Papers by Keyword: Orientation

Abstract: The effect of the characteristics of austenite interface with ferrite on the pearlite transformation behaviour after intercritical annealing was investigated. Most austenite grains were situated mainly on ferrite grain boundaries and had the Kurdjumv-Sachs (K-S) or near K-S relationship to one of the neighbor ferrite grains before pearlite transformation. The pearlite transformation started mainly from the austenite grain boundary faced to ferrite. The pearlite transformation showed stasis. This indicates that some austenite is stabilized thermally against the pearlite transformation. The fraction of austenite having only the K-S or near K-S interface to neighbor ferrite grains was correspond to the fraction of austenite grains which does not include pearlite. The pearlite transformation was difficult to start from austenite interface having the K-S relationship to ferrite since the interface between austenite grains and ferrite grains was stabilized energetically in the case of their interface having the K-S relationship.

Abstract: In this study, we propose a simple and effective approach to enhance (110) orientation in diamond films grown on (100) Si substrates by microwave plasma chemical vapor deposition. It is found that the crystalline structure of diamond films strongly rely on the CH₄ concentration in the nucleation stage. Under the same growth condition, when the CH₄ concentration is less than 7% (7%) in the nucleation stage, the diamond films exhibit randomly oriented structure; once the value exceeds 7%, the deposited films are strongly (110) oriented. It could be verified by experiments that the formation of (110) orientation in diamond films are related to the high nucleation density and high fraction of diamond-like carbon existing in nucleation samples.

Abstract: Orientation of fibre preforms is an important factor that affects the properties of short natural plant fibre composites. In this paper, oriented short hemp fibre mats were produced using dynamic sheet forming and the fibre orientation distribution in the mats was analysed using ImageJ software as well as by a simple program developed on a MATLAB software package. The OrientationJ plug-in of ImageJ gave an orientation distribution curve with a peak at a predominant direction of 0° supporting alignment during dynamic sheet forming and from MATLAB software, a mean ratio of 0.64 was obtained for the oriented mats compared to 0.74 for an aligned bundles.

Abstract: Polymer matrix composites are widely applied for the manufacturing of components employed in hostile environments to increase the service life and sometimes at a later stage for the reclamation of worn out parts. Every decade, numerous materials and techniques are being introduced and developed for the effective protection of low cost bulk materials out of which the fabrication of components could be done. Among such techniques hand layup, matched die mould methods, contact mould methods, filament winding and pultrusion methods has being employed increasingly in the process industries which has several significant advantages over other processes. It has become a process of its reliability, better process control, ease of use, good surface finish and closeness of dimensions. One among the method matched die mould method was selected as the process of preparation of the composite plate in the presented work. However, there are some inherent problems with control of resin flow, application of high temperature for curing during fabrication process. To address those main problems, a systematic investigation was carried out. The selected material is natural plant fibre available in abundant called “Crotalaria juncea” and is being employed as a green manuring plant in agriculture. In the investigation, the fibre is taken in two different forms of random and woven orientations and plate fabrication is done with unsaturated polyester resin as the matrix. The investigation is on woven orientation of biaxial, biaxially stitched and unidirectional woven types were done using the fibre to the size of the plate to be fabricated. Woven fibres of these three types were done at fibre design centre, Kerala. It was found that the fabrication could be done by placing two layer and three layer of the woven mat alone. So for the three woven types, two layer and three layer plates were fabricated to give about six plates in total. Here again to arrive at a closeness value for each combination, three plates were fabricated and the average value is got by testing. Tensile, flexural, impact and shear testing was done on all the plates as per ASTM standards and the responses were noted and plots were drawn and studied for the orientation for which the material possessed best property. The second part of the study was, with the experimental results got from the woven orientation, analysis was done by ANSYS and LS-DYNA software for the mechanical property and the responses got, was matching with the experimental testing methods and found that both the results were nearly the same thereby optimizing the results achieved. This is presented in detail in the forth coming chapters. The studies revealed that the fibre parameters taken had a significant influence on the mechanical properties. It was found that at a particular weight fraction the mechanical properties achieved the highest values in case of random orientation and particular woven orientations in case woven types. The increase in layers also had an influence over the property of the material. This composite prepared also initiates us in preparing newer composites with existing natural fibers, which haven’t been yet explored and which can reduce the cost. This gives way also in preparation of the same and releasing a newer variety of material to the Engineering industry which can be suited for some required application.

Abstract: The F-3 fiber is a trade name of a recently developed type of heterocyclic para-aramid fibers in China. To investigate the relationship between structure and compressive properties for F-3 fiber, the structural parameters and compressive strength have been analyzed in detail compared with the Kevlar-49 fiber. The structural parameters were determined by wide-angle X-ray diffraction (WAXD) analysis and sonic velocity method. The results showed that the orientation of chains of F-3 fiber was higher than that of Kevlar-49 fiber. The results of the tensile recoil method showed that F-3 and Kevlar-49 fibers had approximate compressive strength. The analysis of relation between structure and mechanical properties suggested that the combination of orientation parameter and shear modulus between adjacent chains resulted in the approximate compressive strength of F-3 and Kevlar-49 fibers.

Abstract: The electromagnetic parameters of magnetic unoriented and oriented Ce₂Fe₁₇N_3-δ powders/Silicone composite with 15 vol% were investigated in the 0.1–18 GHz range. It was found that the initial permeability increased from 2.78 to 3.6 as well as the optimal RL reached –61.3 dB with a thickness of 1.91 mm at 9.01 GHz for the composite after orientation. The microwave absorbing properties of oriented composite were greatly enhanced resulting from the perfect impedance match condition improved by rotational magnetic orientation. This novel rotational magnetic orientation method might provide a new way to design high performance microwave absorbers.

Abstract: Heat infiltration through the external wall of refrigerated vehicles has been a concern to food industries considering high thermal load required to sustain unbroken cold chain. In this research, experiments were carried out with known fibres contents laid out at various orientations and the effect on the heat transfer measured. The results indicate that the estimated overall heat transfer coefficient of the composite reinforced with 10%wt. of fibre at 0^o orientation (G₁₀E) offers the lowest U value of 0.386950 W/m²K and 0.196680 W/m²K for 50 mm and 100 mm insulation thicknesses respectively. The effect of fiber orientation in the composite panel in energy saving was to a large extent minimal when compared to the un-oriented composite panel

Abstract: The development of bio-composites as biodegradable and renewable materials for sustainable technology are advantageous in creating a green and healthy environment. However, the application of natural fiber as a bio-composite material have been found to be restricted especially as it has lower thermal resistance in comparison to synthetic fiber. Therefore, the objective of this study is to investigate the influence of fiber orientations on the tensile properties at various tensile temperatures for unidirectional kenaf polypropylene (PP) composite. Samples were prepared by hot pressing process. In this study, kenaf long fibers that are produced from water retting process is use as a reinforcement agent while PP as a polymer in the composite fabrication. A tensile test was carried out at different temperatures (30°C, 60°C, 90°C, 120°C) for various orientations (0°, 45° and 90°). It was found that an increase of temperature will reduce the modulus and tensile strength where the highest reduction occurred between 60°C to 120°C and most significantly on the orientation of 45° and 90°, which is lower than pure PP. This concludes that the application of kenaf PP composite is optimum between room temperature with a cut-off temperature at 60°C.

Abstract: Additive manufacturing processes offer the ability to manufacture highly complex geometries, but are limited in terms of the achievable surface quality. These limitations are based on physical restrictions, especially the need of support and the powder-bed environment, and economic decisions. In this study, the development of the morphology of surfaces with varying inclination angles was investigated on the example of 316L stainless steel. Surfaces with low inclination angles to the manufacturing plane suffered extensively from the process related staircase effect, whereas perpendicular side faces revealed high dependencies on the interaction with the powder-bed.

Abstract: In recent years, in order to achieve weight reduction and crashworthiness, automotive part was manufactured using patchwork blanks. The smaller patches were welded on a main sheet to achieve a local reinforcement, which is called the patchwork. In this study, the effect of the spot-weld line orientation on the formability of patchwork blanks for high-strength low alloy (HSLA) steel was investigated in uni-axial tension mode by limiting dome height (LDH) test. A FE-analysis and experiment was performed to gain a better understanding of the formability for limiting dome height and strain distribution. As a result of the LDH test and FE-analysis, differences in the dome heights and forming limits were observed patchwork blanks with spot-weld line orientation of 0°, 45°, and 90°, respectively. For the 0° and 45° patchwork blanks, the dome heights was lower than those of 90° patchwork blanks because of the stress concentration in the pole side.