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Linear stability analysis of the viscoelastic Navier–Stokes–Voigt fluid model through Brinkman porous media: Modal and non-modal approaches 通过布林克曼多孔介质的粘弹性 Navier-Stokes-Voigt 流体模型的线性稳定性分析:模态和非模态方法
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-30 DOI: 10.1016/j.ijnonlinmec.2024.104885

The linear stability analysis of a viscoelastic Navier-Stokes-Voigt fluid flow, or the Kelvin-Voigt fluid of zero order in a Brinkman porous medium, is investigated using both modal and non-modal analysis. The numerical solution is obtained using the Chebyshev collocation method. The combined effects of the medium's porosity, represented by the porous parameter, the fluid viscosity, represented by the ratio of effective viscosity to fluid viscosity, and the fluid elasticity, represented by the Kelvin-Voigt parameter are investigated using both modal and non-modal analysis. The modal analysis describes the long-term behavior of the system, obtained through plotting the eigenspectrum, eigenfunctions, growth rate curves, neutral stability curves, and streamline plots, along with accurate values of critical triplets. In non-modal analysis, the pseudospectrum of the Orr-Sommerfeld operator, transient energy growth curves, and regions of stability, instability, and potential instability are depicted. The results obtained from modal analysis indicate that the porous parameter, Kelvin-Voigt parameter, and the ratio of effective viscosity to fluid viscosity act as stabilizing agents. However, using non-modal analysis, it is observed that while the porous parameter and the ratio of effective viscosity to fluid viscosity act as stabilizing agents, the Kelvin-Voigt parameter acts as a destabilizing agent over shorter periods.

通过模态和非模态分析,研究了布林克曼多孔介质中粘弹性纳维-斯托克斯-沃伊特流体或零阶开尔文-沃伊特流体流动的线性稳定性分析。数值求解采用切比雪夫配位法。采用模态和非模态分析方法研究了以多孔参数表示的介质孔隙率、以有效粘度与流体粘度之比表示的流体粘度以及以开尔文-沃依格参数表示的流体弹性的综合影响。模态分析描述了系统的长期行为,通过绘制特征谱、特征函数、增长率曲线、中性稳定性曲线和流线图,以及临界三元组的精确值获得。在非模态分析中,描绘了 Orr-Sommerfeld 算子的伪谱、瞬态能量增长曲线以及稳定、不稳定和潜在不稳定区域。模态分析得出的结果表明,多孔参数、开尔文-沃伊特参数以及有效粘度与流体粘度之比起到了稳定作用。然而,通过非模态分析可以发现,虽然多孔参数和有效粘度与流体粘度之比起到了稳定作用,但开尔文-沃依格参数在较短时间内起到了破坏稳定的作用。
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引用次数: 0
Investigation on dynamic behaviors of the cage in cylindrical roller bearings based on nonlinear dynamic model with lubrication and cage whirling 基于润滑和保持架旋转的非线性动态模型的圆柱滚子轴承保持架动态行为研究
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-30 DOI: 10.1016/j.ijnonlinmec.2024.104887

The dynamic characteristics of the cages of cylindrical roller bearings (CRBs) significantly impact the service life of the bearings. This paper considers the lubrication between the roller and cage and the effect of cage whirling and establishes an accurate CRBs nonlinear dynamic model. On this basis, the correlation between the stability of the cage centroid trajectory, cage sliding characteristics, and bearing operating parameters is elaborated on. In addition, the influence of structural parameters, such as the number of rollers and pocket clearance, on the dynamic characteristics of the bearing system is also investigated. The results indicate that in the design stage of CRBs, it is essential to ensure a reasonable number of rollers and a smaller cage clearance ratio to reduce the slippage rate and enhance the stability of the bearing cage. Furthermore, during the usage stage of CRBs, changes in load or rotational speed operating parameters can lead to cage whirling. However, the stability of the cage whirling under the former condition is higher than that under the latter. Therefore, it is necessary to fully consider the reasonable rotational speed and load conditions to prevent premature damage to the cage.

圆柱滚子轴承(CRB)保持架的动态特性对轴承的使用寿命有很大影响。本文考虑了滚子和保持架之间的润滑以及保持架旋转的影响,建立了精确的 CRB 非线性动态模型。在此基础上,阐述了保持架中心轨迹稳定性、保持架滑动特性和轴承运行参数之间的相关性。此外,还研究了结构参数(如滚子数量和袋间隙)对轴承系统动态特性的影响。结果表明,在 CRB 的设计阶段,必须确保合理的滚子数量和较小的保持架间隙比,以降低滑移率并增强轴承保持架的稳定性。此外,在 CRB 的使用阶段,载荷或转速运行参数的变化会导致保持架旋转。然而,前一种情况下保持架旋转的稳定性要高于后一种情况。因此,有必要充分考虑合理的转速和负载条件,以防止保持架过早损坏。
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引用次数: 0
Death transitions in attractive–repulsive coupled oscillators with higher-order interactions 具有高阶相互作用的吸引力-反冲力耦合振荡器中的死亡转变
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-30 DOI: 10.1016/j.ijnonlinmec.2024.104882

The first-order phase transition from oscillation to steady state, known as explosive death (ED), is prevalent in various dynamical models. However, previous studies on ED have predominantly focused on interactions between pairs of elements. In this work, we investigate how death transitions occur when both pairwise and three-body interactions are present in an extended Van der Pol oscillator network with attractive–repulsive coupling. By examining both global and non-local interaction mechanisms, the impact of higher-order interactions on ED and the differences in the transition process are comprehensively analyzed. Firstly, we construct a diagram of the global dynamics in the context of higher-order and first-order coupling strengths, identifying that the higher-order interactions promote the onset of ED with a contribution comparable to that of first-order interactions. Specifically, for global coupling, the theoretical backward critical curves matching the numerical results are derived through linear stability analyses, showcasing a linear correlation with a slope of -1 between the higher-order and first-order coupling strengths. Under non-local coupling, fitting the numerically obtained backward critical curves likewise yields a consistent quantitative relationship. Additionally, during the transition process of ED, we discover intriguing coexisting states in the hysteresis area under non-local coupling, including the coexistence of chimera states with coherent or incoherent oscillation, and the coexistence of chimera states with oscillation death. This is attributed to symmetry breaking induced by non-local action. These findings enhance the understanding of higher-order interactions in complex systems and provide a fresh perspective for studying multi-stability behavior in biochemical and physical systems.

从振荡到稳态的一阶相变,即爆炸性死亡(ED),在各种动力学模型中都很普遍。然而,以往对 ED 的研究主要集中在元素对之间的相互作用。在这项工作中,我们研究了当具有吸引力-反冲力耦合的扩展范德波尔振荡器网络中同时存在成对和三体相互作用时,死亡转变是如何发生的。通过研究全局和非局部相互作用机制,我们全面分析了高阶相互作用对 ED 的影响以及过渡过程的差异。首先,我们构建了高阶耦合强度和一阶耦合强度下的全局动力学图,发现高阶相互作用促进了 ED 的发生,其贡献与一阶相互作用相当。具体来说,对于全局耦合,通过线性稳定性分析得出了与数值结果相匹配的理论后向临界曲线,显示了高阶耦合强度与一阶耦合强度之间斜率为-1的线性相关。在非局部耦合条件下,拟合数值结果得到的后向临界曲线同样可以得到一致的定量关系。此外,在 ED 的转变过程中,我们还发现了非局部耦合条件下滞后区域中的一些有趣的共存状态,包括具有相干或不相干振荡的嵌合态共存,以及具有振荡死亡的嵌合态共存。这归因于非局部作用引起的对称性破缺。这些发现加深了人们对复杂系统中高阶相互作用的理解,并为研究生化和物理系统中的多稳定性行为提供了一个全新的视角。
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引用次数: 0
Influence of lubrication state transition on dynamic characteristics of deep groove ball bearing with localized defect in thermal environment 润滑状态转变对热环境中存在局部缺陷的深沟球轴承动态特性的影响
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-30 DOI: 10.1016/j.ijnonlinmec.2024.104879

The accuracy of the vibration response in a defective bearing dynamics model depends on the precise representation of the lubrication friction state between the rolling element (RE) and the raceway within the model. In this study, a fault dynamic model for outer ring defect of deep groove ball bearings (DGBBs), considering the lubrication state transition in a thermal environment, is established. This model accounts for the asperity contact effect during the lubrication state transition and integrates the lubrication-friction model for temperature changes into the dynamic model when skidding occurs. The influence of lubrication state change on the fault frequency of outer ring of DGBB in thermal environment is studied. The experimental and simulation results indicate that the lubrication state of the bearing is gradually deteriorated from elastohydrodynamic lubrication to mixed lubrication with the increase of working temperature. The transformation of the lubrication state is shown to have a significant effect on friction, resulting in the fault frequency of the outer ring increasing with temperature, which exhibits substantial deviation in the thermal environment. In the temperature range of 30 °C–150 °C, the deviation of defect frequency reaches 15.5%, which affects the accuracy of bearing fault diagnosis. This study may offer recommendations for enhancing the condition monitoring of rolling bearings under extreme working conditions.

轴承缺陷动力学模型中振动响应的准确性取决于模型中滚动体(RE)与滚道之间润滑摩擦状态的精确表达。本研究建立了深沟球轴承(DGBB)外圈缺陷的故障动力学模型,考虑了热环境下的润滑状态转换。该模型考虑了润滑状态转换过程中的非圆面接触效应,并将温度变化时的润滑-摩擦模型整合到发生打滑时的动态模型中。研究了热环境下润滑状态变化对 DGBB 外环故障频率的影响。实验和仿真结果表明,随着工作温度的升高,轴承的润滑状态由弹性流体动力润滑逐渐恶化为混合润滑。润滑状态的转变对摩擦有显著影响,导致外圈的故障频率随温度升高而增加,在热环境中表现出很大的偏差。在 30 °C-150 °C 的温度范围内,故障频率的偏差达到 15.5%,影响了轴承故障诊断的准确性。本研究可为加强极端工况下滚动轴承的状态监测提供建议。
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引用次数: 0
Nonlinear free vibration analysis of imperfect cylindrical panels with discontinuous unilateral elastic base 具有不连续单侧弹性基底的不完美圆柱面板的非线性自由振动分析
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-28 DOI: 10.1016/j.ijnonlinmec.2024.104884

In this work, the nonlinear free vibration analysis of the imperfect cylindrical panels in contact with discontinuous unilateral elastic base are conducted, evaluating the influence of the type of contact, unilateral or bilateral, and the contact area of the elastic base on the natural frequencies and nonlinear frequency-amplitude relations. For that, the structural cylindrical panel model considers the Donnell's nonlinear shallow shell theory to obtain the partial differential equilibrium equation and the compatibility and continuity equation. To represent the unilateral capability of the elastic base, a signum function is inserted in the reaction force of the elastic base to describe its dependence of the transversal displacement field of the cylindrical panel. To apply the elastic base in certain subdomain of the cylindrical panel, a Heaviside-type function is also inserted into elastic base's reaction forces. The nonlinear equilibrium equation is discretized by the Galerkin method, using a consistent transversal displacement field that it was obtained from a perturbation technique. The discretized set of equilibrium equations is employed to obtain the natural frequencies and the nonlinear frequency-amplitude relations, evaluating the influence of the unilateral contact and the contact region of the elastic base on these results. Depending on the signal of the imperfection's magnitude and the type of contact of the elastic base, the imperfect cylindrical panel can display an initial gap between the cylindrical panel and the elastic base, and this possibility is also investigated in this work. From the numerical results, it is observed that the unilateral elastic base applies less structural stiffness than the bilateral elastic base, decreasing the natural frequencies for the same imperfect cylindrical panel. The localization of the elastic base in the cylindrical panel also affects the natural frequencies, increasing or decreasing them depending on the modifications on the structural stiffness. The frequency-amplitude relations are strongly influenced by both unilateral contact of elastic base and the type of the contact consideration between the cylindrical panel and elastic base, exhibiting an intricated nonlinear behavior.

本研究对与不连续单侧弹性基座接触的不完全圆柱面板进行了非线性自由振动分析,评估了单侧或双边接触类型以及弹性基座接触面积对固有频率和非线性频率-振幅关系的影响。为此,结构圆柱面板模型考虑了 Donnell 的非线性浅壳理论,以获得偏微分平衡方程以及相容性和连续性方程。为了表示弹性基座的单边能力,在弹性基座的反作用力中插入了一个符号函数,以描述其与圆柱面板横向位移场的关系。为了在圆柱面板的某些子域中应用弹性基座,还在弹性基座的反作用力中插入了一个 Heaviside 型函数。非线性平衡方程采用 Galerkin 方法离散化,使用的是通过扰动技术获得的一致横向位移场。利用离散平衡方程组获得自然频率和非线性频率-振幅关系,并评估单侧接触和弹性基座接触区域对这些结果的影响。根据不完美程度的信号和弹性基座的接触类型,不完美的圆柱形面板和弹性基座之间可能会出现初始间隙,本研究也对这种可能性进行了研究。从数值结果可以看出,单侧弹性基座的结构刚度小于双侧弹性基座,从而降低了相同不完美圆柱面板的固有频率。弹性基座在圆柱形面板中的定位也会影响固有频率,根据对结构刚度的修改而增加或减少固有频率。频率-振幅关系受到弹性基座单侧接触以及圆柱面板与弹性基座之间接触类型的强烈影响,表现出复杂的非线性行为。
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引用次数: 0
Hysteresis and loss characteristics of metal rubber damper based on improved Preisach model 基于改进型 Preisach 模型的金属橡胶阻尼器磁滞和损耗特性
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-28 DOI: 10.1016/j.ijnonlinmec.2024.104877

In this study, a new hysteresis mechanical model of metal rubber was developed based on the magnetic flux change of metal rubber damper after cyclic loading and the subsequent static stiffness degradation This new model aims to overcome the shortcomings of the traditional high-order friction theory hysteresis model in explaining the stiffness fluctuation and temperature magnetic flux change of the shock absorber. Through the large load cyclic loading experiment of the metal rubber damper, the hysteresis characteristics of the metal rubber damper without fatigue fracture were ana-lyzed in depth. Based on the electromagnetic theory and the force and displacement constitutive relationship of the metal rubber, the Preisach mechanical hysteresis model was established. The experimental test outcomes were substituted into the model for parameter identification and the model was modified as necessary. Compared to the traditional dynamic hysteresis model based on power series and elliptic equation, the Preisach model showed higher accuracy in simulating the energy dissipation and damping ratio of the experimental data of the shock absorber. The error was controlled within 2 %. Especially in the abrupt region of the unloading curve, the nonlinear stiffness error of the Preisach model was determined to be only half of that of the traditional model. The Preisach mechanical hysteresis model deeply explores the microscopic electromagnetic characteristics of the metal rubber damper, thus revealing the internal mechanism of its hysteresis change. This model can not only accurately simulate the sudden change of the curve of the shock absorber during the unloading process, but also make the model prediction closer to the actual application scenario through the highly simulated simulation results.

本研究根据金属橡胶减震器在循环加载后的磁通量变化以及随之而来的静态刚度衰减,建立了一种新的金属橡胶滞后力学模型,旨在克服传统高阶摩擦理论滞后模型在解释减震器刚度波动和温度磁通量变化方面的不足。通过对金属橡胶减振器的大载荷循环加载实验,深入分析了金属橡胶减振器无疲劳断裂的滞后特性。基于电磁理论和金属橡胶的力与位移构成关系,建立了 Preisach 机械滞后模型。将实验测试结果代入模型进行参数识别,并对模型进行必要的修改。与基于幂级数和椭圆方程的传统动态滞后模型相比,Preisach 模型在模拟减震器实验数据的能量耗散和阻尼比方面表现出更高的精度。误差控制在 2% 以内。特别是在卸载曲线的突变区域,Preisach 模型的非线性刚度误差仅为传统模型的一半。Preisach 机械滞后模型深入探讨了金属橡胶阻尼器的微观电磁特性,从而揭示了其滞后变化的内在机理。该模型不仅能准确模拟减震器在卸载过程中曲线的突然变化,还能通过高度仿真的模拟结果使模型预测更接近实际应用场景。
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引用次数: 0
Crookedness detection of thrust ball bearing shaft washer based on nonlinear vibration responses 基于非线性振动响应的推力球轴承轴垫圈歪斜检测
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-27 DOI: 10.1016/j.ijnonlinmec.2024.104880

Bearing misalignments are common defects in machinery. One of the most important types of that is the angular misalignment of the bearing rings. In this study, crookedness specific signature related to thrust ball bearing shaft washer is investigated. For this purpose, a vertical structural thrust ball bearing test rig was considered. In the following, effects of rotational shaft speed, crookedness value and axial external force on the shaft washer crookedness signature were studied at several relative positions of sensors. It is shown that crookedness of thrust ball bearing shaft washer has specific frequency and sensor phase difference pattern in the nonlinear vibration responses. Also, the experimental results are applied to validate results of a 4-dof nonlinear dynamical system related to the shaft washer crookedness of thrust ball bearing. In the next step, by comparing input and output amplitude and also existence of flip bifurcation, it is illustrated that this system is a nonlinear dynamical experimental system. It was shown that this nonlinearity makes crooked shaft washer pattern difficult to identify. Finally, by the phase portrait of the sensor response and the relative error value of crookedness signature frequencies, it is clear that the crookedness of shaft washer creates quasi-chaotic behavior supporting crookedness signature frequencies and phase pattern as a supplement property.

轴承不对中是机械中常见的缺陷。其中最重要的一种是轴承套圈的角度不对中。本研究调查了与推力球轴承轴垫圈有关的歪斜特定特征。为此,考虑了垂直结构推力球轴承试验台。随后,在传感器的几个相对位置上研究了轴转速、弯曲度值和轴向外力对轴垫圈弯曲度特征的影响。结果表明,推力球轴承轴垫圈的弯曲度在非线性振动响应中具有特定的频率和传感器相位差模式。此外,实验结果还被用于验证与推力球轴承轴垫圈歪斜相关的 4-dof 非线性动力系统的结果。下一步,通过比较输入和输出振幅以及翻转分岔的存在,说明该系统是一个非线性动力学实验系统。结果表明,这种非线性使得歪轴垫圈模式难以识别。最后,通过传感器响应的相位肖像和歪斜特征频率的相对误差值,可以清楚地看出,轴垫圈的歪斜产生了支持歪斜特征频率和相位模式作为补充属性的准混沌行为。
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引用次数: 0
Propagation of linear and weakly nonlinear waves in Hall-magnetohydrodynamic flows 霍尔磁流体流中线性波和弱非线性波的传播
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-24 DOI: 10.1016/j.ijnonlinmec.2024.104883

We study in this paper linear and weakly nonlinear waves within the framework of a Hall-magnetohydrodynamic model. An optimal ordering, which allows the Hall effect to be seen in the leading order equations, is used to discuss the propagation of such waves; an evolution equation is obtained where the nonlinearity and Hall effect enter through the parameters that influence the wave propagation significantly. The interplay between nonlinearity and Hall effect leads to the emergence of a dispersive shock wave, which appears as the solution to the initial value problem associated with the evolution equation. The present study reveals a number of interesting flow characteristics which are not seen in the theory of ideal magnetohydrodynamics.

本文在霍尔磁流体动力学模型的框架内研究了线性波和弱非线性波。我们使用了一种最佳排序方法来讨论这种波的传播,这种方法允许在前序方程中看到霍尔效应;我们得到了一个演化方程,在这个方程中,非线性和霍尔效应通过对波的传播有重大影响的参数进入。非线性和霍尔效应之间的相互作用导致了色散冲击波的出现,它是与演化方程相关的初值问题的解。本研究揭示了许多在理想磁流体力学理论中看不到的有趣流动特征。
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引用次数: 0
Research on autocannon firing dispersion based on bond space method 基于结合空间法的自动炮射击散布研究
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-23 DOI: 10.1016/j.ijnonlinmec.2024.104876

This paper is devoted to constructing a dynamic numerical model for the firing dispersion caused by the autocannon dynamic characteristics. The buffer dynamics and projectile-barrel coupling are considered. First, the simulation of autocannon firing dispersion using commercial software usually leads to expensive computational costs. Second, autocannon dynamic design includes multiple subsystem models with nonlinearities. The conventional design method makes it difficult to describe the dynamic response of such complex systems with a unified model. To end these, a dynamic junction bond space method is proposed for analyzing muzzle vibration and firing dispersion under continuous firing loads, where the gene expression programming (GEP) method is adopted to construct the surrogate model for the buffer flow field. For the coupling analysis of the projectile and barrel, the projectile load is applied at a moving junction, which coincides with the flexible node of the barrel. By this, the dynamic numerical model for autocannon firing dispersion is established, and then the system state equation is obtained for each time step. Moreover, an autocannon standing target shooting example is presented to demonstrate the validity of the proposed method; the results show that the firing dispersion from the bond space model is consistent with the test.

本文致力于为自动火炮动态特性引起的发射散射构建动态数值模型。其中考虑了缓冲器动力学和弹丸-炮管耦合。首先,使用商业软件模拟自动榴弹炮的发射散布通常会导致昂贵的计算成本。其次,自动火炮动态设计包括多个非线性子系统模型。传统的设计方法难以用统一的模型来描述这种复杂系统的动态响应。为此,本文提出了一种动态交界键空间方法,用于分析连续发射载荷下的炮口振动和发射散布,其中采用了基因表达编程(GEP)方法来构建缓冲流场的代用模型。在弹丸和枪管的耦合分析中,弹丸载荷施加在移动交界处,该交界处与枪管的柔性节点重合。由此,建立了自动火炮发射散布的动态数值模型,并得到了每个时间步的系统状态方程。此外,为了证明所提方法的有效性,还给出了一个自动火炮立靶射击实例;结果表明,结合空间模型得出的射击离散度与测试结果一致。
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引用次数: 0
Extracting and analyzing the governing model for plastic deformation of metallic glasses 提取和分析金属玻璃塑性变形的调控模型
IF 2.8 3区 工程技术 Q2 MECHANICS Pub Date : 2024-08-22 DOI: 10.1016/j.ijnonlinmec.2024.104869

This paper first detects hidden system from plastic deformation of metallic glasses by sparse identification. The extracted model simulates four types of stress-time curves and displays the prediction of serrated events. This interpretation effectively explains various experimental phenomena of repeated yielding. Further, in terms of parametric sensitivity analysis to the model, two parameters are taken as bifurcation parameter, and the analysis of codimension-one and codimension-two bifurcation are carried out to excavate the causes of dynamic transformation, including saddle–node bifurcation, Hopf bifurcation, Bogdanov–Takens bifurcation and cusp bifurcation. Different bifurcation points correspond different types of stress-time curves. The homologous phase diagrams including periodic orbit, unstable orbit and chaotic behavior are presented to show the dynamics diversity of the model. In addition to dynamic analysis, statistical analysis for plasticity values is also applied to excavate the crossover between periodic and chaotic plastic dynamic transitions. Our results provide a novel perspective on the deformation of metallic glasses from the viewpoint of dynamic model and are also important for evaluating the plastic deformation properties of metallic glasses in practical applications.

本文首先通过稀疏识别从金属玻璃的塑性变形中检测出隐藏系统。提取的模型模拟了四种类型的应力-时间曲线,并显示了锯齿状事件的预测结果。这种解释有效地解释了反复屈服的各种实验现象。此外,在对模型进行参数敏感性分析时,以两个参数作为分岔参数,通过对一维分岔和二维分岔的分析,挖掘出动态转变的原因,包括鞍节点分岔、霍普夫分岔、波格丹诺夫-塔肯斯分岔和尖顶分岔。不同的分岔点对应不同类型的应力-时间曲线。为显示模型动力学的多样性,还给出了包括周期轨道、不稳定轨道和混沌行为在内的同源相图。除了动态分析之外,还应用了塑性值统计分析来挖掘周期性和混沌塑性动态转换之间的交叉。我们的研究结果从动态模型的角度为金属玻璃的变形提供了一个新的视角,对于评估金属玻璃在实际应用中的塑性变形特性也具有重要意义。
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引用次数: 0
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International Journal of Non-Linear Mechanics
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