Three-Dimensional Analysis of Shape-Morphing Cantilever Oscillations in Viscous Fluids

2017 ◽  
Author(s):  
Syed N. Ahsan ◽  
Matteo Aureli
Keyword(s):  
Power Dissipation ◽  
Stokes Problem ◽  
Three Dimensional ◽  
Optimum Level ◽  
Power Losses ◽  
Linear Vibration ◽  
Shape Morphing ◽  
Propulsion Performance ◽  
Newtonian Viscous Fluid ◽  
Actuation Systems

In this paper, we study the linear flexural oscillations of a cantilever beam undergoing chord-wise shape-morphing deformation in a quiescent, Newtonian, viscous fluid. The shape-morphing deformation is prescribed for the beam cross section to an arc of a circle by specifying a periodic maximum curvature continuously along the axis of the structure. This particular strategy is investigated as a possible way to manipulate fluid-structure interaction mechanisms by modifying the hydrodynamic interactions in the vicinity of the submerged structure. Since we focus on the linear vibration of the beam, the fluid flow is described using three-dimensional unsteady Stokes hydrodynamics. By solving the linear unsteady Stokes problem in the frequency domain with a Stokeslet method, we identify the effect of the proposed shape-morphing strategy on the propulsion performance by estimating thrust, lift, and hydrodynamic power dissipation for a range of prescribed deformations. We verify the results obtained from our boundary element method against results from the existing literature. Our findings show a possible improvement in propulsion characteristics and minimization of hydrodynamic power dissipation, for an optimum level of shape-morphing deformation which is aspect ratio-dependent. Results from this study can aid in designing and operating cantilever-based underwater actuation systems for which the multi-objective goal of power losses reduction and propulsion performance improvement is sought.

Minimization of Hydrodynamic Power Losses in Oscillating Submerged Structures by a Novel Shape-Morphing Strategy

2016 ◽  
Author(s):  
Syed N. Ahsan ◽  
Matteo Aureli
Keyword(s):  
Power Dissipation ◽  
Flexible Structures ◽  
Energy Losses ◽  
Moving Wall ◽  
Shape Morphing ◽  
Computational Fluid Dynamics Simulations ◽  
Expenditure Reduction ◽  
Newtonian Viscous Fluid ◽  
Dynamics Simulations ◽  
Interaction Problem

In this paper, we investigate the two dimensional fluid-structure interaction problem of the oscillation of a shape-morphing plate in a quiescent, Newtonian, viscous fluid. The plate is considered as a moving wall for the fluid undergoing two concurrent periodic motions: a rigid oscillation along its transverse direction coupled to a shape-morphing deformation to an arc of a circle with prescribed maximum curvature. Differently from studies concerned with passive flexible structures, here, we introduce the prescribed deformation to specifically manipulate vortex-shedding and modulate hydrodynamic forces and energy losses during underwater oscillations. Computational fluid dynamics simulations are performed to evaluate the effect of the prescribed deformation strategy on the added mass and damping effect along with the hydrodynamic power dissipation. We observe that a minimum in the hydrodynamic power dissipation exists for an optimum curvature of the plate. This finding may allow significant power expenditure reduction in underwater vibrating systems where minimization of energy losses or maximization of quality factor are desirable.

scholarly journals Transient Thermal Analysis of NH000 gG 100A Fuse Link Employing Finite Element Method

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1421
Author(s):  
Michał Szulborski ◽  
Sebastian Łapczyński ◽  
Łukasz Kolimas ◽  
Łukasz Kozarek ◽  
Desire Dauphin Rasolomampionona ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Ceramic Body ◽  
Three Dimensional ◽  
Operating Mode ◽  
Power Losses ◽  
Empirical Tests ◽  
Transient Thermal ◽  
Different Parts ◽  
Element Method

In this paper, a detailed three-dimensional, transient, finite element method of fuse link NH000 gG 100 A is proposed. The thermal properties during the operation of the fuses under nominal (100 A) and custom conditions (110 and 120 A) are the main focus of the analyses that were conducted. The work concerns both the outside elements of the fuse link (ceramic body) and the elements inside (current circuit). Both the distribution of the electric current and its impact on the temperature of the construction parts of the fuses during their operating mode have been described. Temperature distribution, power losses and energy dissipation were measured using a numerical model. In order to verify and validate the model, two independent teams of scientists executed experimental research, during which the temperature was measured on different parts of the device involving the rated current. Finally, the two sets of results were put together and compared with those obtained from the simulation tests. A possible significant correlation between the results of the empirical tests and the simulation work was highlighted.

scholarly journals A Framework for Approximation of the Stokes Equations in an Axisymmetric Domain

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Niklas Ericsson
Keyword(s):  
Fourier Expansion ◽  
Stokes Equations ◽  
Stokes Problem ◽  
Three Dimensional ◽  
Countable Family ◽  
Angular Variable ◽  
Two Dimensional ◽  
Sobolev Norms ◽  
Well Posed ◽  
Variational Formulations

Abstract We develop a framework for solving the stationary, incompressible Stokes equations in an axisymmetric domain. By means of Fourier expansion with respect to the angular variable, the three-dimensional Stokes problem is reduced to an equivalent, countable family of decoupled two-dimensional problems. By using decomposition of three-dimensional Sobolev norms, we derive natural variational spaces for the two-dimensional problems, and show that the variational formulations are well-posed. We analyze the error due to Fourier truncation and conclude that, for data that are sufficiently regular, it suffices to solve a small number of two-dimensional problems.

Stabilized hp-DGFEM for Incompressible Flow

2003 ◽  
Vol 13 (10) ◽  
pp. 1413-1436 ◽  
Author(s):  
D. Schötzau ◽  
C. Schwab ◽  
A. Toselli
Keyword(s):  
Boundary Layer ◽  
Discontinuous Galerkin ◽  
Incompressible Flow ◽  
Discontinuous Galerkin Methods ◽  
Stokes Problem ◽  
Three Dimensional ◽  
Stability Result ◽  
Approximation Order ◽  
Galerkin Methods ◽  
Aspect Ratios

We consider stabilized mixed hp-discontinuous Galerkin methods for the discretization of the Stokes problem in three-dimensional polyhedral domains. The methods are stabilized with a term penalizing the pressure jumps. For this approach it is shown that ℚk-ℚk and ℚk-ℚk-1 elements satisfy a generalized inf–sup condition on geometric edge and boundary layer meshes that are refined anisotropically and non quasi-uniformly towards faces, edges, and corners. The discrete inf–sup constant is proven to be independent of the aspect ratios of the anisotropic elements and to decrease as k-1/2 with the approximation order. We also show that the generalized inf–sup condition leads to a global stability result in a suitable energy norm.

A theoretical and experimental investigation into the vibration response of a flexible rotor and squeeze-film damper assembly

2001 ◽  
Vol 215 (10) ◽  
pp. 1251-1269 ◽  
Author(s):  
C-C Siew ◽  
M Hill ◽  
R Holmes ◽  
M Brennan
Keyword(s):  
Harmonic Balance ◽  
Three Dimensional ◽  
Harmonic Balance Method ◽  
Vibration Response ◽  
Mode Shapes ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Linear Vibration ◽  
Squeeze Film Damper ◽  
Good Agreement

This paper presents two efficient methods to calculate the unbalance vibration response of a flexible rotor provided with a squeeze-film damper (SFD) with retainer springs. Both methods are iterative and combine the harmonic balance and receptance approaches. The first method, called the modified iteration method (MIM), is suitable for predicting the three-dimensional mode shapes of a concentric SFD-rotor system. The second method, called the modified harmonic balance method (MHBM), is developed to calculate the non-linear vibration response of a flexible shaft provided with either a concentric or eccentric SFD. The system is also investigated experimentally under different conditions. The predictions computed by these methods are compared with experimental measurements and reasonably good agreement is obtained.

scholarly journals Divergent Design of Mechanical Metamaterials Clan Deducted from Arc-serpentine Curve

2021 ◽  
Author(s):  
Shengli Mi ◽  
Hongyi Yao ◽  
Xiaoyu Zhao ◽  
Wei Sun
Keyword(s):  
Thick Plate ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Design Strategies ◽  
Shape Morphing ◽  
Mechanical Metamaterials ◽  
Unit Cells ◽  
Combinatorial Principles ◽  
Composite Curve ◽  
Typical Design

Abstract The exotic properties of mechanical metamaterials are determined by their unit-cells' structure and spatial arrangement, in analogy with the atoms of conventional materials. Companioned with the mechanism of structural or cellular materials1–5, the ancient wisdom of origami6–11 and kirigami12–16 and the involvement of multiphysics interaction2,17,18 enrich the programable mechanical behaviors of metamaterials, including shape-morphing8,12,14,16,19, compliance4,5,8,17,20, texture2,18,21, and topology11,18,22−25. However, typical design strategies are mainly convergent, which transfers various structures into one family of metamaterials that are relatively incompatible with the others and do not fully bring combinatorial principles3,10,26 into play. Here, we report a divergent strategy that designs a clan of mechanical metamaterials with diverse properties derived from a symmetric curve consisting of serpentines and arcs. We derived this composite curve into planar and cubic unit-cells and modularized them by attaching magnetics. Moreover, stacking each of them yields two- and three-dimensional auxetic metamaterials, respectively. Assembling with both modules, we achieved three thick plate-like metamaterials separately with flexibility, in-plane buckling, and foldability. Furthermore, we demonstrated that the hybrid of paradox properties is possible by combining two of the above assembles. We anticipate that this divergent strategy paves the path of building a hierarchical library of diverse combinable mechanical metamaterials and making conventional convergent strategies more efficient to various requests. Main

Fast Thermal Analysis of Vertically Integrated Circuits (3-D ICs) Using Power Blurring Method

2009 ◽  
Author(s):  
Je-Hyoung Park ◽  
Ali Shakouri ◽  
Sung-Mo Kang
Keyword(s):  
Integrated Circuits ◽  
Power Dissipation ◽  
Three Dimensional ◽  
Computation Time ◽  
Maximum Error ◽  
3D Ic ◽  
Additional Advantage ◽  
3D Ics ◽  
Ic Technology ◽  
Power Blurring

CMOS VLSI technology has been facing various technical challenges as the feature sizes scale down. To overcome the challenges imposed by the shrink of the conventional on-chip interconnect system in IC chips, alternative interconnect technologies are being developed: one of them is three dimensional chips (3D ICs). Even though 3D IC technology is a promising solution for interconnect bottlenecks, thermal issues can be exacerbated. Thermal-aware design and optimization will be more critical in 3D IC technology than conventional planar IC technology, and hence accurate temperature profiles of each active layer will become very important. In 3D ICs, temperature profile of one layer depends not only on its own power dissipation but also on the heat transferred from other layers. Thus, thermal considerations for 3D ICs need to be done in a holistic manner even if each layer can be designed and fabricated individually. Conventional grid-based temperature computation methods are accurate but are computationally expensive, especially for 3D ICs. To increase computational efficiency, we developed a matrix convolution technique, called Power Blurring (PB) for 3D ICs. The temperature resulting from any arbitrary power dissipation in each layer of the 3D chip can be computed quickly. The PB method has been validated against commercial FEA software, ANSYS. Our method yields good results with maximum error less than 2% for various case studies and reduces the computation time by a factor of ∼ 60. The additional advantage is the possibility to evaluate different power dissipation profiles without the need to re-mesh the whole 3D chip structure.

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