Accepted Date: 2022-01-24
Optimal fail-safe truss structures: new solutions and uncommon characteristics
James Kirby, Shiwei Zhou, Yi Min Xie
Abstract
To investigate the characteristics of optimal fail-safe structures subjected to single and multi-member damage scenarios, we consider a pin-jointed cantilever truss with all members directly connected from the load point to the boundary. Two problem formulations are considered - minimizing the compliance with a volume constraint and minimizing the volume with stress constraints. Whilst these formulations produce equivalent structures for traditional truss design problems, we find that this is no...
Accepted Date: 2022-01-20
Reconstructing the neutrally-buoyant particle flow near a singular corner
Francesco Romano
Abstract
The correction of buoyancy effects is tackled for particles moving close to a singular corner in creeping flow conditions. A few density-mismatched particle trajectories are used to reconstruct the dynamics of a neutrally-buoyant particle all over the target domain. We propose to take advantage of the dissipative dynamics of density-mismatched particles in order to probe the target domain. Thereafter, we retrieve the neutrally-buoyant particle flow all over the domain by reconstructing the phase...
Accepted Date: 2022-01-18
A fast mapping method to evaluate immersed boundary hydrodynamic forces
Shi-Jun Li, Jun-Hua Pan, Ming-Jiu Ni
Abstract
Immersed boundary method is a crucial method to deal with particle suspension flow. Particle shapes involved in such flow are usually simple geometry, such as sphere and ellipsoid, which can be conveniently represented by the triangular surface grid. When the number of particles and resolution of the surface grid increase, calculating the hydrodynamic force on the particle surface through integration can be time-consuming. Hence, the present paper establishes a fast mapping method to evaluate im...
Accepted Date: 2022-01-14
Experimental study on the motion of a spherical particle in a plane traveling sound wave
Dongmei Wan, Haitao Xu
Abstract
We present an experimental study on the motion of a spherical droplet in a plane traveling sound wave. The experiments were performed in the test section of a tunnel with two loudspeakers at the two ends of the tunnel. By adjusting the amplitude ratio and the phase difference between the two speakers, a plane traveling sound wave field can be achieved in the test section of the tunnel, which we checked by measuring the amplitudes and phases of the sound pressure along the tunnel and by simultane...
Accepted Date: 2022-01-13
Investigation of hysteresis effect of cavitating flow over a pitching Clark-Y hydrofoil
Zhang Mengjie, Feng Fuyong, Wang Meijing, Guo Zhipu, Kang Zhong, Huang Biao
Abstract
The objective of this paper is to investigate the hysteresis effect of cavitating flow over a Clark-Y hydrofoil undergoing a transient pitching motion at Reynolds number Re=4.55×105, cavitation number σ=1.33, pitching frequency f*=2Hz via combined experimental and numerical studies. A hysteresis phenomenon is observed in hydrodynamic curve and cavity area in increasing and decreasing of angle of attack α. The hydrodynamic curves are divided into three regions: Region A, Region B and Region C. Fo...
Accepted Date: 2022-01-11
Active control of vortex-induced vibration of a circular cylinder by using the oscillatory plate immersed in the cylinder wake at low Reynolds number
Yiming Ren, Zhiqiang Xin, Shuitao Gu
Abstract
As a typical fluid Fluid-Solid Interaction problem, vortex-induced vibration (VIV) is common in engineering, so it is vital to study its control mechanism. Numerical simulations of the active control of vortex-induced vibration of a cylinder are carried out in this study. The splitter plate with harmonic oscillation is used as the control device for the dynamic response of the cylinder. The displacement response, lift and drag coefficient, and vibration frequency of the cylinder, energy efficien...
Accepted Date: 2022-01-10
On the some issues of particle motion in the flow of viscoelastic fluids
Zhenna Li, Jianzhong Lin
Abstract
Particle motion in confined shear flow of viscoelastic fluids is very common in nature and has a wide range of applications. Understanding and mastering the motion characteristics of particles in viscoelastic fluids has important academic value and practical significance. In this paper, we first introduce the related equations and characteristic parameter, and then emphasize the following issues: the lateral equilibrium position of particle; interaction and aggregation of multiple particles; the...
Accepted Date: 2022-01-10
Opponent Cart-Pole Dynamics for Reinforcement Learning of Competing Agents
Xun Huang
Abstract
In this work, the classical single cart-pole dynamic system is extended to the double cart-pole dynamic system with the inclusion of a competing target, which enables the study of multi-agent deep learning problems at an affordable cost. The corresponding important issues, such as system dynamics, reward function and simultaneous training of opponent agents, are discussed in details. To showcase the system dynamics, a couple of agents are trained and the analysis of the competing results reveals...
Accepted Date: 2022-01-07
Axisymmetric 3:1 internal resonance of thin-walled hyperelastic cylindrical shells under both axial and radial excitations
Jia Jiao, Jie Xu, Xuegang Yuan, Li-Qun Chen
Abstract
Nonlinear vibration with axisymmetric 3:1 internal resonance is investigated for an incompressible neo-Hookean hyperelastic cylindrical shell under both axial and radial harmonic excitations. A full nonlinear strain-displacement relation is derived from the large deflection theory of thin-walled shells. A set of nonlinear differential equations describing the large deflection vibration are formulated by the Lagrange equation and the assumption of small strains. Steady-state responses of the syst...
Accepted Date: 2022-01-04
Experimental study of the high-frequency instability in the hypersonic boundary layer over a cone at 6° angle of attack
Haibo Niu, Shihe Yi, Xiaolin Liu, Wenpeng Zheng, Xiaoge Lu
Abstract
The high-frequency instability on a cone at 6? angle of attack is measured in a hypersonic quiet wind tunnel with Reynolds number of 6.90× 106 m?1, and Mach number is 6. Fast-response pressure sensors are used to measure the disturbance waves on the surface of the cone. The nano-tracer-based planar laser cattering (NPLS) technique is used to visualize the coherent structures of the three-dimensional boundary layer. At the plane of azimuthal angle of θ =30? from the leeward ray, low-frequency and...
Accepted Date: 2021-12-29
Dynamically compressive behaviors and plastic mechanisms of a CrCoNi medium entropy alloy at various temperatures
Kun Jiang, Jianguo Li, Bin Gan, Tian Ye, Lianyang Chen, Tao Suo
Abstract
As an attractive class of metallic materials, single-phase CrCoNi medium-entropy alloy (MEA) has drawn much attention recently regarding to their deformation behaviors, but the dynamically mechanical responses of this alloy at high strain rates remain less studied, especially coupled with extremely low temperatures. In this study, the dynamic deformation behaviors of this CrCoNi MEA were systematically investigated at room temperature (RT=298 K) and liquid nitrogen temperature (LNT=77 K) using t...
Accepted Date: 2021-12-27
Evaluation of machine learning algorithms for predictive Reynolds stress transport modeling
J P PANDA, H V WARRIOR
Abstract
The application of machine learning (ML) algorithms to turbulence modeling have shown promise over the last few years, but their application has been restricted to eddy viscosity based closure approaches. In this article, we discuss the rationale for the application of machine learning with high-fidelity turbulence data to develop models at the level of Reynolds stress transport modeling. Based on these rationales we compare different machine learning algorithms to determine their efficacy and r...
Accepted Date: 2021-12-27
Effect of gauge corner lubrication on wheel/rail non-Hertzian contact and rail surface RCF on the curves
Yunfan Yang, Xinru Guo, Liang Ling, Kaiyun Wang, Wanming Zhai
Abstract
Wheel/rail rolling contact is a highly non-linear issue that affected by the complicated operating environment (including adhesion conditions and motion attitude of train and track system), which is a fundamental topic for the further insight into wheel/rail tread wear and rolling contact fatigue (RCF). The rail gauge corner lubrication (RGCL) devices have been installed on metro outer rail with an aim to mitigating its wear on the curved tracks. This paper presents an investigation into the inf...
Accepted Date: 2021-12-21
Biomimicking and Evaluation of Dragonfly Wing Morphology with Polypropylene Nanocomposites
Vivek Khare, Sudhir Kamle
Abstract
Dragonfly hindwing inspired two different flapping wing morphologies are investigated for flexible flapping wing micro air vehicles (FWMAV) applications. The Wing skin is developed using 1% functionalized carbon nanotubes reinforced polypropylene nanocomposites with carbon fiber epoxy composite strands as venation pattern. The resonance frequencies are the fundamental information for biomimicking and were calculated theoretically from stiffness data. Bending dominated first natural frequency was...
Accepted Date: 2021-12-20
Topological bound states in elastic phononic plates induced by disclinations
Baizhan Xia, Zihan Jiang, Liang Tong, Shengjie Zheng, Xianfeng Man
Abstract
Topological defects (including disclinations and dislocations) which commonly exist in various materials have shown an amazing ability to produce excellent mechanical and physical properties of matters. In this paper, disclinations are introduced into topological nontrivial elastic phononic plates. The deformation of the lattice yielded by disclinations produces a pentagonal core with the local five-fold symmetry. The topological bound states are well localized around the boundaries of the penta...
Accepted Date: 2021-12-17
Vibration Characteristics Analysis of Tank Gun Barrel with Non-uniform Cross-section
Xun Wang, Xiaoting Rui, Jinghong Wang, Jianshu Zhang, Genyang Wu, Junjie Gu
Abstract
The firing accuracy of a tank gun is affected significantly by the flexural motion of the barrel. For purpose of satisfying the requirement of efficiently and accurately dynamic analysis and optimization of the tank gun barrel to ensure it has good dynamic characteristics and firing accuracy, the high-fidelity dynamics model of a tank gun barrel is developed according to the transfer matrix method for multibody system which has features of high degree of stylization and high computational speed....
Accepted Date: 2021-12-16
Mechanosensation of osteocyte with collagen hillocks and primary cilia under pressure and electric field stimulation
Yan Wang, Chaoxin Li,Hao Dong, Jianhao Yu, Yang Yan, Xiaogang Wu, Yanqin Wang, Pengcui Li, Xiaochun Wei,Weiyi Chen
Abstract
Mechanosensors are the most important organelles for osteocytes to perceive the changes of surrounding mechanical environment. To evaluate the biomechanical effectiveness of collagen hillock, cell process and primary cilium in lacunar-canalicular system (LCS), we developed pressure-electricity-structure interaction models by using the COMSOL Multiphysics software to characterize the deformation of collagen hillocks- and primary cilium-based mechanosensors in osteocyte under fluid flow and electr...
Accepted Date: 2021-12-14
Dynamics analysis of higher-order soliton solutions for the coupled mixed derivative nonlinear Schrodinger equation
Kai Zhang,Fang Hong,Jie Luo,Zichen Deng
Abstract
In this paper, the dynamics of the higher-order soliton solutions for the coupled mixed derivative nonlinear Schr?dinger equation are investigated via generalized Darboux transformation. Given a pair of linearly independent solutions of the Lax pair, the one- to three- soliton solutions are obtained via algebraic iteration. Furthermore, two and three solitons are respectively displayed via numerical simulation. Moreover, the dynamics of solitons are illustrated with corresponding evolution plots...
Accepted Date: 2021-12-14
A solution strategy combining the mode superposition method and time integration methods for linear dynamic systems
Yufeng Xing, Lu Yao, Yi Ji
Abstract
In this article, the mode superposition method is combined with a time integration method like the trapezoidal rule to improve solution accuracy for linear dynamic systems. In this combination strategy, an essential thing is to decompose a dynamic system into two sub-systems, a small-scale low-frequency system and a high-frequency system. The former can be analytically and efficiently solved with the mode superposition method, and the latter is dealt with through a time integration method such a...
Accepted Date: 2021-12-11
Topology optimization of magnetorheological smart materials included PnCs for tunable wide bandgap design
Kuan Liang, Jingjie He, Zhiyuan Jia, Xiaopeng Zhang
Abstract
Design and application of tunable phononic crystals (PnCs) are attracting increasing interest due to their promising capabilities to effectively manipulate acoustic and elastic waves. This paper investigates topology optimization of the magnetorheological (MR) materials included PnCs for opening the tunable and wide bandgaps. Therein, the bandgap tunability of the PnCs is achieving by shear modulus variation of MR Materials under continuously changing applied magnetic field. The pseudo elemental...
Accepted Date: 2021-12-06
Small symmetrical deformation and stress analysis of catenary shells of revolution
Bo-Hua Sun
Abstract
The catenary shells of revolution are widely used in church constructions due to their unique mechanics' feature. To have a better understanding of the deformation and stress of the catenary shells of revolution, we formulate the principal radii for two kinds of catenary shells of revolution and their displacement type governing equations. Numerical simulations are carried out based on both Reissner-Meissner mixed formulations and displacement formulations. Our investigations show that both defo...
Accepted Date: 2021-12-02
Failure behavior and criteria of metallic glasses
Y. Chen, L.H. Dai
Abstract
Metallic glasses (MGs) constitute an emerging class of materials with excellent properties envisaged for functional and structural applications. However, the brittle failure at room temperature and resultant complicate fracture behavior greatly limit their wide engineering applications. Over the past decades, the deformation and fracture in ductile or brittle mode referring to material compositions, load conditions, sample size, etc., have been widely studied, and significant progress has been m...
Accepted Date: 2021-12-02
Extreme transmission of elastic metasurface for deep subwavelength focusing
Mu Jiang, Hong-Tao Zhou, Xiao-Shuang Li, Xiao-Wen Fu, Yan-Feng Wang, Yue-Sheng Wang
Abstract
In this paper, elastic metasurfaces composed of zigzag units are proposed to manipulate flexural waves at a deep subwavelength scale. Through the parameter optimization of genetic algorithm, units with full transmission and full phase control can be found, while the width is only one fifth of the wavelength. The outstanding capability of the units is explained by analyzing their wave fields. The flat and the curved metasurfaces for focusing are designed and simulated, showing excellent performan...
Accepted Date: 2021-11-27
Nonlinear size-dependent dynamic instability and local bifurcation of FG nanotubes transporting oscillatory fluids
Qiduo Jin, Yiru Ren
Abstract
Oscillation of fluid flow may cause the dynamic instability of nanotubes, which should be valued in the design of nano electromechanical system. Nonlinear dynamic instability of the fluid-conveying nanotube transporting the harmonic pulsating flow is studied. The nanotube is composed of two surface layers made of functionally graded materials and a viscoelastic interlayer. The nonlocal strain gradient model coupled with surface effect is established based on the Gurtin-Murdoch's surface elastici...
Accepted Date: 2021-11-24
Algebraic equations and non-integer orders of fractal operators abstracted from biomechanics
Yajun Yin, Gang Peng, Xiaobin Yu
Abstract
Previous study implies that the fractional operator may stem from the motion in fractal space or the motion of fractal structure abstracted from biological systems. This study is devoted to answering another essential question, i.e. what determines the order of the fractional operator in fractal structure? To answer this question, this paper generalizes the concept of fractal cell defined in the previous paper, explores the tree-like and net-like fractal structures with higher-order topology, ab...
Accepted Date: 2021-11-24
Knockdown factor of buckling load for axially compressed cylindrical shells: State of the art and new perspectives
Bo Wang, Peng Hao, Xiangtao Ma, Kuo Tian
Abstract
Thin-walled structures are commonly utilized in the aerospace and aircraft structures, which are prone to buckling under the axial compression and extremely sensitive to geometric imperfections. After decades of efforts, it still remains a challenging issue to accurately predict the lower-bound buckling load due to the impact of geometric imperfections. Up to now, the lower-bound curve in NASA SP-8007 is still widely used as the design criterion of aerospace thin-walled structures, and this seri...
Accepted Date: 2021-11-24
Modeling of the turbulent burning velocity for planar and Bunsen flames over a wide range of conditions
Zhen Lu, Yue Yang
Abstract
We develop and assess a model of the turbulent burning velocity sT over a wide range of conditions. The aim is to obtain an explicit sT model for turbulent combustion modeling and flame analysis. The model consists of sub models of the stretch factor and the turbulent flame area. The stretch factor characterizes the flame response of turbulence stretch and incorporates effects of detailed chemistry and transport with a lookup table of laminar counterflow flames. The flame area model captures the...
Accepted Date: 2021-11-24
On the effectiveness of local vortex identification criteria in the vortex representation of wall-bounded turbulence
Chengyue Wang, Qi Gao, Tianle Chen, Biao Wang
Abstract
Compressing complex flows into a tangle of vortex filaments is the basic implication of the classical vortex-representation notion. This work focuses on the effectiveness of the local identification criteria in the vortex representation of wall-bounded turbulence. Basically, five local identification criteria regarding vortex strength and three criteria for vortex axis are considered. Instead of separately evaluating the two classes of criteria, the current work defines vortex vectors by arbitra...
Accepted Date: 2021-11-23
Effect of blowing ratio on the relaminarization phenomenon over convex curved wall
Wei-Yi Su, Feng-Rui Zhang, Mou‐Yuan Wang
Abstract
Relaminarization is a reverse transition from turbulent state to laminar or laminar-like state as the turbulent boundary layer is accelerated, which cause the boundary layer easy to separate under the adverse pressure gradient. To investigate the mechanism of relaminarization flow control with air injection, large eddy simulations were performed for a turbulent flow over a convex curved wall at Mach number 3.0 under different blowing ratios. The results show that the acceleration has markedly re...
Accepted Date: 2021-11-22
Fracture behavior of granite specimen containing a single fissure under uniaxial compression by GBM3D
Wen-Ling Tian, Sheng-Qi Yang, Yan-Hua Huang, Zhi-Jin Dong
Abstract
The understanding of the mechanical behavior of granite containing fissures is of great significance for geothermal energy exploitation and high-level nuclear waste disposal repository. To consider the grain interlocking and rotational resistance behavior in granite specimens, the GBM3D was constructed to investigate the fracture behavior of granite specimens containing a single fissure. The numerical result indicates that this GBM3D can be used to investigate the mechanical behavior of granite ...