Papers by Keyword: Aspect Ratio

Abstract: The two aspect ratios 1.0 and 0.5 analysed comparatively to perform a stability study of a 120° partial arc journal bearing have lubricated with a fluid of couple stresses. Reynold’s equation in modified form is obtained for couple stresses and coupled with elasticity equation to predict the impact of deformation in bearing liner on stability characteristics of journal bearing to know its performance. The results quoted here are in terms of attitude angle, somerfeld number, critical mass, whirl frequency and threshold speed. The conclusion made shows that the bearings with high aspect ratio (1.0) are more stable than aspect ratio 0.5 for the fluid of couple stresses and its stability is improved by the use of fluid with couple stresses. Threshold speed is reduced with an increase in the factor of liner deformation and shows that the region of stability is reduced on increasing deformation of bearing liner.

Abstract: A study of the heat transport and fluid flow behaviour around a tilted elliptical cylinder that is located concentrically in a square enclosure whose top horizontal wall is driven by a lid in the positive x-direction is presented. Due to the disparities in the results of convective heat transfer in square cavities in the literature, this study seeks to investigate the combined effects of the Grashof number, Aspect ratio of the geometry, and Elliptical cylinder inclination angle on the dynamics of thermal and flow fields within the geometry investigated. COMSOL Multiphysics 5.5 version was used to resolve the non-dimensional transport equations, while simulations were performed to examine the implications of salient parameters such as the elliptical inclination angle , Grashof number and aspect ratio . The simulation outcomes are displayed as average Nusselt numbers, velocity streamlines, and isothermal contours. Findings from this study show that an increase in aspect ratio resulted in increased heat transfer at the elliptical cylinder wall, with the highest rate of heat transfer occurring when .0. Furthermore, the inclination angle increments when Gr= and led to a reduction in the average Nusselt number of the elliptical cylinder wall. At and AR ranges of , the value of the elliptical cylinder wall increased as the ellipse's inclination angle increased. The findings of this study have found use in heat transfer systems, particularly electronic cooling and nuclear technologies.

Abstract: Aspect ratio of crack is one of key factors of fatigue strength prediction in engineering design and civil structures using fracture mechanics and nondestructive inspection. However the author proposed the method to predict crack shape, it has the error caused by stress distribution of notch. In this study, in order to investigate the relationship between predicted crack shape and empirical observed it, the aspect ratio of cracks at notch root was observed, analyzed and discussed. We obtained the two important conclusions which are between predicted crack shape and empirical observed it. Predicted aspect ratio of crack was 17% bigger than that of observation result. The aspect ratio of crack should be defined considering scale of crack and notch shape.

Abstract: Aspect ratio of crack is one of key factors of fatigue strength prediction in engineering design and civil structures using fracture mechanics. Their empirical shapes are changed by stress concentration. However, it was not clear how stress concentration affects empirical results including crack shape and size. In this study, in order to investigate the relationship between stress concentration and crack geometry, the aspect ratio of cracks at notch root was observed and discussed. We succeeded to capture two important relationships which are between stress concentration and crack shape, and between crack initiation point at notch root and crack shape, respectively.

Abstract: Cutting fluid plays an important role in machining processes to achieve dimensional accuracy, reduce tool wear, and improve tool life. Use of flood cooling conventionally used in machining is not cost effective and consumption of huge amount of cutting fluids is not health and environmental friendly. Therefore, one of the alternatives is to use minimum quantity of lubrication (MQL) in machining process. MQL is eco-friendly and has economical advantage on manufacturing cost. Study of the effects of MQL on burrs and aspect ratio should be carried out because burrs and aspect ratio are important issues in microdrilled parts used as microfluidic channels in bio-medical applications. In case of micromachining, flood cooling is not recommended to avoid any possible damage of the microstructures. As a result alternative solutions are sought. This paper investigates and compares burrs and aspect ratio in dry microdrilling and microdrilling with the presence of MQL on aluminium alloy 1100. The relationship among tool diameter, feed rate, and spindle speed on the area affected by burrs and drilled hole aspect ratio are analysed. The values of aspect ratio for both conditions show that there is slight improvement on aspect ratio in MQL over dry drilling. MQL has significant influence on affected area by burrs. It is observed that low spindle speed, high feed rate, and bigger drill diameter should be used along with MQL to reduce burrs.

Abstract: The formation of a caldera poses a serious risk for the society and the environment. There are several established processes (mostly dealing with the conditions inside the reservoir), which must take place in order to reach a collapse leading to the caldera. The role of magma chamber geometry is investigated in this paper, exploiting the numerical modeling. The results indicates that the knowledge of the magmatic system dimensions can provide a helpful factor for an assessment of the caldera formation scenario.

Abstract: The objective of the present study is to investigate the engineering properties of paddy (One-thousand-one) grown in the coastal region of Odisha (India). The average length, width and thickness of paddy are measured as 8.80 mm, 2.65 mm and 1.91 mm respectively at moisture content of 28% (wb). The mean bulk density and true density of the particular variety of paddy are measured to be 0.61 g/cc and 1.47 g/cc. Properties like equivalent diameter, sphericity, grain volume, grain surface area, aspect ratio and porosity are calculated to be 3.58 mm, 0.40, 24.00 mm³, 35.66 mm², 0.30, 58.24% respectively. The angle of repose and angle of friction of the paddy grains are determined to be 37.73o and 0.43o, 0.25o, 0.30o with plywood, glass and galvanized iron respectively. These engineering properties are useful in design of forced convection dryer for the drying and processing of paddy.

Abstract: In the present numerical investigation, the flow field of confined slot air jet in a rectangular computational domain is reported. In the present work the flow field parameters like reattachment length, vortex center and horizontal velocity profiles for various Reynolds numbers and for various aspect ratios are presented .The present study reveals that the vortex centers are moving in a downstream direction with increase in Reynolds number. The reattachment length is directly dependent on the Reynolds numbers. In case of vortex dynamics, the vortex size is indirectly dependent on the inlet jet width. In the present investigation, SIMPLE algorithm is used to solve the governing equations. It is concluded that the aspect ratio and the Reynolds number are playing dominant roles in flow field of the present computational domain.

Abstract: Homoepitaxial layers with different growth pit density were grown on 4H-SiC Si-face substrates by changing C/Si ratio, and the influence of the growth pit density on Schottky barrier diodes and metal-oxide-semiconductor capacitors were investigated. Even though there were many growth pits on the epi-layer, growth pit density did not affect the leakage current of Schottky barrier diodes and lifetime of constant current time dependent dielectric breakdown. By analyzing the growth pit shape, the aspect ratio of the growth pit was considered to be the key factor to the leakage current of the Schottky barrier diodes and the lifetime of metal-oxide-semiconductor capacitors.

Abstract: It is well known that nanocrystalline materials have enhanced diffusion properties due to their high grain boundary density which act as fast diffusion channels compared to the lattice. In this paper, we aim at simulating the nitriding process of a pure iron nanostructured by NanoPeening® process. We use a simple diffusional approach taking into account the grain size and the grain morphology resulting from the NanoPeening® treatment. EBSD measurements are carried out to extract morphological parameters which are used in the homogenization method to extract the effective diffusivity distribution. Then a 1D diffusion simulation is performed with this distribution and shows that the grain morphology resulting from the NanoPeening® treatment does not deteriorate the diffusion properties of the material but in fact, improves the nitrogen penetration depth and the diffusion kinetics in addition to the effect of the grain size reduction.