2018 ◽  
Vol 1 (2) ◽  
pp. 97-114 ◽  
Author(s):  
M. Azizur Rahman ◽  
Mustafizur Rahman ◽  
A. Senthil Kumar

Microfabrication plays an active role in miniaturization of products and components in various emerging fields ranging from pharmaceuticals and bio-medical applications to electro-mechanical sensors and actuators to chemical microreactors and mechanical microturbines. Tool-based machining is one of the key technologies of microfabrication. The machining of materials on the micrometre and nanometre scales is fundamental for the fabrication of 3D micro components. However, there are limitations of scaling down the mechanical machining process from the macro- to micro- to nanoscales. Several factors that are not significant in conventional machining become significant in micro/nano-scale machining. This article identifies the important material-related issues on the evolution of micro cutting from conventional cutting process. The main focus is given to the state-of-the art micro/nano-cutting technologies of metal alloys with material perspective. Furthermore, a promising research of coupling the additive and subtractive manufacturing technologies has been highlighted to improve the surface quality of 3D-printed metallic parts.


Author(s):  
Bishwash Shrestha ◽  
Syed N. Ahsan ◽  
Matteo Aureli

In this paper, we report on a comprehensive experimental study on the fluid-structure interactions of a submerged rigid plate undergoing harmonic oscillations in a quiescent, Newtonian, viscous fluid. We conduct a detailed qualitative and quantitative analysis of the problem for broad ranges of oscillation parameters, including frequency and amplitude, to highlight the fluid-structure interaction mechanisms responsible for the hydrodynamic forces acting on the plate. The primary objective of this study is to understand the effect of the oscillation parameters on the resulting qualitative flow patterns and analyze their relation with vortex shedding and hydrodynamic forces. We classify different flow regimes depending on the behavior of the flow in the vicinity of the structure, with particular focus on vortex shedding and symmetry breaking phenomena, and analyze the forces in each regime by using particle image velocimetry and direct force measurement via a load cell. Comparison of the obtained experimental results against values predicted from numerical and semi-analytical models shows good agreement between our approach and the literature. Fundamental findings from this work have direct relevance to various engineering applications, including energy harvesting devices, biomimetic robotic system, and micro-mechanical sensors and actuators.


2007 ◽  
Vol 18 (2) ◽  
pp. 233-271 ◽  
Author(s):  
M. SCHINNERL ◽  
M. KALTENBACHER ◽  
U. LANGER ◽  
R. LERCH ◽  
J. SCHÖBERL

The dynamic behaviour of magneto-mechanical sensors and actuators can be completely described by Maxwell's and Navier-Lamé's partial differential equations (PDEs) with appropriate coupling terms reflecting the interactions of these fields and with the corresponding initial, boundary and interface conditions. Neglecting the displacement currents, which can be done for the classes of problems considered in this paper, and introducing the vector potential for the magnetic field, we arrive at a system of degenerate parabolic PDEs for the vector potential coupled with the hyperbolic PDEs for the displacements.Usually the computational domain, the finite element discretization, the time integration, and the solver are different for the magnetic and mechanical parts. For instance, the vector potential is approximated by edge elements whereas the finite element discretization of the displacements is based on nodal elements on different meshes. The most time consuming modules in the solution procedure are the solvers for both, the magnetical and the mechanical finite element equations arising at each step of the time integration procedure. We use geometrical multigrid solvers which are different for both parts. These multigrid solvers enable us to solve quite efficiently not only academic test problems, but also transient 3D technical magneto-mechanical systems of high complexity such as solenoid valves and electro-magnetic-acoustic transducers. The results of the computer simulation are in very good agreement with the experimental data.


2020 ◽  
Vol 56 (9) ◽  
pp. 5321-5427
Author(s):  
Frank Stein ◽  
Andreas Leineweber

AbstractLaves phases with their comparably simple crystal structure are very common intermetallic phases and can be formed from element combinations all over the periodic table resulting in a huge number of known examples. Even though this type of phases is known for almost 100 years, and although a lot of information on stability, structure, and properties has accumulated especially during the last about 20 years, systematic evaluation and rationalization of this information in particular as a function of the involved elements is often lacking. It is one of the two main goals of this review to summarize the knowledge for some selected respective topics with a certain focus on non-stoichiometric, i.e., non-ideal Laves phases. The second, central goal of the review is to give a systematic overview about the role of Laves phases in all kinds of materials for functional and structural applications. There is a surprisingly broad range of successful utilization of Laves phases in functional applications comprising Laves phases as hydrogen storage material (Hydraloy), as magneto-mechanical sensors and actuators (Terfenol), or for wear- and corrosion-resistant coatings in corrosive atmospheres and at high temperatures (Tribaloy), to name but a few. Regarding structural applications, there is a renewed interest in using Laves phases for creep-strengthening of high-temperature steels and new respective alloy design concepts were developed and successfully tested. Apart from steels, Laves phases also occur in various other kinds of structural materials sometimes effectively improving properties, but often also acting in a detrimental way.


Author(s):  
Dzung Viet Dao ◽  
Koichi Nakamura ◽  
Tung Thanh Bui ◽  
Susumu Sugiyama

Author(s):  
V. Saikumar ◽  
H. M. Chan ◽  
M. P. Harmer

In recent years, there has been a growing interest in the application of ferroelectric thin films for nonvolatile memory applications and as a gate insulator in DRAM structures. In addition, bulk ferroelectric materials are also widely used as components in electronic circuits and find numerous applications in sensors and actuators. To a large extent, the performance of ferroelectric materials are governed by the ferroelectric domains (with dimensions in the micron to sub-micron range) and the switching of domains in the presence of an applied field. Conventional TEM studies of ferroelectric domains structures, in conjunction with in-situ studies of the domain interactions can aid in explaining the behavior of ferroelectric materials, while providing some answers to the mechanisms and processes that influence the performance of ferroelectric materials. A few examples from bulk and thin film ferroelectric materials studied using the TEM are discussed below.Figure 1 shows micrographs of ferroelectric domains obtained from undoped and Fe-doped BaTiO3 single crystals. The domain boundaries have been identified as 90° domains with the boundaries parallel to <011>.


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