performed at impactor masses of 135 and 2600 g and an impact velocity of 3 m/s. The studies were carried out on plate dimensions of 150 mm ×150 mm , 150 mm ×100 mm and 150 mm ×50 mm with two opposite sides clamped and the other two free and impact load applied at the center of each plate. A numerical simulation was performed using 3DIMPACT transient dynamic finite element analysis code for calculating stresses and contact forces of the composite plates during impact along with a failure analysis for predicting the threshold of impact damage and initiation of delaminations.

Progressive failure analysis of pin-loaded carbon–epoxy woven composite plates

Abstract The present investigation deals with the failure strength and failure mode of a pinned-joint carbon–epoxy composite plate of arbitrary orientations. The main objective is to investigate the possibility of predicting the properties of the joint from the properties of the material measured with standard tests. The failure load and the failure mode are analysed numerically and experimentally. A computer program developed for such an analysis is used to calculate the failure load, the failure mode, and the propagation of failure of plate with different fiber orientation, different material properties and different geometries. Hoffman and Hashin failure criteria are used in failure analysis. Experimental results concerning damage progression and ultimate strength of the joint are obtained and compared with predictions. A good agreement between experimental results and numerical predictions is obtained.

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.

Exact solution of elasto-plastic stresses in a metal-matrix composite beam of arbitrary orientation subjected to transverse loads

Abstract An analytical elasto-plastic stress analysis is presented for a metal-matrix composite beam of arbitrary orientation subjected to a single transverse force applied to the free end of the beam and a uniformly distributed load. The material is assumed to be perfectly plastic in the elasto-plastic solution. A composite consisting of stainless-steel-reinforced aluminum was produced for this work. Sample problems are given for various orientation angles. Elastic, elastoplastic and residual normal and shear stresses are calculated. The location of the elasto-plastic boundary of the beam is obtained according to the x coordinates of the beam.

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.

Failure Analysis of Two-Dimensional Carbon-Epoxy Composite Plate Pinned Joint

The aim of this study is to investigate failure strength and failure mode of a mechanically fastened carbon-epoxy composite plate of arbitrary orientation. The failure load and the failure mode are analyzed numerically and experimentally. The numerical method includes two steps. First, the stress distribution in the plate is calculated by the use of finite-element method. Second, the failure load and the failure mode are predicted by means of Tsai-Hill and fiber tensile-compressive failure criteria. A computer program was developed which can be used to calculate the failure load, the failure mode, and the propagation of failure. The distance-to-diameter, E/D , and width-to-diameter, W/D , ratios in the plate are changed from 1 to 5 and 2 to 5, respectively. It is found that full bearing strength is developed when E/D and W/D ratios are equal to or greater than 4.

The strength of pinned joints in laminated composites

Abstract An investigation was performed to study the response of pin-loaded laminated composites. Tensile tests were performed on E/glass-epoxy composites for two different ply orientations such as [0/±45]s and [90/±45]s. For each ply orientation, 20 different geometries were chosen. The major focus of the study was to characterize the failure mechanisms and to evaluate the effect of geometric dimensions on the bearing, shear-out and net-tension strengths of pinned joints. For this purpose, the specimens were tested to find first failure and final failure load. In addition, by using finite element code PDNLPIN, a static progressive failure analysis was performed. The effect of the material non-linearity was taken into account on the mathematical forms. Comparisons were made between the test data and the results of the model and these showed good agreements.

Failure Strength of Woven Glass Fiber-Epoxy Composites Pinned Joints

In this paper, mechanical behavior and damage development of pin-loaded woven glass fiber-epoxy composites have been observed numerically and experimentally. Parametric studies have been performed to evaluate the effects of joint geometry and ply orientation on the failure strength and failure mode of composite laminates with a pin-loaded hole. For this purpose, a finite element program has been developed. The failure analysis was based on Hashin and Hoffman criteria that were applied at the ply level. The results (with Hashin and Hoffman criteria) were compared to each other. To verify to the numerical predictions of mechanical behavior, a series of experiments was performed with two different material configurations ([(0/90)3]S [(45)3]S) and twenty different geometries. The numerical and experimental results were compared and discussed. A good agreement between experimental results and numerical predictions was obtained.

Dynamic Characteristics of Laminated Woven E-Glass–Epoxy Composite Plates Subjected to Lowvelocity Heavy Mass Impact:

The main goal of this study is to examine the size effects including both in-plane dimensional and thickness effects for laminated woven E-glass–epoxy composite subjected to low velocity heavy mass impact. The studies have been carried out with plate dimensions of 150 × 150 mm, 150 × 100 mm and 150 × 50 mm for in-plane dimensional effect. Two nominal thicknesses with averages of 1.4 and2.8 mm are used for studying the thickness effect. The impact testings are conducted with a vertical drop-weight testing machine developed in the department laboratory. Affixed to the drop-weight device, a piezoelectric force transducer, localized in the hemispherical impactor nose, yields the complete force versus time history of impact event. Impact tests are performed at increasing impact velocities 1, 2 and 3m/s and impactor mass of 2.6 kg on clamped plates. A numerical evaluation of these specimens is also carried out by using 3DIMPACT transient dynamic finite element analysis code. The contact forces between the impactor and the composite plate as functions of time, transient stresses during impact and the predicted delamination sizes of composites are found numerically.

Elastic–plastic behavior of woven-steel-fiber-reinforced thermoplastic laminated plates under in-plane loading

Abstract This paper deals with elastic–plastic stress analysis of thermoplastic laminated composite plates reinforced with woven steel fibers and containing circular holes under in-plane static loading. Residual stresses and propagation of plastic zones are obtained in simply supported symmetric and antisymmetric laminated composite plates by using a nine-node Lagrangian finite-element method. First-order shear deformation theory was used as an equivalent single-layer laminate theory for small deformations so that large plastic strains are not allowed to occur. A modified Newton–Raphson method is used as an iterative technique for determining the non-linear behavior of the material after yielding. After yielding the load is increased by means of many load steps, 0.01 MPa at each step, to follow the stress/strain curve more accurately. Mechanical properties of a layer were obtained experimentally.