Papers by Keyword: Tensile Strength

Abstract: Many of the excavated pottery artifacts are suffering from different deterioration aspects. The pressure of burial environment is considered the most deteriorative agent for pottery in soil, which leads to damage of the artifact. Therefore, it is necessary to join these damaged parts to be suitable for museum display. The adhesive materials play a significant role in the joining processes of these artifacts. In this study, Paraloid B-72 in its traditional and nano form was prepared (50% in acetone) as adhesive for pottery artifacts. Twelve pottery tiles (14 ×4×1 cm) were prepared and then were adhered together with the adhesive in traditional and nano forms. The pottery samples were exposed to artificial aging as follows; accelerated heat-humid aging (temperature 100°C and 60% relative humidity) and light aging by U.V lamp for 100 hours. Visual assessment and several analytical techniques were used for the evaluation of the selected adhesive. The analytical techniques are transmission electron microscope (TEM), scanning electron microscope (SEM), color change and tensile strength. The results obtained from transmission electron microscope showed that grain size of nano paraloid was ranging from 33 to 51 nm where the particle size of the traditional paraloid was in the range between 103 to 150 nm. Visual assessment proved that nano paraloid had some simple changes in appearance. Scanning electron microscope revealed that the nano paraloid was more resistance for aging than traditional form. Color change revealed that nano paraloid gave the lowest level of total color differences (ΔE) after light, heat-humid and light-heat aging with 2.31, 3.26 and 4.60 respectively. The tensile strength revealed that nano paraloid gave highest tensile strength (81.3 N/mm²). According to these results, we recommend the use of nano paraloid in joining of archaeological pottery artifacts.

Abstract: Produced Profiles by direct recycling of aluminum chips in hot extrusion process were achieved by temperature related parameters using preheating temperature 450 °C, 500 °C, and 550 °C for duration 1 hour, 2 hours, and 3 hours preheating time. By using Design of Experiments (DOE) procedure with full factorial design and three center points analysis, the results showed that the preheating temperature factor is more important to be controlled rather than the preheating duration and increase of temperature conducted to the high tensile strength. The profiles extruded at 550 °C and 3 hours’ duration had obtained the optimum condition to get the maximum tensile strength. The influence of parameters of hot extrusion process on fracture surfaces of the recycled samples was also investigated and discussed.

Abstract: A study of the mechanical properties of the finished metal products was carried out. All types of metal products are subjected to continuous quality control, both on the production output at the manufacturer of billets, and on the production entrance at the consumer of metal. Control subject are: strength characteristics (tensile strength σ_в and yield stress σ₀₂ and the characteristics of plasticity (relative elongation δ and relative necking ψ). The pipe steels have another important controlled characteristic: the impact toughness КСU-60. All the test methods are the destroying ones and are characterized by high complexity. The task of reducing the types of tests, the introduction of a comprehensive indicator of product quality is an urgent technical task. The purpose of this work is to study the regularities of changes in the indicators that determine the quality of the sheet metal from the pipe steel.

Abstract: Nanofibers have high cell affinity due to their fine structure and surface roughness, and are expected to be used as biomaterials. In particular, magnetic nanofibers containing magnetic particles are expected to be used for magnetically induced drug delivery systems and hyperthermia. However, due to the aggregation of the magnetic particles contained in the nanofibers, there is a problem that the aggregation location becomes a starting point of fracture and causes a decrease in tensile strength. In this study, to improve the dispersibility of magnetic particles in Magnetite/PLA nanofiber nonwoven fabrics for suppressing the decrease in tensile strength, magnetite is subjected to surface treatment with oleic acid or stearic acid and ultrasonic agitation. Magnetite/PLA nanofiber nonwoven fabric was prepared by the electrospinning method, and dispersion of magnetite in PLA nanofiber nonwoven fabric and tensile strength were evaluated. Magnetite dispersion was improved by the surface treatment and increasing the ultrasonic agitation time. In particular, by performing the stearic acid treatment and prolonging the ultrasonic agitation time, the magnetite dispersion tended to be improved. This treated Magnetite/PLA nanofiber nonwoven fabric showed higher tensile strength.

Abstract: Carbon nanotube (CNT) is excellent in mechanical and thermal characteristics, and are expected to be used in various fields such as nanoelectronic devices and reinforcing nanofillers for composites. It is expected that mechanical properties can be improved by adding CNT into the polymer. However, since CNT exists in a state of aggregation due to van der Waals forces, it is necessary to uniformly disperse CNT in order to fully extract the properties of CNT. In this study, CNT/polyamide 6 (PA6) composite nanofibres were fabricated by the electrospinning method. In order to disperse CNT in the CNT/PA6 nanofibres, CNT were subjected to air oxidation treatment. As a result of evaluating the dispersibility of CNT by sedimentation test, the dispersibility in pure water and HFIP is improved by oxidizing the surface of CNT. By conducting tensile tests and SEM observation of the nanofibre non-woven fabric, the influence of the surface treatment on the tensile strength of CNT/PA6 nanofibres and the dispersion of CNT was clarified. Although the addition of untreated CNT to PA6 nanofibres reduces the displacement at break, air oxidized CNT/PA6 suppressed the formation of CNT aggregates, and showed higher tensile strength and larger displacement at break than untreated CNT/PA6.

Abstract: The RPP introduction has been established up to 3% by weight of the dry concrete mix is ​​accompanied by a decrease in the fine-grained concrete tensile strength in compression to 40% and in tension during bending to 15%. The relationship between the tensile strength limit in bending and compression for the studied materials is invariant to the cement and RPP type. With the concrete tensile strength in tensile bending increase, there is a weak tendency to a decrease in the adhesion ratio value to the concrete base and tensile strength. The adhesion amount to the concrete base with RPP increasing dosage can either increase or decrease after a certain limit, depending on the cement properties. The maximum increase in adhesion to the concrete base was 37%, while the decrease in the concrete elasticity initial modulus was 26%.

Abstract: The use of secondary materials resulting from recycling is currently receiving increased attention, since their use reduces the anthropogenic burden on the environment. In this regard, composite materials based on recycled polypropylene (PP) and short-chopped basalt fibers (BF) are prepared. To improve the adhesion of BF to the polymer matrix, their surface was treated with CCl₄ vapors in a flow reactor in order to replace the oxygen atoms with chlorine atoms. Then, the chlorinated surface was treated in a CH₄ stream to replace chlorine with hydrocarbon groups. Composites contained from 5 to 20% BF; each composite was heated at temperatures of 500, 650 and 750°C. Stress-strain curves at tension and compression were obtained for all samples. The modulus of elasticity at tension increased to 2120 MPa with a BF content of 20%, and for the initial secondary PP this modulus is equal to 705 MPa. The strength increased to 42 MPa (for the initial secondary PP, the strength is equal to 32.0 MPa). The specific impact strength increased to 18.3 kJ/m² (for the initial secondary PP this value is 14.4 kJ/m²). The chemical structure of hydrocarbon groups most compatible with PP was determined by calculation using the Cascade computer program (INEOS RAS). IR studies and microanalysis showed the presence of such groups on the surface of the BF, which are chemically bound to silicon atoms.

Abstract: The paper considers the possibility of improving the quality of gray cast iron castings by controlling the cooling rate of castings in a mold. It is shown that the use of differentiated cooling can increase tensile strength of cast iron by 12-16%

Abstract: In this paper, the mechanical properties of Polyethylene terephthalate-glycol (PETG) tensile test specimens have been investigated. The test pieces were prepared using fused deposition modelling (FDM) 3D printing technology. Three print settings were examined which are: raster direction angles, print orientations, and infill percentage and patterns in order to evaluate the anisotropy of objects when employing FDM print method. The variations in stress-strain curves, tensile strength values and elongation at break among the tested samples were studied and compared. Illustration for the broken specimens after the tensile test was accomplished to know how the test pieces printed with various parameters were fractured. A comparison with some previous results regarding the elongation at break has been carried out.

Abstract: In the construction industry there is no method for tensile testing of materials of basalt complex filaments of small diameters and roving. The existing methods of testing fibers and roving presented in regulatory documents are intended for textile materials and materials based on fiberglass. The studies cited in the article were aimed at studying the strength properties of roving materials and a multifilament yarn based on basalt fibers, as well as working out methods for testing them. The article presents studies of the strength characteristics of roving and complex yarn based on basalt fiber, on which testing of basalt material samples was tested. The strength characteristics of various forms of basalt materials for various adhesive processing were obtained. The applied experimental test procedure was appreciated positively.