Architectural Synthesis and Analysis of Dual-Cellular Fluidic Flexible Matrix Composites for Multifunctional Metastructures

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Suyi Li ◽  
K. W. Wang
Keyword(s):  
Cellular Structure ◽  
Large Scale ◽  
Equations Of Motion ◽  
Variable Stiffness ◽  
Cell Stiffness ◽  
Matrix Composites ◽  
Vibration Absorption ◽  
Design And Synthesis ◽  
Mechanical Constraints ◽  
The Rich

Recently, a cellular structure concept based on fluidic flexible matrix composites (F2MCs) was investigated for its potential of concurrently achieving multiple adaptive functions. Such structure consists of two fluidically connected F2MC cells, and it has been proven capable of dynamic actuation with enhanced authority, variable stiffness, and vibration absorption. The purpose of the research presented in this paper is to develop comprehensive design and synthesis tools to exploit the rich functionality and versatility of this F2MC based system. To achieve this goal, two progressive research topics are addressed: The first is to survey unique architectures based on rigorous mathematical principles. Four generic types of architectures are identified for the dual-cellular structure based on fluidic and mechanical constraints between the two cells. The system governing equations of motion are derived and experimentally tested for these architectures, and it is found that the overall structural dynamics are related to the F2MC cell stiffness, internal pressure difference, and static flow volume between the two cells according to the architectural layout. The second research topic is to derive a comprehensive synthesis procedure to assign the F2MC designs so that the cellular structure can simultaneously reach a set of different performance targets. Synthesis case studies demonstrate the range of performance of the F2MC based cellular structure with respect to different architectures. The outcome of this investigation could provide valuable insights and design methodologies to foster the adoption of F2MC to advance the state of art of a variety of engineering applications. It also lays the foundation for a large-scale “metastructure,” where many pairs of fluidically connected F2MC can be employed as modules to achieve synergetic global performance.

Switched Stiffness Vibration Controllers for Fluidic Flexible Matrix Composites

2009 ◽  
Author(s):  
Amir Lotfi-Gaskarimahalle ◽  
Christopher D. Rahn
Keyword(s):  
Equations Of Motion ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Variable Stiffness ◽  
Flow Coefficient ◽  
Step Response ◽  
Semiactive Control ◽  
Matrix Composites ◽  
Mass System ◽  
3D Elasticity

This paper investigates semi-active vibration control using Fluidic Flexible Matrix Composites (F2MC) as variable stiffness components of flexible structures. The stiffness of F2MC tubes can be dynamically switched from soft to stiff by opening and closing an on/off valve. Fiber reinforcement of the F2MC tube changes the internal volume when externally loaded. With an open valve, the fluid in the tube is free to move in or out of the tube, so the stiffness is low. When the valve is closed, the high bulk modulus fluid resists volume change and produces high stiffness. The equations of motion of an F2MC-mass system is derived using a 3D elasticity model and the energy method. The stability of the unforced dynamic system is proven using a Lyapunov approach. To capture the important system parameters, nondimensional full order and reduced order models are developed. A Zero Vibration (ZV) state switch technique is introduced that suppresses vibration in finite time, and is compared to conventional Skyhook semiactive control. The ITAE performance of the controllers is optimized by adjusting the open valve flow coefficient. Simulation results show that the optimal ZV controller outperforms the optimal Skyhook controller by 13% and 60% for impulse and step response, respectively.

Stiffness Shaping for Zero Vibration Fluidic Flexible Matrix Composites

2008 ◽  
Author(s):  
Amir Lotfi-Gaskarimahalle ◽  
Ying Shan ◽  
Suyi Li ◽  
Christopher D. Rahn ◽  
Charles E. Bakis ◽  
...  
Keyword(s):  
Equations Of Motion ◽  
Active Vibration Control ◽  
Variable Stiffness ◽  
Matrix Composites ◽  
Mass System ◽  
Apparent Stiffness ◽  
Active Vibration ◽  
3D Elasticity ◽  
High Bulk ◽  
Orifice Valve

This paper studies semi-active vibration control using Fluidic Flexible Matrix Composites (F2MC) as variable stiffness structures. The apparent stiffness of F2MC tubes can be changed using a variable orifice valve. With fiber reinforcement, the volume inside the tube may change with external load. With an open valve, the liquid is free to move in or out of the tube, so the apparent stiffness will not changed. When the valve is closed, the high bulk modulus liquid is confined, which resists the volume change and causes the apparent stiffness of the tube to increase. The equations of motion of an F2MC-mass system is derived using a 3D elasticity model and the energy method. A reduced order model is then developed for fully-open or fully-closed valves. A Skyhook valve that cycles the valve between open and closed, asymptotically decays the vibration. A Zero Vibration (ZV) Stiffness Shaping technique is introduced to suppress the vibration in finite time. A sensitivity analysis of the ZV Stiffness Shaper studies the robustness to parameteric uncertainties.

scholarly journals A Variable Parameter Ambient Vibration Control Method Based on Quasi-Zero Stiffness in Robotic Drilling Systems

Machines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 67
Author(s):  
Laixi Zhang ◽  
Chenming Zhao ◽  
Feng Qian ◽  
Jaspreet Singh Dhupia ◽  
Mingliang Wu
Keyword(s):  
Vibration Control ◽  
Vibration Isolation ◽  
Control Method ◽  
Control Strategies ◽  
Equations Of Motion ◽  
Variable Parameter ◽  
Harmonic Balance Method ◽  
Variable Stiffness ◽  
Ambient Vibration ◽  
Robotic Drilling

Vibrations in the aircraft assembly building will affect the precision of the robotic drilling system. A variable stiffness and damping semiactive vibration control mechanism with quasi-zero stiffness characteristics is developed. The quasi-zero stiffness of the mechanism is realized by the parallel connection of four vertically arranged bearing springs and two symmetrical horizontally arranged negative stiffness elements. Firstly, the quasi-zero stiffness parameters of the mechanism at the static equilibrium position are obtained through analysis. Secondly, the harmonic balance method is used to deal with the differential equations of motion. The effects of every parameter on the displacement transmissibility are analyzed, and the variable parameter control strategies are proposed. Finally, the system responses of the passive and semiactive vibration isolation mechanisms to the segmental variable frequency excitations are compared through virtual prototype experiments. The results show that the frequency range of vibration isolation is widened, and the stability of the vibration control system is effectively improved without resonance through the semiactive vibration control method. It is of innovative significance for ambient vibration control in robotic drilling systems.

scholarly journals Design of a Variable-Stiffness Compliant Skin for a Morphing Leading Edge

2021 ◽  
Vol 11 (7) ◽  
pp. 3165
Author(s):  
Zhigang Wang ◽  
Yu Yang
Keyword(s):  
Composite Laminate ◽  
Large Scale ◽  
Design Method ◽  
Leading Edge ◽  
Variable Stiffness ◽  
Manufacturing Constraints ◽  
Aircraft Wing ◽  
Noise Abatement ◽  
Civil Aircraft ◽  
Final Profile

A seamless and smooth morphing leading edge has remarkable potential for noise abatement and drag reduction of civil aircraft. Variable-stiffness compliant skin based on tailored composite laminate is a concept with great potential for morphing leading edge, but the currently proposed methods have difficulty in taking the manufacturing constraints or layup sequence into account during the optimization process. This paper proposes an innovative two-step design method for a variable-stiffness compliant skin of a morphing leading edge, which includes layup optimization and layup adjustment. The combination of these two steps can not only improve the deformation accuracy of the final profile of the compliant skin but also easily and effectively determine the layup sequence of the composite layup. With the design framework, an optimization model is created for a variable-stiffness compliant skin, and an adjustment method for its layups is presented. Finally, the deformed profiles between the directly optimized layups and the adjusted ones are compared to verify its morphing ability and accuracy. The final results demonstrate that the obtained deforming ability and accuracy are suitable for a large-scale aircraft wing.

scholarly journals Higher order Hamiltonian Monte Carlo sampling for cosmological large-scale structure analysis

2021 ◽  
Vol 502 (3) ◽  
pp. 3976-3992
Author(s):  
Mónica Hernández-Sánchez ◽  
Francisco-Shu Kitaura ◽  
Metin Ata ◽  
Claudio Dalla Vecchia
Keyword(s):  
Fourth Order ◽  
Large Scale ◽  
Equations Of Motion ◽  
Large Scale Structure ◽  
Real Space ◽  
Higher Order ◽  
Second Order ◽  
Scale Structure ◽  
Integration Schemes ◽  
Reconstruction Methods

ABSTRACT We investigate higher order symplectic integration strategies within Bayesian cosmic density field reconstruction methods. In particular, we study the fourth-order discretization of Hamiltonian equations of motion (EoM). This is achieved by recursively applying the basic second-order leap-frog scheme (considering the single evaluation of the EoM) in a combination of even numbers of forward time integration steps with a single intermediate backward step. This largely reduces the number of evaluations and random gradient computations, as required in the usual second-order case for high-dimensional cases. We restrict this study to the lognormal-Poisson model, applied to a full volume halo catalogue in real space on a cubical mesh of 1250 h−1 Mpc side and 2563 cells. Hence, we neglect selection effects, redshift space distortions, and displacements. We note that those observational and cosmic evolution effects can be accounted for in subsequent Gibbs-sampling steps within the COSMIC BIRTH algorithm. We find that going from the usual second to fourth order in the leap-frog scheme shortens the burn-in phase by a factor of at least ∼30. This implies that 75–90 independent samples are obtained while the fastest second-order method converges. After convergence, the correlation lengths indicate an improvement factor of about 3.0 fewer gradient computations for meshes of 2563 cells. In the considered cosmological scenario, the traditional leap-frog scheme turns out to outperform higher order integration schemes only when considering lower dimensional problems, e.g. meshes with 643 cells. This gain in computational efficiency can help to go towards a full Bayesian analysis of the cosmological large-scale structure for upcoming galaxy surveys.

scholarly journals Mean-Field Models for EEG/MEG: From Oscillations to Waves

2021 ◽  
Author(s):  
Áine Byrne ◽  
James Ross ◽  
Rachel Nicks ◽  
Stephen Coombes
Keyword(s):  
Gap Junction ◽  
Large Scale ◽  
Mean Field ◽  
Coarse Grained ◽  
Neural Mass Model ◽  
Neuron Network ◽  
Mass Model ◽  
Mean Field Model ◽  
Neural Mass ◽  
The Rich

AbstractNeural mass models have been used since the 1970s to model the coarse-grained activity of large populations of neurons. They have proven especially fruitful for understanding brain rhythms. However, although motivated by neurobiological considerations they are phenomenological in nature, and cannot hope to recreate some of the rich repertoire of responses seen in real neuronal tissue. Here we consider a simple spiking neuron network model that has recently been shown to admit an exact mean-field description for both synaptic and gap-junction interactions. The mean-field model takes a similar form to a standard neural mass model, with an additional dynamical equation to describe the evolution of within-population synchrony. As well as reviewing the origins of this next generation mass model we discuss its extension to describe an idealised spatially extended planar cortex. To emphasise the usefulness of this model for EEG/MEG modelling we show how it can be used to uncover the role of local gap-junction coupling in shaping large scale synaptic waves.

scholarly journals Experimental Research on Bond Behaviour of Fabric Reinforced Cementitious Matrix Composites for Retrofitting Masonry Walls

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Fayu Wang ◽  
Nicholas Kyriakides ◽  
Christis Chrysostomou ◽  
Eleftherios Eleftheriou ◽  
Renos Votsis ◽  
...  
Keyword(s):  
Large Scale ◽  
Tensile Tests ◽  
Seismic Resistance ◽  
Matrix Composites ◽  
Bond Behaviour ◽  
Cementitious Matrix ◽  
The Matrix ◽  
Rc Frame Buildings ◽  
Direct Tensile ◽  
Fabric Reinforced Cementitious Matrix

AbstractFabric reinforced cementitious matrix (FRCM) composites, also known as textile reinforced mortars (TRM), an inorganic matrix constituting fibre fabrics and cement-based mortar, are becoming a widely used composite material in Europe for upgrading the seismic resistance of existing reinforced concrete (RC) frame buildings. One way of providing seismic resistance upgrading is through the application of the proposed FRCM system on existing masonry infill walls to increase their stiffness and integrity. To examine the effectiveness of this application, the bond characteristics achieved between (a) the matrix and the masonry substrate and (b) the fabric and the matrix need to be determined. A series of experiments including 23 material performance tests, 15 direct tensile tests of dry fabric and composites, and 30 shear bond tests between the matrix and brick masonry, were carried out to investigate the fabric-to-matrix and matrix-to-substrate bond behaviour. In addition, different arrangements of extruded polystyrene (XPS) plates were applied to the FRCM to test the shear bond capacity of this insulation system when used on a large-scale wall.

scholarly journals SPARC Data Structure: Rationale and Design of a FAIR Standard for Biomedical Research Data

2021 ◽  
Author(s):  
Anita Bandrowski ◽  
Jeffrey S. Grethe ◽  
Anna Pilko ◽  
Tom Gillespie ◽  
Gabi Pine ◽  
...  
Keyword(s):  
Data Structure ◽  
Biomedical Research ◽  
Large Scale ◽  
Open Data ◽  
Cell Types ◽  
Research Data ◽  
Imaging Data ◽  
Organ Specific ◽  
The Rich ◽  
Automated Tools

AbstractThe NIH Common Fund’s Stimulating Peripheral Activity to Relieve Conditions (SPARC) initiative is a large-scale program that seeks to accelerate the development of therapeutic devices that modulate electrical activity in nerves to improve organ function. Integral to the SPARC program are the rich anatomical and functional datasets produced by investigators across the SPARC consortium that provide key details about organ-specific circuitry, including structural and functional connectivity, mapping of cell types and molecular profiling. These datasets are provided to the research community through an open data platform, the SPARC Portal. To ensure SPARC datasets are Findable, Accessible, Interoperable and Reusable (FAIR), they are all submitted to the SPARC portal following a standard scheme established by the SPARC Curation Team, called the SPARC Data Structure (SDS). Inspired by the Brain Imaging Data Structure (BIDS), the SDS has been designed to capture the large variety of data generated by SPARC investigators who are coming from all fields of biomedical research. Here we present the rationale and design of the SDS, including a description of the SPARC curation process and the automated tools for complying with the SDS, including the SDS validator and Software to Organize Data Automatically (SODA) for SPARC. The objective is to provide detailed guidelines for anyone desiring to comply with the SDS. Since the SDS are suitable for any type of biomedical research data, it can be adopted by any group desiring to follow the FAIR data principles for managing their data, even outside of the SPARC consortium. Finally, this manuscript provides a foundational framework that can be used by any organization desiring to either adapt the SDS to suit the specific needs of their data or simply desiring to design their own FAIR data sharing scheme from scratch.

scholarly journals An Analytical Prediction Model of Balanced and Unbalanced Faults in Doubly-Fed Induction Machines

2021 ◽  
Author(s):  
Frederic Maurer ◽  
Trond Leiv Toftevaag ◽  
Jonas Kristiansen Nøland
Keyword(s):  
Large Scale ◽  
Induction Machine ◽  
Design Stage ◽  
Analytical Prediction ◽  
Two Phase ◽  
Mechanical Constraints ◽  
Analytic Expressions ◽  
Doubly Fed Induction Machine ◽  
Simulation And Experiment ◽  
Doubly Fed

This paper presents the exact transient solution to the unbalanced and balanced faults in the doubly-fed induction machine (DFIM). Stator currents, rotor currents, and stator fluxes have been validated using simulation and experiment. The work is meant to strengthen and fasten the predictability of large DFIMs in the design stage to comply with mechanical constraints or grid fault issues. Moreover, the analytical approach reduces the computational costs of large-scale stability studies and is especially suited to the initial phase where a plethora design computations must be carried out for the DFIM before it is checked for its transient interaction with the power system. The possibility to dynamically estimate DFIM performance is simplified by original equations derived from first principles. First, a case study of a large 265.50 MVA DFIM is used to verify the proposed "large machine approximation" using simulation, achieving an exact match. Then, laboratory measurements were conducted on a 10.96 kVA and a 1.94 kVA DFIM to validate the transient current peaks predicted in the proposed analytic expressions for two-phase and three-phase faults, respectively.

Sign in / Sign up

Export Citation Format

Share Document