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基于子区域的结构拓扑优化并行策略

Acta Mechanica Sinica 2023年第9期39卷 114-125页

作者：赵子龙荣毅燕翌冯西桥谢亿民 Institute of Solid Mechanics School of Aeronautic Science and EngineeringBeihang UniversityBeijing 100191China Centre for Innovative Structures and Materials School of EngineeringRMIT UniversityMelbourne 300lAustralia Department of Engineering Mechanics MIIT Key Laboratory of Dynamics and Control of Complex SystemsNorthwestern Polytechnical UniversityXi'an710072China Institute of Biomechanics and Medical Engineering Department of Engineering MechanicsTsinghua UniversityBejing 100084China

结构拓扑优化在过去的三十年里经历了巨大的发展,充分利用高性能计算资源有助于拓宽拓扑优化在大规模设计问题中的应用。本文提出了一种针对一般三维拓扑优化的基于子区域的并行策略。通过子区域划分、矩阵运算、引入单元硬杀算法,优化... 详细信息

结构拓扑优化在过去的三十年里经历了巨大的发展,充分利用高性能计算资源有助于拓宽拓扑优化在大规模设计问题中的应用。本文提出了一种针对一般三维拓扑优化的基于子区域的并行策略。通过子区域划分、矩阵运算、引入单元硬杀算法,优化过程得以显著提速.将该策略整合进高效、简洁的Python代码;该代码可适用于任意形状的设计域.附录一中给出的完整代码,易于扩展,扩展后可解决多类优化问题.通过求解四个柔度最小化问题展示了该策略的高效性.本研究在机械工程、先进制造,以及建筑设计等领域有潜在的应用价值.

关键词：并行策略高性能计算子区域划分最小化问题结构拓扑优化 Python 设计域建筑设计

Symplectic Stiffness Method for the Buckling Analysis of Hierarchical and Chiral Cellular Honeycomb Structures

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SSRN 2023年

作者： Jin, Mingzhu Hou, Xiuhui Zhao, Wenhao Deng, Zichen School of Aeronautics Northwestern Polytechnical University Xi’an710072 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi’an710072 China School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi’an710072 China

Structure-function-material integration design based on the buckling instability of flexible cellular structures has attracted much attention. According to the reversible and repeatable characteristics of buckling deformation, phonon bandgap switches, the autonomous drive of soft robots, programmable logic controllers, and reusable spacecraft landing buffer devices can be designed. Based on the Hamiltonian variational principle and symplectic eigen expansion, a theoretical analysis model of the symplectic stiffness method is established, and analytical expressions for the stiffness of several typical buckling modes of elastically supported beams are obtained. The analytical closed-form expressions for the macroscopic buckling strength of honeycombs are obtained according to the bending moment equilibrium equation. The buckling modes of regular hexagonal, hierarchical hexagonal, and tri-chiral honeycombs are obtained by numerical simulation and experimental verification, and some novel higher-order modes are observed. Uniaxial compression experiments reveal that these higher-order buckling modes can be triggered by adjusting the geometric parameters of the unit cells. The high agreement between experimental, numerical, and existing literature results for the failure surfaces of cellular structures verifies the effectiveness of the proposed symplectic stiffness method. In a word, the buckling modes can be designed to meet different functional requirements by changing the initial configuration of flexible cellular structures. This provides a new idea and theoretical guidance for the development of metamaterials and structures with tailored properties. © 2023, The Authors. All rights reserved.

关键词： Stiffness

Origami-Inspired Metamaterial with Cpmpression-Twist Coupling Effect For Low-Frequency Vibration Isolation

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SSRN 2023年

作者： Liu, Xiangbing Zhang, Kai Shi, Haizhou Hong, Fang Liu, Hong Deng, Zichen School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi’an710072 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi’an710072 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian116024 China

Through unique folding methods and material selection, origami structures enable optimum structural design within a restricted space and provide strong force support. In aerospace engineering, origami-inspired structures are used in designing satellites, probes and other space devices for lightweight, compact and adjustable design requirements. A compression-twist coupled metamaterial inspired by Kresling origami structure consisting of beams and plates is presented in this study, and the vibration response of the structure is investigated. The bandgaps of the structure along longitudinal and transverse directions are studied separately due to the application of the polarization factor. The vibrational modes of the structure are further investigated to elucidate the mechanism of bandgap generation. Parametric studies make the optimal design of bandgap in graded structures possible. Finally, experiments are carried out to verify the correctness of the structural dynamic response. This research provides a new perspective on the design of origami-inspired metamaterial structures in terms of dynamics control and bandgap tuning. © 2023, The Authors. All rights reserved.

关键词： Energy gap

Explosive synchronization in multiplex neuron-glial networks

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arXiv

arXiv 2023年

作者： Laptyeva, Tetyana Jalan, Sarika Ivanchenko, Mikhail Department of Control Theory and Systems Dynamics Lobachevsky State University of Nizhny Novgorod Nizhny Novgorod Russia Complex Systems Lab Department of Physics Indian Institute of Technology Indore Indore Simrol452020 India Department of Applied Mathematics Laboratory of Systems Medicine of Healthy Aging Lobachevsky State University of Nizhny Novgorod Nizhny Novgorod Russia

Explosive synchronization refers to an abrupt (first order) transition to non-zero phase order parameter in oscillatory networks, underpinned by the bistability of synchronous and asynchronous states. Growing evidence suggests that this phenomenon might be no less general then the celebrated Kuramoto scenario that belongs to the second order universality class. Importantly, the recent examples demonstrate that explosive synchronization can occur for certain network topologies and coupling types, like the global higher-order coupling, without specific requirements on the individial oscillator dynamics or dynamics-network correlations. Here we demonstrate a rich picture of explosive synchronization and desynchronization transitions in multiplex networks, where it is sufficient to have a single random sparsly connected layer with higher-order coupling terms (and not necessarily in the synchronization regime on its own), the other layer being a regular lattice without own phase transitions at all. Moreover, explosive synchronization emerges even when the random layer has only low-order pairwise coupling, althoug the hysteresis interval becomes narrow and explosive desynchronization is no longer observed. The relevance to the normal and pathological dynamics of neural-glial networks is pointed out. © 2023, CC BY.

关键词： Synchronization

A Meta-Design of Hollow-Square-Frustum-Core Sandwich Structures for Improved Compression and Vibration Isolation Properties

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SSRN 2024年

作者： Zhang, Kai Ding, Bin Shi, Haizhou Hong, Fang Gu, Xudong Deng, Zichen School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi’an710072 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi’an710072 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian116024 China

Metamaterials can satisfy the demand for lightweight and multifunctional structures. In this study, we propose a double hollow-square-frustum-core sandwich meta-structure (meta-DHSFCSS) for vibration isolation. The out-of-plane compressive performance of the sandwich meta-structure specimen is experimentally and numerically studied. The bandgap in the band structure for out-of-plane vibration of the meta-DHSFCSS is numerically computed and verified by the frequency-domain and time-domain responses and vibration test. Parameter study is performed on the meta-DHSFCSS to investigate the effects on the structural compressive performance and vibration isolation property. The maximum load-mass ratio exceeds 283 N/g and the maximum SEA reaches 2000 kJ/kg. These two indexes are dramatically better than those of certain previous studies. The meta-DHSFCSS has a wide bandgap for vibration isolation. Gradient design and waveguide design are introduced to the meta-DHSFCSS supercell. Its vibration isolation property is improved. The locational and directional transmission of the elastic wave can be achieved by the rainbow trapping effect of gradient meta-DHSFCSS and the waveguides with different transmission routes. These demonstrate the great application of the meta-DHSFCSS in elastic wave manipulation. © 2024, The Authors. All rights reserved.

关键词： Metamaterials

Discernibility of topological variations for networked LTI systems based on observed output trajectories

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arXiv

arXiv 2022年

作者： Hao, Yuqing Wang, Qingyun Duan, Zhisheng Chen, Guanrong Department of Dynamics and Control Beihang University Beijing100191 China State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China Department of Electronic Engineering City University of Hong Kong Hong Kong

In this paper, the possibility of detecting topological variations by observing output trajectories from networked linear time-invariant systems is investigated, where the network topology can be general, but the nodes have identical higher-dimensional dynamics. A necessary and sufficient condition on the discernibility of topological variations is derived, in terms of the eigenspaces of the original and the modified network configuarations. By taking the specific network structures into consideration, some lower-dimensional conditions are derived, which reveal how the network topologies, sensor locations, node-system dynamics and output, as well as inner interactions altogether affect the discernibility. Furthermore, the output discernibility of topological changes for networked multi-agent systems is revisited, showing that some criterion reported in the literature does not hold. Consequently, a modified necessary and sufficient condition is established. The effectiveness of the results is demonstrated through several examples. © 2022, CC BY-NC-ND.

关键词： Network topology

Batch-to-Batch Optimization with Model Adaptation Leveraging Gaussian Processes: The Case of Optogenetically Assisted Microbial Consortia

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Batch-to-Batch Optimization with Model Adaptation Leveraging...

International Conference on control, Automation and systems ( ICCAS)

作者： Sebastián Espinel-Ríos Rudolph Kok Steffen Klamt José L. Avalos Rolf Findeisen Analysis and Redesign of Biological Networks Max Planck Institute for Dynamics of Complex Technical Systems Magdeburg Germany Department of Chemical and Biological Engineering Princeton University Princeton United States Institute for Automation Engineering Otto von Guericke University Magdeburg Magdeburg Germany Control and Cyber-Physical Systems Laboratory TU Darmstadt Germany

Microbial consortia are promising biotechnological production systems with the potential to divide complex metabolic pathways into smaller submodules, as well as make products and consume substrates that monocultures cannot. Maintaining optimal cell population levels and preventing mono culture formation challenge bioproduction by microbial consortia. Optogenetics allows for regulating the expression of key growth-regulatory genes through light to modulate cell population levels. Model-based dynamic optimization can determine optimal light trajectories and inoculum sizes that maximize product synthesis while satisfying system constraints, e.g., safety, economic, or technical aspects. Further-more, closed-loop dynamic optimization can address system uncertainty to a certain extent; however, its implementation is challenging due to limited online sensors. Alternatively, here we propose to perform open-loop optimization with batch-to-batch model adaptation based on Gaussian processes for maximizing bioproduction by optogenetically assisted consortia. The proposed approach enables knowledge transfer from existing to new models, improving predictability and optimization performance in each batch while avoiding costly and time-consuming modeling experiments. Compared to closed-loop optimization, this strategy is easier to implement as it does not rely on online monitoring, contributing to the state of the art in optimizing bioproduction by microbial consortia. We outline the applicability of the approach using simulation experiments of an optogenetically assisted consortium for the biosynthesis of the flavonoid naringenin, considering both parameter and model structure uncertainty.

关键词：

Evolutionary dynamics on graphs: Efficient method for weak selection

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Physical Review E 2009年第4期79卷 046707-046707页

作者： Feng Fu Long Wang Martin A. Nowak Christoph Hauert Program for Evolutionary Dynamics Harvard University Cambridge Massachusetts 02138 USA Center for Systems and Control State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing 100871 China Department of Organismic and Evolutionary Biology and Department of Mathematics Harvard University Cambridge Massachusetts 02138 USA Department of Mathematics University of British Columbia Vancouver British Columbia Canada V6T 1Z2

Investigating the evolutionary dynamics of game theoretical interactions in populations where individuals are arranged on a graph can be challenging in terms of computation time. Here, we propose an efficient method to study any type of game on arbitrary graph structures for weak selection. In this limit, evolutionary game dynamics represents a first-order correction to neutral evolution. Spatial correlations can be empirically determined under neutral evolution and provide the basis for formulating the game dynamics as a discrete Markov process by incorporating a detailed description of the microscopic dynamics based on the neutral correlations. This framework is then applied to one of the most intriguing questions in evolutionary biology: the evolution of cooperation. We demonstrate that the degree heterogeneity of a graph impedes cooperation and that the success of tit for tat depends not only on the number of rounds but also on the degree of the graph. Moreover, considering the mutation-selection equilibrium shows that the symmetry of the stationary distribution of states under weak selection is skewed in favor of defectors for larger selection strengths. In particular, degree heterogeneity—a prominent feature of scale-free networks—generally results in a more pronounced increase in the critical benefit-to-cost ratio required for evolution to favor cooperation as compared to regular graphs. This conclusion is corroborated by an analysis of the effects of population structures on the fixation probabilities of strategies in general 2×2 games for different types of graphs. Computer simulations confirm the predictive power of our method and illustrate the improved accuracy as compared to previous studies.

关键词： dynamics

Thermoelastic Modeling and Transient Responses with Piezoelectric and Size Effects

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SSRN 2024年

作者： Li, Si-Yang Wu, Hua Yu, Ya-Jun School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi’an710072 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi’an710072 China School of Aeronautics Northwestern Polytechnical University Xi’an710072 China National Key Laboratory of Strength and Structural Integrity Xi’an710072 China

Generalized piezoelectric thermoelastic models play significantly important role in multi-field coupling analysis, especially in extreme environments, of nanosensors, nanogenerators and superconductivity. In this work, generalized thermoelastic theory is firstly proposed by considering higher-order thermal lagging and size effect. Then, unified generalized piezoelectric thermoelastic coupling model is obtained by further combining piezoelectric effect. Transient piezoelectric thermoelastic responses of piezoelectric materials under thermal shock are investigated. Numerical results are obtained from analytical solution in Laplace domain by adopting numerical inverse Laplace transform. The obtained results are graphically illustrated, from which the effects of lagging effect and size effect are clarified. This work provides theoretical model and numerical method to predict transient thermoelastic behaviors of piezoelectric materials across different time and space scales. © 2024, The Authors. All rights reserved.

关键词： Transient analysis