Tuning of Bandgap Structures in Three-Dimensional Kagome-Sphere Lattice

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Ying Liu ◽  
Xiu-zhan Sun ◽  
Wen-zheng Jiang ◽  
Yu Gu
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional ◽  
Structure Design ◽  
Geometrical Parameters ◽  
Geometrical Condition ◽  
Mass Spring Model ◽  
Sphere Radius ◽  
Equivalent Mass ◽  
Kagome Truss ◽  
Mass Spring

In this manuscript, acoustic wave propagation in a novel three-dimensional porous phononic crystal-Kagome lattice, is studied by using finite element method. Firstly, a Kagome-sphere structure is established based on Kagome truss. For lattice with fixed rods (sphere radius varied) or fixed spheres (rod radius varied), the band structures are calculated in order to clarify the influence of geometrical parameters (sphere and rod sizes) on the bandgap characteristics in Kagome-sphere lattice. The vibration modes at the band edges of the lowest bandgaps are investigated with the aim to understand the mechanism of the bandgap generation. It is found that the emergence of the bandgap is due to the local resonant vibration of the unit cell at the adjacent bands. The width and position of this bandgap can be tuned by adjusting the geometrical parameters. An equivalent mass-spring model is proposed and the equivalent system resonance frequency can be evaluated which predicts well the upper and lower edges of the complete bandgaps. Moreover, the critical geometrical parameter is formulated which gives the critical geometrical condition for the opening of the complete bandgaps. The results in this paper are relevant to the bandgap structure design of three-dimensional porous phononic crystals (PPCs).

scholarly journals Synthetic Weyl Points of the Shear Horizontal Guided Waves in One-Dimensional Phononic Crystal Plates

2021 ◽  
Vol 12 (1) ◽  
pp. 167
Author(s):  
Hongbo Zhang ◽  
Shaobo Zhang ◽  
Jiang Liu ◽  
Bilong Liu
Keyword(s):  
Guided Waves ◽  
Dimensional Space ◽  
Phononic Crystal ◽  
Phase Interface ◽  
Three Dimensional ◽  
Interface States ◽  
Geometrical Parameters ◽  
One Dimensional ◽  
Higher Dimensional ◽  
Shear Horizontal

Weyl physics in acoustic and elastic systems has drawn extensive attention. In this paper, Weyl points of shear horizontal guided waves are realized by one-dimensional phononic crystal plates, in which one physical dimension plus two geometrical parameters constitute a synthetic three-dimensional space. Based on the finite element method, we have not only observed the synthetic Weyl points but also explored the Weyl interface states and the reflection phase vortices, which have further proved the topological phase interface states. As the first realization of three-dimensional topological phases through one-dimensional phononic crystal plates in the synthetic dimension, this research demonstrates the great potential of applicable one-dimensional plate structural systems in detecting higher-dimensional topological phenomena.

scholarly journals Hydrodynamic aspects of moving vehicle with sloshing tanks

2018 ◽  
Vol 211 ◽  
pp. 15002
Author(s):  
Mengmeng Han ◽  
Jian Dai ◽  
Kok Keng Ang
Keyword(s):  
Analytical Solution ◽  
Domain Boundary ◽  
Spring Model ◽  
Potential Threat ◽  
Moving Vehicle ◽  
Mass Spring Model ◽  
Equivalent Mass ◽  
Modal Equation ◽  
Fitting In ◽  
Mass Spring

Freight vehicles with partially filled liquid tanks will be affected by liquid sloshing during transient motion. The sloshing induced by vehicle motion will lead to extra force on the vehicle and sometimes is a potential threat to safety. Previous studies on this problem usually use a mass-spring analogy to represent the sloshing effect of the liquid tank. Its main disadvantage is that CFD analysis or experimental study has to be performed beforehand, so that an equivalent mass-spring model can be constructed by curve fitting. In this paper, frequency domain boundary element method (BEM) and analytical solution to the sloshing problems are used to derive the modal equation and hydrodynamic parameters of the sloshing fluid. The accuracy of the results will be examined by comparison with available CFD results in the literature. The paper then evaluates the accuracy of equivalent mass-spring model and explores the possibility to approximate the sloshing effects inside cylindrical tanks by using analytical solution to the sloshing inside equivalent rectangular tanks.

scholarly journals Design and construction of multi-cylinder type liquid piston Stirling engine

2021 ◽  
Vol 313 ◽  
pp. 08003
Author(s):  
Prastowo Murti ◽  
Akira Takizawa ◽  
Eita Shoji ◽  
Tetsushi Biwa
Keyword(s):  
Preliminary Test ◽  
Acoustic Power ◽  
Stirling Engine ◽  
Geometrical Parameters ◽  
Test Results ◽  
Operation Temperature ◽  
Mass Spring Model ◽  
Mass Spring ◽  
Liquid Piston

In a multi-cylinder type liquid piston Stirling engine (MCLPSE), liquid columns in U-shaped tubes play the role of solid pistons in a mechanical Stirling engine. Besides the straightforward structure, advantages of the MCLPSE are a relatively low operation temperature difference below 100 K and use of harmless working fluids of air and water. This study presents a mass spring model for the MCLPSE, from which we determine geometrical parameters of MCLPSE to achieve a target acoustic power production under a given temperature condition. The preliminary test results will be presented.

Design Patterns of Soft Products Using Surface Flattening

2018 ◽  
Vol 18 (2) ◽  
Author(s):  
Dongliang Zhang ◽  
Jituo Li ◽  
Jin Wang
Keyword(s):  
Design Patterns ◽  
Three Dimensional ◽  
Optimization Method ◽  
Surface Flattening ◽  
Manufactured Products ◽  
Mass Spring Model ◽  
Boundary Optimization ◽  
Pattern Development ◽  
Mass Spring ◽  
Flattening Process

In this paper, we present a pattern development method for soft product design. We utilize a surface fattening method based on a mass-spring model to create 2D patterns unfolding from a three-dimensional (3D) model. Multilevel meshes are proposed to expedite the flattening process, and a boundary optimization method is employed to guarantee 2D patterns can be sewn well. We apply the proposed method to the design of real soft products. Experimental results show that it can deal with complex surfaces efficiently and robustly, and manufactured products are satisfactory.

A Three-Dimensional Lumped Parameter Model of Nanoscale Phononic Crystals

2009 ◽  
Author(s):  
Bruce L. Davis ◽  
Mahmoud I. Hussein
Keyword(s):  
Equations Of Motion ◽  
Three Dimensional ◽  
Phononic Crystals ◽  
Lumped Parameter Model ◽  
Lagrangian Equations ◽  
Area Of Interest ◽  
Simple Cubic ◽  
Lumped Parameter ◽  
Mass Spring Model ◽  
Mass Spring

This work focuses on modeling nanoscale phononic crystals by setting up the appropriate Lagrangian equations of motion. The atomic structure and force constants are accounted for by means of a lumped parameter mass-spring model. In particular we focus on a simple cubic lattice with one mass per primitive unit cell. We use the model to predict the wave propagation frequency spectrum. We then use the model to conduct a series of studies on the influence of defects intentionally introduced to the lattice at a supercell level. One area of interest is the effect of such alterations on the size and location of band gaps.

Modeling of Underwater Flexible Structures and Its Application to the Fishing Gear System Simulation

2004 ◽  
Author(s):  
Chun-Woo Lee ◽  
Ju-Hee Lee ◽  
Bong-Jin Cha ◽  
Hyun-Young Kim ◽  
Ji-Hoon Lee
Keyword(s):  
Flexible Structures ◽  
Three Dimensional ◽  
Stable Solution ◽  
Commercial Fishing ◽  
Flexible Systems ◽  
Physically Based Model ◽  
Mass Spring Model ◽  
Physically Based ◽  
External Forces ◽  
Mass Spring

This paper describes a physically based model for underwater flexible systems and presents its simulation results. In this study, a flexible structure is divided into a finite number of elements and those elements are connected with flexible lines. The elements of a structure can be modeled using the mass-spring model. The model is described as a nonlinear and stiff equation by considering the elasticity of the lines and external forces. The Newmark β method is used for the numerical integration of the system. It is found that this method offers low computational times and a stable solution. Also introduced is an algorithm to design various flexible systems using computer graphics, an automatic model creating system from the designed plan and a three-dimensional graphics tool that can show the calculated results. Application examples in design and simulation for the commercial fishing gears are presented.

Tuning of Acoustic Bandgaps in Phononic Crystals With Helmholtz Resonators

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jian-Bao Li ◽  
Yue-Sheng Wang ◽  
Chuanzeng Zhang
Keyword(s):  
Phononic Crystal ◽  
Three Dimensional ◽  
Helmholtz Resonator ◽  
Geometrical Parameters ◽  
Frequency Range ◽  
Acoustic Wave Propagation ◽  
Helmholtz Resonators ◽  
Lower Position ◽  
Narrow Bandgap ◽  
Lower Frequency Range

In this paper, acoustic wave propagation in a two- or three-dimensional phononic crystal consisting of Helmholtz resonators embedded in a fluid matrix is studied. The band structures are calculated to discuss the influence of the geometry topology of Helmholtz resonators on the bandgap characteristics. It is shown that a narrow bandgap will appear in the lower frequency range due to the resonance of the Helmholtz resonators. The width and position of this resonance bandgap can be tuned by adjusting the geometrical parameters of the Helmholtz resonator. The position of the resonance bandgap can be evaluated by the resonance frequency of the Helmholtz resonator. A decrease in the size of the opening generally results in a lower position and a smaller width of the bandgap. The system with one opening exhibits a wider bandgap in a lower position than the system with two openings.

scholarly journals Fast Overlap Detection between Hard-Core Colloidal Cuboids and Spheres. The OCSI Algorithm

Algorithms ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 72
Author(s):  
Luca Tonti ◽  
Alessandro Patti
Keyword(s):  
Colloidal Particles ◽  
Dynamic Properties ◽  
Wide Spectrum ◽  
Three Dimensional ◽  
Hard Core ◽  
Detection Algorithm ◽  
Three Dimensional Objects ◽  
Aggregation Behaviour ◽  
Sphere Radius ◽  
User Friendly

Collision between rigid three-dimensional objects is a very common modelling problem in a wide spectrum of scientific disciplines, including Computer Science and Physics. It spans from realistic animation of polyhedral shapes for computer vision to the description of thermodynamic and dynamic properties in simple and complex fluids. For instance, colloidal particles of especially exotic shapes are commonly modelled as hard-core objects, whose collision test is key to correctly determine their phase and aggregation behaviour. In this work, we propose the Oriented Cuboid Sphere Intersection (OCSI) algorithm to detect collisions between prolate or oblate cuboids and spheres. We investigate OCSI’s performance by bench-marking it against a number of algorithms commonly employed in computer graphics and colloidal science: Quick Rejection First (QRI), Quick Rejection Intertwined (QRF) and a vectorized version of the OBB-sphere collision detection algorithm that explicitly uses SIMD Streaming Extension (SSE) intrinsics, here referred to as SSE-intr. We observed that QRI and QRF significantly depend on the specific cuboid anisotropy and sphere radius, while SSE-intr and OCSI maintain their speed independently of the objects’ geometry. While OCSI and SSE-intr, both based on SIMD parallelization, show excellent and very similar performance, the former provides a more accessible coding and user-friendly implementation as it exploits OpenMP directives for automatic vectorization.

scholarly journals Energy Loss in Steep Open Channels with Step-Pools

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 72
Author(s):  
Suresh Kumar Thappeta ◽  
S. Murty Bhallamudi ◽  
Venu Chandra ◽  
Peter Fiener ◽  
Abul Basar M. Baki
Keyword(s):  
Energy Loss ◽  
Flow Rate ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Nonlinear Function ◽  
Open Channels ◽  
Geometrical Parameters ◽  
Transition Flow ◽  
Cumulative Energy ◽  
Zone Velocity

Three-dimensional numerical simulations were performed for different flow rates and various geometrical parameters of step-pools in steep open channels to gain insight into the occurrence of energy loss and its dependence on the flow structure. For a given channel with step-pools, energy loss varied only marginally with increasing flow rate in the nappe and transition flow regimes, while it increased in the skimming regime. Energy loss is positively correlated with the size of the recirculation zone, velocity in the recirculation zone and the vorticity. For the same flow rate, energy loss increased by 31.6% when the horizontal face inclination increased from 2° to 10°, while it decreased by 58.6% when the vertical face inclination increased from 40° to 70°. In a channel with several step-pools, cumulative energy loss is linearly related to the number of step-pools, for nappe and transition flows. However, it is a nonlinear function for skimming flows.

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