Study of the Indentation Process under Specific Technological Parameters

AbstractThere is a large variety of Compressive Forming Processes with different typologies and characteristics. In this paper, the indentation process is studied from the point of view of manufacturing. The influence of technological parameters such as friction and shape factor on the process has been studied. The aluminum alloy AA 6082 has been employed in this study due to its good mechanical properties, light weight and its capacity of being recycled. The Finite Element Method (FEM) has been used for the analysis. The indentation process has been studied under axisymmetric conditions. The forces to carry out the indentation process and the contact pressures have been obtained. Finally, it is shown that the forces and the contact pressures do not have a high dependency on the friction between the surfaces of the punch and the workpiece. The shape factor has a greater influence on the process, especially the width of the workpiece

Study of the Indentation Process under Specific Technological Parameters

AbstractThere is a large variety of Compressive Forming Processes with different typologies and characteristics. In this paper, the indentation process is studied from the point of view of manufacturing. The influence of technological parameters such as friction and shape factor on the process has been studied. The aluminum alloy AA 6082 has been employed in this study due to its good mechanical properties, light weight and its capacity of being recycled. The Finite Element Method (FEM) has been used for the analysis. The indentation process has been studied under axisymmetric conditions. The forces to carry out the indentation process and the contact pressures have been obtained. Finally, it is shown that the forces and the contact pressures do not have a high dependency on the friction between the surfaces of the punch and the workpiece. The shape factor has a greater influence on the process, especially the width of the workpiece

Comparative Analysis of Extrusion Processes by Finite Element Analysis

AbstractExtrusion processes are quite extended in the manufacturing of long products for a wide range of industrial applications. There are different approaches of extrusion processes, depending on either the final shape of the product to obtain or the maximum loading capacity of the equipment to be used. This work presents a comparative study of extrusion processes (solid and cup extrusion), considering both direct and indirect forming conditions and showing the most interesting differences between them. The comparison is realized by Finite Element simulation of the processes, using the code DEFORM F2. The material is a low carbon steel (AISI-1010) and the same extrusion ratio and ram displacement are considered in all cases. By comparing the required forces it can be concluded that required loads are higher in cup extrusion processes than in solid extrusion ones. Regarding the friction load, the maximum contribution due to the die-billet contact in cup extrusion is much higher than in the case of solid extrusion. On the contrary, the maximum friction load contribution due to the container wall is much higher in the case of solid extrusion than in cup extrusion

Azzawi Dates (Phoenix dactylifera) as a Substitute for Corn as an Energy Source in Sheep Diet: In vitro Gas Production and Fermentation

In vitro gas production technique was used in the current study to evaluate Azzawi date (AD) as a substitute for corn grain (CG). The AD was used to replace corn grain at graded levels in the proportion: 0:100 (CG), 25:75 (AD25), 50:50 (AD50), 75:25 (AD75), and 100:0 (AD100). Gas production (GP) was continuously measured by incubating samples in buffered rumen fluid from cannulated sheep and it was recorded at 3, 6, 9, 12, 24, 48 and 72h of incubation. Cumulative GP, kinetics of GP (a, b and c), ammonia nitrogen (NH3-N) and volatile fatty acids (VFA) concentrations were determined, while metabolizable energy (ME), net energy (NE), organic matter digestibility (OMD), microbial protein (MP) were estimated. The gas volume was increased (P<0.05) at 12h with increasing the substitution levels of AD in the feed, the values ranged between 31.3 and 44.7 ml/200 mg DM. However, it was found to be decreased (P<0.05) at 48 and 72h with increasing substitution levels of AD. There were no differences in the gas production found at 24h. Data of VFA, NE, OMD and MP were similar (P>0.05) among the feeds. The energy (ME; MJ/kg DM) value of AD25 (10.4) and AD50 (10.3) were comparable to that of CG (10.5); however it was reduced (P<0.05) with AD75 and AD100. Data demonstrated that, Azzawi date at the level of 50 g/100g of substrate (i.e., AD50) may have similar energy contents as of corn grain, and it can be used as a source of energy in ruminant diets either alone or in combination with corn grain

Uncorrelated scattering approximation revisited

The formalism to describe the scattering of a weakly bound projectile nucleus by a heavy target is investigated, using the Uncorrelated Scattering Approximation. The main assumption involved is to neglect the correlation between the fragments of the projectile in the region where the interaction with the target is important. It is shown that the angular momentum of each fragment with respect to the target is conserved. Moreover, when suitable approximations are assumed, the kinetic energy of each fragment is also shown to be conserved. The S-matrix for the scattering of the composite system can be written as a combination of terms, each one being proportional to the product of the S-matrices of the fragments.Comment: 27 pages, 6 figures, submitted to Nucl. Phys. A (v2: minor misprints and grammatical errors corrected

Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV

Quasi-elastic scattering of 6He at E_lab=27 MeV from 197Au has been measured in the angular range of 6-72 degrees in the laboratory system employing LEDA and LAMP detection systems. These data, along with previously analysed data of 6He + 208Pb at the same energy, are analyzed using Optical Model calculations. The role of Coulomb dipole polarizability has been investigated. Large imaginary diffuseness parameters are required to fit the data. This result is an evidence for long range absorption mechanisms in 6He induced reactions.Comment: 10 pages, 10 figures, minor corrections. To appear in Nucl. Phys.

Breakup mechanisms in the He 6 + Zn 64 reaction at near-barrier energies

New experimental results for the elastic scattering of He6 on Zn64 at incident energies of 15.0 and 18.0 MeV and He4 at 17.5 MeV along with results already published at 10.0 and 13.6 MeV, are presented. Elastic and α experimental cross sections are compared with coupled-reaction-channel, continuum-discretized coupled-channel, and DWBA inclusive-breakup models. The large yield of α particles observed at all measured energies can be explained by considering a nonelastic breakup mechanism.Spanish Ministerio de Economía y Competitividad and FEDER funds (FIS2014-53448-C2-1-P, FIS2017-88410P, FPA2016-77689-C2-1-R)European Union’s Horizon 2020 65400

Tamaño de muestra para el desmote experimental y propiedades de la fibra en el algodonero (Gossypium hirsutum L.).

El presente estudio se realizó durante los años 1988 y 1989 en el Centro de Investigación Motilonia, ubicado en el municipio de Codazzi (Cesar, Colombia). El objetivo fue determinar el tamaño óptimo de muestra que permita una mejor estimación de los parámetros del desmote experimental y las propiedades de la fibra en el algodonero. Para ello se evaluaron 6 variables de interés en 5 variedades de algodón a través de tamaños muestrales de 25, 50, 75 y 100 motas por parcela, utilizando para tal fin el coeficiente de variación. Los resultados señalaron diferencias significativas entre los tamaños de muestra para el porcentaje de fibra, longitud y finura de la misma, igualmente interacción años x tamaño para la longitud, y variedad x tamaño, para el porcentaje, resistencia y finura de la fibra; en tanto que la interacción triple (año x variedad x tamaño) no fue significativa para ninguna de las variables estudiadas. Los coeficientes de variación señalaron que el mejor tamaño de muestra fue el de 50 motas por parcelaInstituto Colombiano Agropecuario - ICAAlgodón-Gossypium herbaceu

Reversible collapse of insoluble monolayers

II Encuentro sobre nanociencia y nanotecnología de investigadores y tecnólogos de la Universidad de Córdoba. NANOUC

Colapso reversible de monocapas insolubles. Influencia de la línea de tensión de los dominios

II Encuentro sobre nanociencia y nanotecnología de investigadores y tecnólogos de la Universidad de Córdoba. NANOUC