Papers by Keyword: Core

Abstract: Fiberglass reinforced plastic fishing boats is a new type of energy saving and emission reduction boats, which is a significant revolution of fishing craft. However, the design of FRP fishing vessels in China continue to use the similar method employed by steel fishing vessels, which ignores the designability of fiberglass, leading to the light and high strength characteristic of glass fiber buried. the typical structure of FRP boats were analyzed, including the study on the influence of core material on the mechanical properties of cap type girder and the feasibility by using the equal sectional dimension in the Patran software of beam element to equivalent simulate the cap-type material, which simplified the whole ship building process of the finite element model and improved the computational efficiency in this pape.

Abstract: An era of a high-gravity oil of the Samotlor field formations AV_2-5 and BV_8-10 is near to its end. The production deposits of the AV₁^1-2 horizon are the main reserve of oil production and the basic prospect in this area. Stratigraphically, the AV₁^1-2 horizon belongs to the Alym suite of the early Aptian Age that was distinguished as an individual unit at the 1967 interdepartmental stratigraphic meeting with the stratotype in the Uvat test well. This part of the section started to form around 400,000 years ago and is represented by siltites with interlays of clays and sandstones, primarily bioturbated ones, which causes the specific lens-clustered laminarity of these rocks (Ryabchik) with rare double leafs and single pancake-shaped primitive foraminifers such as saccamina. Specific features of the geological structure and oil-and-gas content of the AV₁^1-2 horizon within the area under consideration were in various aspects described earlier in the works of many researchers [1-8]. Nevertheless, when new geological and geophysical information had been accumulated, the need arose to cover this issue once again. Since it makes us consider the geological modeling of formations in the horizon from quite a different angle, we need to create various structural models of HC reservoirs, development flow diagrams, etc. The research objective is to define the genesis of producing deposits of the AV₁^1-2 horizon and identify fascia complexes in them. Using a system of special studies and methods for analyzing geological development and structure (paleotectonic, grain size, fascia, electrometric, etc.), the areas of sedimentation and fascia systems were diagnosed within the area under research.

Abstract: The development of high performance materials made from natural resources is increasing worldwide. The interest in natural fiber reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. The coconut fiber can be a potential candidate to replace the industrial core and foam which its application are worldwide and it is used to increase the thickness of the fiberglass boat. In this research, three types of testing panel are constructed by using 10 mm of Coconut Fiber, 3D Core Foam and Infusion Grooved PVC Foam as the sandwich core. The resin infusion method which is produce quality final products have been used. The findings be obtained by conducting two testing methods, for the Flatwise Tensile Strength testing, the specimens taken from Coconut Fiber product yielded a higher value of strength which is 3.005 MPa compared to the specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 2.963 MPa and 1.264 MPa respectively. For the Flatwise Compressive Strength testing, the specimens taken from the Coconut Fiber product had higher value of compressive stress compared to the value of specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 29.66 MPa, 2.58 MPa and 4.68 MPa respectively. This research has proved that the Coconut Fiber is quite suitable to become as one of the laminating schedule for the construction of the fiberglass boat hull.

Abstract: The article is focused on monitoring the cooling effect of the liquid CO₂. This unconventional cooling system was used as a supplement method added to the standard tempering system of the die casting mould particularly intended for aluminium alloy castings. Standard tempering system of die casting moulds enables preheating the mould to operating temperature before the particular production starts and then the tempering system regulates the temperature balance between the mould and the casting during individu al production cycles. Conventional cooling system is based on drilled or milled interconnected channels with predominantly parallel orientation to the parting line, through which a tempering medium (oil, water etc.) flows. This system has some limitations that can be overcame with utilizing of special approaches. One of these approach is employment of liquid CO₂.This study revealed the positive impact of this additive cooling on homogeneity of temperature field distribution on the mould cavity surface, which assures first of all the uniform coating the cavity surface by separating agent and sticking the melt on the cores. The products were analysed using the metallographic and CT analyses and the leak tightness was tested.

Abstract: The corrosion behavior/rate of TMT steel bars in different corroding media such as rain water, storage atmosphere and concrete ponded in 10% sodium chloride solution has been investigated for a corrosion duration of 40 weeks. The corrosion rate of TMT steel bars corroded in the three media was measured at an interval of 4 weeks. Both macroscopy and microscopy were carried out to reveal different zones such as hardened case, soft core and transition zone in the cross-section and microstructure in these zones respectively of the TMT steel bars in the as received condition and after corrosion of 40 weeks duration. It was found that the corrosion rate of the TMT steel bars in rain water decreases gradually with corrosion duration and reaches a minimum value at 24 weeks of duration after which the corrosion rate increases. The corrosion rate of TMT steel bars in storage atmosphere initially increases and after reaching a maximum value at 16 weeks duration it starts decreasing. The corrosion rate of the TMT steel bars in concrete with 10% NaCl solution decreases very slowly and after reaching minimum value at 32 weeks of duration it starts increasing gradually. It was also found that the corrosion rate of the TMT steel bar in rain water is much higher than that of the TMT bar in storage atmosphere and the corrosion rate of the steel bars in concrete with NaCl solution is the lowest of all the media.

Abstract: The effects of angle of convergence on the shape and thickness of the core are analyzed theoretically by considering variable film thickness in an externally pressurized circular thrust bearing. Using the assumptions of the lubrication theory, modified Reynold’s equation and the governing equations are obtained. Using the boundary conditions of the problem in the constitutive equations we get the velocity of the core region as well as flow region. By considering the equilibrium of an element in the yield surface, an algebraic equation to determine the thickness of the yield surface is derived. Numerical solutions are obtained for the thickness of yield surface and velocities for various values of Bingham Numbers and the angle of convergence.

Abstract: Nanoweb fabricated by electrospinning has a large specific area and a small pore size which can be controlled through a spinning process to enable a strong adsorption and selective permeability. It is required to produce nanofiber of different polymer mixture with a limited miscibility for improvement of physical, chemical, or biological properties. In this study, poly (vinyl alcohol) (PVA)/polyurethane (PU) nanofibers were produced by coaxial electrospinning. PVA (core)/PU (shell) nanofibers were defect-free and had a uniform thickness. The pseudo core/shell structure of PVA/PU nanofibers was confirmed by transmission electron microscopy. The presence of PVA and PU in the nanofibers was identified by ¹³C solid state nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, and X-ray diffraction analysis. Water contact angle was reduced by incorporation of PVA in a core of PU nanofiber. For variety of biomedical applications, bioactive substances such as antibiotics and proteins can be incorporated in a core of hydrophobic PU nanofiber by coaxial electrospinning of water-soluble polymer/bioactive substance mixture.

Abstract: High-temperature tensile deformation was performed using an oxide-dispersionstrengthened (ODS) ferritic steel,, which has grain structure largely elongated and aligned in one direction, in the perpendicular direction. In the superplastic region II, two-dimensional grain boundary sliding (GBS) was achieved, in which the material did not shrink in the grain-axis direction and grain-boundary steps appeared only in the surface perpendicular to the grain axis. In this condition, a classical grain switching event was observed. Using kernel average misorientation maps drawn with SEM/EBSD, dominant deformation mechanisms and accommodation processes for GBS were examined in the different regions. Cooperative grain boundary sliding, in which only some of grain boundaries slide, was also observed.

Abstract: To ensure optimal temperature conditions during casting cycle the pressure casting moulds are equipped with cooling systems. These days the cooling systems used in the most of Czech foundry plants enable pre-heating of pressure casting moulds to the working temperature before start-up of production and during casting operation to keep optimal temperature balance among the casting and the mould. Pressure casting mould temperature balance is provided by system of mutually connected channels which are mostly parallel with parting line and inside those the heat transfer medium flows. However such a system allows removal only limited heat amount from the most overheated places of the casting mould and does not allow heat removal from cores of small diameters. This inhomogeneous heat removal causes porosity of the casting in certain areas and also lifetime of the pressure casting mould is dramatically reduced. Cooling by means of liquid CO₂ was developed as one of the new cooling possibilities for such places in the pressure casting mould where the heat is concentrated and for standard cooling systems it is too complicated to fully control the heat processes there. The paper deals with the behaviour monitoring of the new cooling system utilizing the potential of liquid CO₂. This system was applied into pressure casting mould core and its final impact on the casting quality in the close surrounding was observed.

Abstract: In this paper, an easy casting method of an ingot with through holes is shown. The Core-Bar-Pulling Method is proposed to improve the disadvantages of lotus type porous metal. The through holes were formed by pulling core-bars from a semisolid ingot. Holes with diameters ranging from 0.5 mm to 5 mm and length 50 mm were made in Al-Si alloy ingots. The relationship between temperature and formability of the holes was investigated by using eutectic Al-Si alloys. The pulling of core-bars and the forming of holes were easy, under the condition that the Si content was less than 6 mass%. This means that the forming of holes in Al-Si alloys is easy under the condition that flow ability at semisolid condition decreases.