Journal of Computational and Nonlinear Dynamics最新文献_第3页

Introduction of Local Resonators to a Nonlinear Metamaterial with Topological Features 为具有拓扑特征的非线性超材料引入局部谐振器

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-02-12 DOI: 10.1115/1.4064726

Joshua LeGrande, A. Malla, M. Bukhari, Oumar Barry

{"title":"Introduction of Local Resonators to a Nonlinear Metamaterial with Topological Features","authors":"Joshua LeGrande, A. Malla, M. Bukhari, Oumar Barry","doi":"10.1115/1.4064726","DOIUrl":"https://doi.org/10.1115/1.4064726","url":null,"abstract":"\u0000 Recent work in nonlinear topological metamaterials has revealed many useful properties such as amplitude dependent localized vibration modes and nonreciprocal wave propagation. However, thus far, there have not been any studies to include the use of local resonators in these systems. This work seeks to fill that gap through investigating a nonlinear quasiperiodic metamaterial with periodic local resonator attachments. We model a 1-dimensional metamaterial lattice as a spring-mass chain with coupled local resonators. Quasiperiodic modulation in the nonlinear connecting springs is utilized to achieve topological features. For comparison, a similar system without local resonators is also modeled. Both analytical and numerical methods are used to study this system. The dispersion relation of the infinite chain of the proposed system is determined analytically through the perturbation method of multiple scales. This analytical solution is compared to the finite chain response, estimated using the method of harmonic balance and solved numerically. The resulting band structures and mode shapes are used to study the effects of quasiperiodic parameters and excitation amplitude on the system behavior both with and without the presence of local resonators. Specifically, the impact of local resonators on topological features such as edge modes is established, demonstrating the appearance of a trivial bandgap and multiple localized edge states for both main cells and local resonators. These results highlight the interplay between local resonance and nonlinearity in a topological metamaterial demonstrating for the first time the presence of an amplitude invariant bandgap alongside amplitude dependent topological bandgaps.","PeriodicalId":506262,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"61 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139844300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Long-Term Prediction of Large-Scale and Sporadic COVID-19 Epidemics Induced by the Original Strain in China Based On the Improved Non-Autonomous Delayed SIRD and SIR Models 基于改进的非自主延迟 SIRD 和 SIR 模型对中国原始菌株诱发的大规模和零星 COVID-19 流行病进行长期预测

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-02-12 DOI: 10.1115/1.4064720

Xin Xie, Lijun Pei

{"title":"Long-Term Prediction of Large-Scale and Sporadic COVID-19 Epidemics Induced by the Original Strain in China Based On the Improved Non-Autonomous Delayed SIRD and SIR Models","authors":"Xin Xie, Lijun Pei","doi":"10.1115/1.4064720","DOIUrl":"https://doi.org/10.1115/1.4064720","url":null,"abstract":"\u0000 The COVID-19 virus emerged suddenly in early 2020 and spread rapidly, causing a significant impact on national health. To achieve our goal, we introduce a time-delay factor based on the traditional SIR/SIRD model and perform a sliding average on the data collected from the official website during the data preprocessing stage. The results of this study are in very good agreement with the actual evolution of COVID-19, and the prediction accuracy can all be controlled within 3%. From our model parameter perspective, under strict isolation policies, the transmission rate of COVID-19 in China is relatively low and still significantly reduced, indicating that government intervention has had a positive effect on epidemic prevention in the country. Besides, our model is also successfully applied to predict the outbreaks caused by the SARS virus in 2003 and the COVID-19 outbreak induced by the Omicron virus in 2022, demonstrating its wide application and effectiveness. This work facilitates timely measures and adjustment of medical resources in various regions, ultimately helping to reduce economic and social losses.","PeriodicalId":506262,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"29 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139784850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Approximate Analysis of Higher-Order Frequencies of Nonlinear Vibrations of a Cantilever Beam with the Extended Galerkin Method 用扩展伽勒金方法近似分析悬臂梁非线性振动的高阶频率

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-02-12 DOI: 10.1115/1.4064724

Baochen Meng, Chencheng Lian, Ji Wang, Huimin Jing, Rongxing Wu, Ji Lin, Isaac Elishakoff

引用次数: 0

Influence of Unbalance and Differential Pressure On the Stability of Vertical Rotor-seal System 不平衡和压差对垂直转子密封系统稳定性的影响

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-02-12 DOI: 10.1115/1.4064725

S. Roy Kimura, Tsuyoshi Inoue, Hiroo Taura, Akira Heya

{"title":"Influence of Unbalance and Differential Pressure On the Stability of Vertical Rotor-seal System","authors":"S. Roy Kimura, Tsuyoshi Inoue, Hiroo Taura, Akira Heya","doi":"10.1115/1.4064725","DOIUrl":"https://doi.org/10.1115/1.4064725","url":null,"abstract":"\u0000 The rotordynamic (RD) fluid force generated in fluid elements such as seals in turbomachinery affects the stability of turbomachinery and causes shaft vibrations. Various studies have been conducted to clarify the effects of seals on the stability of rotor systems. Many studies have investigated the rotor dynamics of horizontal shaft systems, considering the RD fluid force generated in the seals, and in these studies, the stability of horizontal shaft systems has been assessed via eigenvalue analysis using RD coefficients. However, few studies have analyzed vertical shaft systems. The dynamic behavior of vertical shafts differs significantly from that of horizontal shafts because the weight of the rotor does not act on the seal in a vertical shaft system. Vertical shaft systems are generally prone to instability because of the fluid film whirl, and the amplitude of the shaft whirl tends to be large. When the amplitude is large, the RD fluid force cannot be linearized around the equilibrium point using RD coefficients. Therefore, destabilization and stabilization phenomena that appear in vertical shaft systems cannot be predicted using eigenvalue analysis. Fluid-structure interaction (FSI) analysis that considers the interaction between the shaft vibration and the RD fluid force generated in seals is required to predict such phenomena. This study used FSI analysis to investigate the effects of unbalance and differential pressure on the stability of a vertical shaft system subjected to RD fluid force generated in the seal.","PeriodicalId":506262,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"60 47","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139844771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Chaotic Dynamics of a Duffing Oscillator Subjected to External and Nonlinear Parametric Excitations with Delayed Feedbacks 带有延迟反馈的外部和非线性参数激励下的达芬振荡器的混沌动力学

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-02-12 DOI: 10.1115/1.4064723

Aijia Ding, Sengen Hu, Liangqiang Zhou

引用次数: 0

A New Method for Solving Physical Problems with Nonlinear Phoneme within Fractional Derivatives with Singular Kernel 用奇异核分式导数解决非线性音素物理问题的新方法

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-02-12 DOI: 10.1115/1.4064719

Sondos M. Syam, Z. Siri, Sami Altoum, M. Aigo, R. Md Kasmani

引用次数: 0

Long-Term Prediction of Large-Scale and Sporadic COVID-19 Epidemics Induced by the Original Strain in China Based On the Improved Non-Autonomous Delayed SIRD and SIR Models 基于改进的非自主延迟 SIRD 和 SIR 模型对中国原始菌株诱发的大规模和零星 COVID-19 流行病进行长期预测

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-02-12 DOI: 10.1115/1.4064720

Xin Xie, Lijun Pei

{"title":"Long-Term Prediction of Large-Scale and Sporadic COVID-19 Epidemics Induced by the Original Strain in China Based On the Improved Non-Autonomous Delayed SIRD and SIR Models","authors":"Xin Xie, Lijun Pei","doi":"10.1115/1.4064720","DOIUrl":"https://doi.org/10.1115/1.4064720","url":null,"abstract":"\u0000 The COVID-19 virus emerged suddenly in early 2020 and spread rapidly, causing a significant impact on national health. To achieve our goal, we introduce a time-delay factor based on the traditional SIR/SIRD model and perform a sliding average on the data collected from the official website during the data preprocessing stage. The results of this study are in very good agreement with the actual evolution of COVID-19, and the prediction accuracy can all be controlled within 3%. From our model parameter perspective, under strict isolation policies, the transmission rate of COVID-19 in China is relatively low and still significantly reduced, indicating that government intervention has had a positive effect on epidemic prevention in the country. Besides, our model is also successfully applied to predict the outbreaks caused by the SARS virus in 2003 and the COVID-19 outbreak induced by the Omicron virus in 2022, demonstrating its wide application and effectiveness. This work facilitates timely measures and adjustment of medical resources in various regions, ultimately helping to reduce economic and social losses.","PeriodicalId":506262,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"56 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139844726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Presence of Chaos in a Viscoelastic Harmonically Forced Von Mises Truss 粘弹性谐波强制冯米塞斯桁架中的混沌现象

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-01-25 DOI: 10.1115/1.4064554

Pritam Ghoshal, James Gibert, Anil K. Bajaj

{"title":"The Presence of Chaos in a Viscoelastic Harmonically Forced Von Mises Truss","authors":"Pritam Ghoshal, James Gibert, Anil K. Bajaj","doi":"10.1115/1.4064554","DOIUrl":"https://doi.org/10.1115/1.4064554","url":null,"abstract":"\u0000 This work investigates how viscoelasticity affects the dynamic behavior of a lumped-parameter model of a bistable von Mises truss. The system is controlled by a linear first-order equation and a second-order nonlinear Duffing equation with a quadratic nonlinearity that governs mechanical behavior. The second-order equation controls mechanical oscillations, while the linear first-order equation controls viscoelastic force evolution. Combined, the two equations form a third-order jerk equation that controls system dynamics. Viscoelasticity adds time scales and degrees of freedom to material behavior, distinguishing it from viscosity-only systems. Due to harmonic excitation, the system exhibits varied dynamic responses from periodic to quasiperiodic to chaotic. We explore the dynamics of a harmonically forced von Mises truss with viscous damping to address this purpose. We demonstrate this system's rich dynamic behavior due to driving amplitude changes. This helps explain viscoelastic system behavior. A viscoelastic unit replaces the viscous damper, and we show that, although viscous damping merely changes how fast the trajectory decays to an attractor, viscoelasticity modifies both the energy landscape and the rate of decay. In a conventional linear solid model, three viscoelastic parameters control the system's behavior instead of one, as in pure viscous damping. This adds degrees of freedom that affect system dynamics. We present the parameter space for chaotic behavior and the shift from regular to irregular motion. Finally, Melnikov's criteria identify the regular-chaotic threshold. The system's viscous and elastic components affect the chaotic threshold amplitude.","PeriodicalId":506262,"journal":{"name":"Journal of Computational and Nonlinear Dynamics","volume":"56 31","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139598736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Solutions of Time-Space Fractional PDEs Using Picard's Iterative Method 使用皮卡尔迭代法求解时空分式 PDEs

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-01-25 DOI: 10.1115/1.4064553

Manoj Kumar, Aman Jhinga, J. T. Majithia

引用次数: 0

Open-Loop Centering of a Point Mass on a Horizontally Vibrating Frictional Table 水平振动摩擦台上点质量的开环定心

Journal of Computational and Nonlinear Dynamics Pub Date : 2024-01-25 DOI: 10.1115/1.4064552

Dheeraj Varma Manthena, C. P. Vyasarayani, Anindya Chatterjee

引用次数: 0