Hasim Pihtili

Investigation of the wear behaviour of a glass-fibre-reinforced composite and plain polyester resin

In industrial applications, the increase in the use of composite materials means that it is necessary to know their behaviour under working conditions. Wear is an important parameter and its experimental behaviour must be known. In this study, the wear behaviour of a glass-fibre-reinforced composite and plain polyester resin are experimentally investigated for speeds of 500 and 710 rpm and at two different loads of 500 and 1000 g by the use of a block-on-disk wear tester. Wear in the experiments was determined as weight loss. The weight losses were measured after sliding distances of 235.5, 471, 706.5, 942, 1177.5, 1413, 1648.5 and 1884 mm. In addition, photographs of specimens were taken under the SEM and the wear behaviour in these photographs was investigated.

An Elastic-Plastic Stress Analysis in a Thermoplastic Composite Cantilever Beam Loaded Uniformly

In this study an elastic-plastic stress analysis is carried out on a steel fiber reinforced thermoplastic composite cantilever beam loaded uniformly at the upper surface. An analytical solution is found satisfying both the governing differential equation in two dimensional case and boundary conditions. In this solution, the intensity of the uniform force is chosen small, therefore the transversely normal stress component is neglected in comparison with the other stress components. The thermoplastic matrix is reinforced unidirectionally by steel fibers. The orientation angles of the fibers are chosen as 0°, 30°, 45°, 60° and 90°. The plastic region begins first at the upper surface of the beam for 30° and 45° orientation angles. However, it starts earlier at the lower surface for 60° orientation angle. The intensity of the normal residual stress component in the axial direction of the beam is maximum at the upper and/or lower surfaces in the beam. The intensity of the shear residual stress is maximum on or around the axial axis of the beam.

Investigation of Different Reinforced Composite Materials for Surface Roughness and Capacity of Being Drilled

In this study, drilling performance and cutting parameters with holes having different qualities, drill kinds, and drill diameters were examined in different composite materials. HSS, TIN, and carbide drills with 5, 10, and 15 mm diameter were used in drilling processes. Experiments were conducted with dry drilling at different cutting speeds of 125, 250, and 315 rpm and progresses of 0.056, 0112, and 0.16 mm/rev. Different kinds of composites with different reinforced composites were used as materials. As a result of the drilling operations, it is found that as rotation and progress speed increases, surface roughness on the processed surface increases as well. Better results in terms of surface roughness were obtained with small-scaled drills. All obtained values were conveyed into the graphics as well as the tables. Furthermore, photos of all samples under electron microscope were taken and the condition of the photos were examined for surface roughness intensity.

Effect of FeCr Intermetallic on Wear Resistance of Fe-Based Composites

Metal-matrix composites (MMCs) have higher stiffness and mechanical strength than alloys, however they have lower ductility and fracture toughness [1]. In microstructure of MMCs if a bond between particulate reinforcement and matrix has been constituted, then the composite exhibits an ability to withstand high tensile and compressive stresses. Continuous fibers, short or chopped fibers, whiskers and particulates have been used as reinforcement materials in MMCs. Discontinuous reinforcement phase composites are common due to availability, low cost, independence of mechanical properties from particulate orientation [2] and production via a vide range of manufacturing routes [3-6].

Calculation and Comparison of Stress Concentration Factors in CompositeInverted-tooth Chain Link Plates with Various Dimensions

The effect of fiber type and direction on the level of stress concentration factors, k, created by the presence of a notch was investigated for inverted-tooth chain link plates made of unidirectional and symmetric cross-ply laminates loaded on or off axis. The finite element (FE) method was used for this purpose utilizing triangular elements under plane stress conditions. Analysis was performed for three different fiber reinforcements of epoxy matrix: glass, graphite, and boron. Typical mechanical properties reported in the literature for graphite—epoxy, glass—epoxy, and boron—epoxy were used in calculations. The accuracy of the FE code utilized was first checked by calculating the stress concentration factors for an isotropic plate made of steel. The results which were determined by the computer-based FE method were compared with experiment results. It was seen that results agree well with strain-gauge and photo elastic measurements.

Mussel Shell Powder as a Filler Material in Brake Linings

In this study, brake linings made of mussel shell powders as a filler material were investigated in terms of wear behaviour, braking performance, friction coefficient and thermal stability to have an idea about the possibility of implementing mussel shell as a candidate of filler material. Brake linings are composed of relatively soft but wear resistant and high thermal conductive materials with a high dynamic friction coefficient in order to keep stability of the friction force and move the heat away under different braking pressures and travel speeds. The manufacture of semi-organic brake linings requires to identical combination of various type of materials such as metals, ceramics, organic materials, resins and friction modifiers followed by characterization of powders, cold pressing and curing processes to acquire final product. For those purposes, the samples manufactured under optimized 15MPa cold pressing and curing at a temperature of 150°C for 2 hours, undergo braking tests in a specially designed experimental setup enabling to measure variation of temperature and friction coefficient during operation. Weight percentage of the samples was preferred to be 5, 10, 15 and 20% by mass. Mussel shell reveals acceptable braking behaviour as a result of microstructure examinations via Scanning Electron Microscopy (SEM) and evaluations which are; hardness 27.5HB, corrosion resistance 1.63% by mass loss and average friction coefficient of 0.39.

Effects of Temperature and Load on Wear for Different Matrix and Fibre-Reinforced Composite Materials

In this study, wear behaviours of fiber-reinforced and matrix composite materials are experimentally investigated under different speeds, loads and temperature. Composite materials were made of Kevlar-epoxy resin, glass fibre-epoxy resin and glass fibre -polyester resin materials. Tests were conducted for speeds of 0.390 and 0.557 m/s at two different loads of 5N and 10N respectively. Wear in the experiments was determined as lost in mass.In addition, the wear behaviour of samples was investigated through the SEM observation.