This didactic instructional article presents an original educational approach, directed toward the improvement of existing university curriculum using effective and student-friendly teaching of ...fundamentals of modern scientific research for graduate and undergraduate students, emphasizing scientometrics and integrity. This approach applies to students majoring in a wide range of basic and applied academic specializations in the various branches of science, engineering, computation and technology. The present methodological paper provides a novel, humanized and student-centered way of presenting a comprehensive and unified didactic explanation of originally narrated instructional material, which is based on the adaptation, generalization and creative re-thinking of the previous ten years of the author’s publishing experience. This experience has been in Scopus®- and SCIE WoS® Core Collection-indexed referred academic periodicals. The proposed learning material has found a full-scale educational approbation for a widely-targeted audience of full-time young bachelor-, M. Sc.- and Ph. D.-students as well as distant adult students, university faculties, scientific researchers, college instructors and engineering staff.
Equal Channel Angular Extrusion (ECAE), sometimes referred to as Equal Channel Angular Pressing (ECAP), is a Severe Plastic Deformation technique. However the energy-power parameters of ECAE have not ...been fully addressed in previous known publications. The present article is focused on the punching pressure, accumulated plastic strain, and dead metal zone geometry estimation during ECAE of metal workpieces through a 2θ-die with a channel intersection angle of 2θ>0º and 2θ≠90º. Computational analytical results for ECAE technological parameters have been analytically derived for planar flow of a plastic, incompressible, non-hardening metal workpiece in an angular Segal die with 2θ>0º and 2θ≠90º. This is accomplished through the use of an Upper Bound Method (UBM) with Discontinuous Velocity Field (DVF) introduction. The development of the Dead Zone (DZ) for metal ECAE through a 2θ-die with 2θ>0º and 2θ≠90º has been analytically investigated. The obtained computational results for 2θ-die have been compared with the slip line analytic solutions of Segal for non-rectangular 2θ-dies of the same geometry. Good agreement between the two computational results has been found. The physical modeling techniques using plasticine have confirmed the appearance of a dead zone and material flow dynamics during ECAE through the Segal 2θ-die.
Better student understanding of the dynamic trends in graduate employment requires the development of the author's description of this multidisciplinary social problem.
This educational paper is ...focused on an author-proposed engineering-friendly description of oscillatory dynamics in the employment market for university graduates.
This didactical paper widely uses computational methods of oscillations theory, theory of electrical and hydraulic circuits as well as concepts of physical analogies and similarity.
The generalized character of the employment-related oscillations in the studied social system of employees was didactically enhanced through the original introduction of two technical analogies with similar oscillations in the electrical system of an LC-field-effect transistor oscillator and the mechanical system of a hydraulic ram pump.
The author-proposed triple physics-and-engineering analogy for the periodic oscillations in the socio-economic problem in graduate employment provides a broadening of the cross-disciplinary ideas of engineering students about oscillatory dynamics in the social, electrical and hydraulics systems. It was found in the case of the Donbass State Engineering Academy (Kramatorsk, Ukraine), that this original author's approach provides simultaneous enhancement of the cross-disciplinary undergraduate engineering curriculum in the courses of economics, management, higher education pedagogy, physics, hydraulics and electrical engineering.
The objective of this article is the description of advantages of a slanted die geometry, used for equal channel angular extrusion (ECAE) of materials. The prime novelty statement of the present ...research is an experimental flow pattern, obtained with circular gridlines and a numerical solution of a viscous flow 2D problem for the slanted die, derived with Navier–Stokes equations in curl transfer form. The geometry of the slanted die was chosen for the case of a rectangular die with channel intersection angle 2
θ =
90° and with parallel slants in the channel intersection zone, where the slant width is equal to the inlet and outlet channel widths. Computational material flow kinematics, macroscopic rotation patterns, material flow velocity fields, tangential stresses, and punching pressure fields during viscous materials ECAE have been derived with a numerical finite-difference solution of the curl transfer equation for 2D viscous flow of incompressible continuum during ECAE. Theoretical results have been verified with physical simulation experiments by the introduction of initial circular gridlines. Both theoretical and computational results confirm the suitability and technological advantages of dies with parallel slants over the known Segal and Iwahashi dies for ECAE, as slanted convergent dies enable the reduction of the dead zone size and provide the minimization of dangerous macroscopic rotation during ECAE processing of both metal and polymer materials.
The present article is focused on a 2D computational fluid mechanics study of local viscous flow dynamics and the formation character of rotary modes of deformation during Equal Channel Multiple ...Angular Extrusion (ECMAE) of a polymer workpiece fluid model through a U-shaped die with parallel slants in channel intersection zones. The present local flow problem was experimentally analyzed using physical simulation methods and theoretically studied with numerical fluid mechanics techniques. The computational approach has been grounded on the numerical finite difference solution of the boundary value problem for the Navier-Stokes equations in the curl transfer form for the local viscous flow of incompressible Newtonian fluid through a U-shaped rectangular die with parallel slants. The derived research results allow us to draw a conclusion that the implementation of a geometric design of parallel slants within a 2-turn U-shaped die results in localization of the maximum tangential stresses within the workpiece volume to the vicinity of these parallel slants during ECMAE.
A new mathematical model of a 3DOF 2D mechanical system “transported cross-beam, two moving bridge cranes” has been proposed. Small system oscillations have been derived through the introduction of ...Lagrange equations. The numerical estimation of 3DOF system motion has been carried out with equation-based Modelica language. The present article uses the Lagrange method and numerical and optimization methods, realized with JModelica.org and Optimica freeware. The absolute swaying of the cross-beam with respect to the displacement of the two moving bridge cranes was estimated. The phase portraits of the 3DOF system for linear and angular coordinates were presented. An open loop optimal control problem was posed for the motion of the bridge cranes. A “bang-bang” control strategy was implemented for the derivation of an optimal control solution, which enables the travel of two bridge cranes at a prescribed distance for minimum time and minimum swaying of a heavy cross-beam. The derived results of the numerical simulation can be easily practically realized by crane operators with good agreement with simple engineering estimations. The proposed control strategy enables synchronous motion of two bridge cranes with a cross-beam that practically solves the posed problem of unwanted excessive oscillations of a heavy cross-beam during transportation.
It is a common practice in pressure forming to make an Equal Channel Angular Extrusion (ECAE) of a workpiece through a die with channel intersection angle 2θ = 90° using a standard punch of brick or ...cylindrical shape with 2θ0 = 90°. However Nejadseyfi et al (2015) have applied a beveled 2θ0-punch to the process of ECAE through a standard angular die of Segal geometry with 2θ = 90° and 2θ0 ≠ 2θ. The scope of the article is focused on an alternative numerical study of Nejadseyfi-ECAE-Scheme using techniques of Computational Fluid Dynamics (CFD). A finite-difference method was applied to the numerical solution of the boundary value problem for the Navier-Stokes equations in the form of a vorticity transfer equation. The complex of 2D plots for CFD-derived fields of flow lines and flow velocities and 3D plots for spatial distributions of flow velocities and tangential stresses were firstly derived for Nejadseyfi-ECAE-Scheme during viscous flow of polymer workpiece models through angular die with 2θ = 90° for the different punch inclination angles 30° ≤ 2θ0 ≤ 150°. It was found that Nejadseyfi-ECAE-Scheme provides enhancement of the rotary modes of intensive deformations during ECAE. Results provide visualization of velocity gradients and macroscopic rotation and the illustration of Nejadseyfi et al’s ideas from an alternative CFD-based viewpoint.
A mathematical model of stress–strain behavior is developed for the process of powder wire flattening. Modeling was based on a partition of the deformation zone at a set of elementary volumes and a ...joint solution of the plasticity condition for porous materials and the equation of static equilibrium of forces within the elementary volume. The proposed mathematical model takes into account the real character of geometric parameter distributions as well as the complex of mechanical properties and conditions of contact friction along the length of the deformation zone. A distinctive feature of this model is an accounting for shell deformation in the deformation zone. This allowed us to define more precisely the plastic deformation zone and take into account the effect of shell bending on the energy-power parameters of the process. The experiments confirmed the validity of the assumptions and the shell influence on the process parameters. The proposed modeling approach provides the possibility to predict and optimize the parameters of an electrode material made by pressure working of powder wire. The derived results of the numerical simulation may be useful in improving the efficiency of the subsequent deposit welding operations.
Existing issues with student mental health are the sources of ongoing violation of academic and educational integrity in learning and instructional dynamics in all educational institutions worldwide.
...This didactical paper addresses the practical case of educational integrity violations induced by student mental illness. It presents a thought-provoking unified viewpoint of the existence of a non-obvious geometric analogy between the irreversible psycho-social process of mental disorder growth and the irreversible pressure forming-induced deformation process of materials extrusion through an angular domain.
This paper uses the method of geometric analogy between the dynamics of social irreversible processes in human society and technical irreversible processes in materials extrusion.
The novel analogy between the loss of elliptical shape of an initial circular material element within pressure-extruded material and the development of student mental inadequacy during intensive university education was firstly studied and analyzed in detail.
The author-proposed original socio-technical cross-disciplinary analogy improves and broadens student understanding of nonlinear dynamics both in the technical processes of macroscopic rotation formation in pressure-formed material and in the bio-social processes of psycho-neurological pathology development within a learner's mind.
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