Thermoplastic polyurethane materials are widely used in automotive, clothing, electrical and electronics, medical, construction, machine industry due to excellent physical and chemical properties. ...Thermoplastic polyurethane materials combustion and resistance to high temperature characteristics are poor. Additives and fillers are added into the polyurethane matrix to improve those properties. Particularly adding these agents as a flame retardant are affect mechanical properties of polyurethane materials. Therefore, it is important to determinate the mechanical properties of these materials. In this study, 5% by weight of the thermoplastic polyurethane material, aluminium tri hydroxide (ATH, (Al2O3 3H2O)) and magnesium hydroxide (MgOH, (Mg(OH)2)) were added. Ammonium polyphosphate (APP) as an intumescent flame retardant with inorganic flame retardants were added to increase the flame resistance of produced composite structure. Tensile test, tear test, hardness and Izod impact tests were made and compared of those produced composites. As a result of experiments the addition of ATH has lowered the tensile strength and tear strength contrast to this the addition of MgOH has improved those properties. Hardness and Izod impact test results were showed that both of the additives have no negative effect.
With the advanced technology of our time comes an increased need for high quality materials. The conventional engineering materials are no longer adequate to suit the needs of the manufacturing ...process. Therefore, there is constant growth in the fields of the use of composite materials formed by the combination of two or more materials. Also various difficulties occur in the field where the composite materials are used. The systems which will be used both in the manufacturing process and in engineering designs are composed of more than one component. Therefore, the components should be jointed for the system designed. These joints are enabled with mechanical and bonding techniques. In this study, mechanical joints made with a joint lock having I profile have been recommended for use instead of the bonding technique in the butt joint of the composite plates. Load-carrying capacities of the locks of different dimensions formed with the exchange of basic geometric parameters that characterize I profile joint lock and its effects on the first damage have been analyzed experimentally and numerically. Determining the optimal joint with the best strength has also been conducted. The composite structure has been prevented from complete damage by the determination of the initial damage that may occur on I profile joint lock. Thus, the lifespan of the composite structure has been increased with the exchange of the lock component.
In this paper, fatigue life of the repaired cracks in 2024-T 3 aluminum with bonded patches made of unidirectional composite plates has been investigated experimentally and numerically for ...hygrothermal effect. The problem is handled in plane stress and Mode I condition. In the experimental study the mechanical properties of the aluminum plate and patch materials are determined and fatigue experiments are conducted. The results obtained from these experiments and numerical solutions are compared. Thus the reliability of the numerical solution has been proven. For all conditions, numerical solutions have been made and stress intensity factor (
K
I) and fatigue life are calculated. Different plate and patch thicknesses are also considered in the experiments.
In this study, the elastic stress analysis of a hollow disk made of functionally graded materials was subjected to a linearly increasing temperature distribution. These disks have many applications ...in the aerospace industry, such as gas turbines and break disks. Their life cycle can increase when the stress components are minimized. A functionally graded (FG) disk with variable thickness under a linearly increasing temperature distribution is considered in this paper. The calculation program was prepared by the authors using MATLAB 7.1
®
. The changes in stresses and displacements according to both gradient parameters and thickness profiles were investigated and presented. The results show that gradient parameters and thickness profiles play an important role in determining the thermal responses of FG disks and in determining an optimal design of these structures.
In this study, the elastic stress analysis of a composite disc with aluminium matrix subjected to a linearly-increasing temperature distribution has been carried out. The values of tangential and ...radial stress components that have occurred under the effect of the temperature from the inner surface of the disc towards the outer surface have been obtained by two different methods, numerical and analytical. In the analytical analysis, a computer program has been developed to get the values of thermal stresses. But in the numerical study carried out with the finite-element method, Abaqus 6.8 package program has been used. As a result of these analyses, it has been observed that the stress values obtained from both methods support each other. It has been determined under this temperature distribution that tangential stress components are always on the condition of compression in the inner surface of the disc and of tensile in the outer surface. It has also been found out that radial stress components are always in the state of tensile along the whole profile of the disc. Finally, the stress analysis of the same composite disc subjected to this temperature distribution, but with a reduced mass, has also been examined numerically.
This study was designed to analyze the load-carrying capacities of composite structures connected face-to-face by a butterfly coupling component experimentally and numerically without adhesive. The ...results of the experimental studies were supported with numerical analysis. In addition, the butterfly coupling component was developed geometrically with a view to the results of the numerical and experimental studies. The change in the load-carrying capacity of the improved butterfly coupling components was analyzed numerically and experimentally to obtain new results. Half-specimens and butterfly-shaped lock components were cut with a water jet machine. Experiments and analyses were conducted to analyze the effects of coupling geometry parameters, such as the ratio of the butterfly end width to the specimen width (w/b), the ratio of the butterfly middle width to the butterfly end width (x/w), and the ratio of the butterfly half height to the specimen width (y/b). It was intended to determine the damage in the butterfly before any damage to the composite structure and to increase the service-life span of the composite structure with the repair of the butterfly lock. As a result of this study, it was determined that the geometrical fixed ratios (w/b) and (x/w) were 0.4 and 0.2 at 0.4 of (y/b) according to the experimental and numerical studies with basic and modified models.
In this study, the elastic stress analysis of annular discs made of functionally graded materials (FGMs) subjected to both uniform pressures on the inner surface and a linearly decreasing temperature ...distribution has been carried out. The elasticity modulus and thermal expansion coefficient of the discs are assumed to vary radially according to power law functions and Poisson's ratio is kept constant. Analytical solutions for the elastic stress in annular discs are obtained under plane stress assumption. Calculation programs were prepared by authors using MATLAB 7.1. The change of the stresses, displacements, elasticity modulus and thermal expansion coefficient according to the gradient parameters were investigated and presented.
In this study, the effects of location, size and number of delaminations, boundary conditions, orientation angles and stacking sequences on the natural frequency of laminated composite beams are ...investigated experimentally, analytically and numerically. Two-dimensional finite element models of the delaminated beams are obtained using ANSYS (Finite ElementMethod Code). The analytical method is developed using Euler-Bernoulli beam theory. Then, analytical results are compared with the results available in the literature and the numerical and experimental results in the present study. It has been seen that all results obtained are very close to each other. It is shown that the natural frequencies decrease when sizes and numbers of edge and middle delaminations in the beam increase, and the location of the delamination is also very important.The first natural frequency value of beam of 0°/90°
8
is found to be the highest as compared to the beamswith angles 30°
16
and 60°
16
. However, the natural frequency values in the beams that have the angle-ply of θ
16
are lower than those of θ/−θ
8
, (θ/−θ)
4
s
and (θ/−θ)
s
4
.
In this article, fatigue of cracked 2024-T3 aluminum plate repaired with composite patches has been experimentally investigated. In the study, different aluminum thicknesses, numbers of patch layers, ...and temperatures have been taken into account. The problem has been considered under plain stress and Mode I conditions. First, mechanical properties of the samples used in the experiments have been determined. Then, cracked samples were bonded with composite patches and crack propagation and fatigue experiments have been conducted. From the experimental results, it has been shown that varied temperatures play an effective role on the fatigue life.
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