International Journal of Non-Linear Mechanics最新文献_第9页

Numerical simulation of stress and permeability evolution in damaged coal 受损煤炭中应力和渗透率演变的数值模拟

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-11-13 DOI: 10.1016/j.ijnonlinmec.2024.104953

Xianghe Gao , Feng Gao , Ning Zhang , Hongmei Cheng , Yan Xing

Mining disturbance is the underlying cause of dynamic disasters such as coal-rock deformation, gas outbursts, and roof water inrush. Mining disturbance leads to damage in coal-rock structures and closely relates to stope cracks' distribution characteristics. Therefore, it is crucial to investigate the coupling effects of the stress field, damage field, and seepage field of coal. Firstly, we established a mechanical model considering the coupling effect of damage and elastoplasticity, which aimed to describe the softening process of coal-rock mechanical parameters and the mutation law of the permeability coefficient in the damage process. Next, we developed a pore-fracture fractal model of damaged coal. It was used to elucidate the inherent relationship between damage and pore-fracture characteristics in the process of coal-rock crushing. We then proposed a quantitative evaluation method for determining the permeability characteristics of coal under the influence of mining disturbances. Finally, a numerical simulation of damaged coal ‘s mechanical behavior and seepage characteristics under stress-seepage coupling was conducted. The development model's effectiveness was verified through comparison with experimental results. In summary, our research offered a solid scientific foundation for quantitative evaluation and accurate prediction of the evolution law of coal-rock permeability characteristics under the influence of mining disturbance.

采动扰动是煤岩变形、瓦斯突出、顶板涌水等动力灾害的根本原因。开采扰动导致煤岩结构破坏，并与斜坡裂缝分布特征密切相关。因此，研究煤的应力场、破坏场和渗流场的耦合效应至关重要。首先，我们建立了考虑损伤与弹塑性耦合效应的力学模型，旨在描述损伤过程中煤岩力学参数的软化过程和渗透系数的突变规律。接着，我们建立了受损煤的孔隙-断裂分形模型。该模型用于阐明煤岩破碎过程中损伤与孔隙-断裂特征之间的内在关系。然后，我们提出了确定煤炭在采矿扰动影响下透气性特征的定量评价方法。最后，对应力-渗流耦合作用下受损煤的力学行为和渗流特性进行了数值模拟。通过与实验结果的对比，验证了开发模型的有效性。总之，我们的研究为定量评价和准确预测采矿扰动影响下煤岩透气性特征的演变规律提供了坚实的科学基础。

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引用次数: 0

Stick–slip oscillations in the low feed linear motion of a grinding machine due to dry friction and backlash 磨床低进给直线运动中因干摩擦和反向间隙引起的粘滑振动

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-11-06 DOI: 10.1016/j.ijnonlinmec.2024.104940

Zsolt Iklodi , Petri T. Piiroinen , Oier Franco , Xavier Beudaert , Zoltan Dombovari

This paper deals with mechanical modelling and numerical bifurcation analysis of stick–slip oscillations that plague extremely low feed grinding operations. Based on experimental observations, a novel two degree of freedom mechanical model of a grinding machine feed drive system is formulated, which incorporates Stribeck-type dry friction, position and velocity controller dynamics, and actuator backlash. Loss and re-establishment of contact between the feed drive elements is modelled through both rigid-body impacts and a contact-stiffness model. The resulting piecewise-smooth equations of motion are subjected to detailed stability and bifurcation analysis with the help of shooting and collocation based numerical continuation tools. Major focus is attributed to the influence of the feed velocity and the control-loop parameters as well as the identification of stable, stick–slip free parameter regimes. Finally, a controller enhancement strategy is proposed, based on event-driven integrator reset rules, to help limit the amplitude of arising limit-cycle oscillations.

本文论述了困扰极低进给量磨削操作的粘滑振荡的机械建模和数值分岔分析。根据实验观察结果，建立了磨床进给驱动系统的新型双自由度机械模型，其中包含 Stribeck 型干摩擦、位置和速度控制器动态以及执行器反向间隙。通过刚体冲击和接触刚度模型对进给驱动元件之间的接触损失和重新建立进行建模。借助基于射击和配位的数值延续工具，对由此产生的片式平滑运动方程进行了详细的稳定性和分岔分析。主要重点是进给速度和控制回路参数的影响，以及稳定的无粘滑参数区的识别。最后，提出了一种基于事件驱动积分器重置规则的控制器增强策略，以帮助限制极限周期振荡的幅度。

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引用次数: 0

Research on rigid-flexible coupling nonlinear dynamics of light commercial vehicle considering frame flexibility

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-11-05 DOI: 10.1016/j.ijnonlinmec.2024.104949

Shuai Mo , Keren Chen , Yingxin Zhang , Yuansheng Zhou , Liangyuan Lyu , Bowei Yao , Wei Zhang

Commercial vehicles play a vital role in the transportation industry. Generally, there will present a complex nonlinear dynamic behavior composed of periodic, quasi-periodic, and even chaotic vibration in vehicle vertical system under the continuous speed bump excitation. To explore the nonlinear dynamic behavior of vehicle system, a new rigid-flexible coupling nonlinear dynamic model for light commercial vehicle has been developed theoretically with considering the frame flexibility, suspension stiffness and damping nonlinearity, and rubber bushing nonlinearity. The dynamic model for frame and suspension have been developed with discrete element method and lumped mass method, respectively. Then, the flexible frame model has been verified through the mode shape and frequency calculated by finite element simulation. And the rigid-flexible coupling nonlinear dynamic model of a light commercial vehicle has been verified with Adams simulation and testing results. Furthermore, the influence of vehicle speed and the height of speed bump, suspension stiffness and damping, as well as cargo weight and distribution on vehicle system dynamics is analyzed with bifurcation diagram, time history, frequency, phase diagram and Poincare section. The results show the significant and complex effects on the nonlinear vibration of vehicle system, especially the nonlinear damping and the flexible frame.

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引用次数: 0

Efficient structural optimization under transient impact loads using multilayer perceptron and genetic algorithms 利用多层感知器和遗传算法对瞬态冲击载荷下的结构进行高效优化

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-11-05 DOI: 10.1016/j.ijnonlinmec.2024.104950

Haojie Ma , Xiao Kang , Shengyu Duan , Ying Li

Currently, there is a lack of structural optimization methods when a structure is suffering transient impact load, considering nonlinear factors such as material plasticity and strain rate effect. The utilization of derivative-free algorithms also increases computational expenses. Accordingly, this paper presents a novel structure transient optimization approach based on multilayer perceptron combined with a derivative-free optimization method, which can efficiently solve the transient structure dynamics optimization problem with multiple optimization objects. In this approach, the area to be optimized is cut by several closed B-spline curves whose shapes are controlled by several parameters and can be varied and merged at each optimization iteration step. The structure's transient analysis process is replaced by a machine learning based surrogate model, which is trained by thousands of results from the FEM explicit transient simulation. Additionally, nearly orthogonal Latin hypercube sampling is utilized to simplify parameter dimensionality, reduce the training data set, save calculation time, and give the training data set a more comprehensive range of design parameters. In our optimization process, our design target is to minimize the peak reaction force while with the constrain of ensuring enough stiffness and mass. The results demonstrate our proposed methods could efficiently handle transient optimization problems without sensitivity calculations, exhibiting strong generalization capabilities.

目前，当结构承受瞬态冲击载荷时，考虑到材料塑性和应变率效应等非线性因素，还缺乏结构优化方法。无导数算法的使用也增加了计算费用。因此，本文提出了一种基于多层感知器的新型结构瞬态优化方法，结合无导数优化方法，可以高效解决具有多个优化对象的瞬态结构动力学优化问题。在该方法中，待优化区域由多条封闭的 B-样条曲线切割而成，这些曲线的形状由多个参数控制，并可在每个优化迭代步骤中进行变化和合并。结构的瞬态分析过程由基于机器学习的代用模型取代，该代用模型是由成千上万的有限元显式瞬态模拟结果训练而成的。此外，还利用近乎正交的拉丁超立方采样来简化参数维度、减少训练数据集、节省计算时间，并使训练数据集具有更全面的设计参数范围。在优化过程中，我们的设计目标是在保证足够刚度和质量的前提下，使峰值反作用力最小。结果表明，我们提出的方法无需灵敏度计算即可高效处理瞬态优化问题，具有很强的泛化能力。

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引用次数: 0

Bursting oscillations with multiple crossing bifurcations in a piecewise-smooth system 片状平稳系统中具有多重交叉分岔的猝发振荡

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-11-04 DOI: 10.1016/j.ijnonlinmec.2024.104938

Ying Wang , Zhixiang Wang , Chun Zhang , Qinsheng Bi

This paper aims to investigate the non-smooth bifurcations and to uncover the underlying dynamics that lead to bursting patterns within a two-scale piecewise-smooth system. The system is established by applying a modification scheme to a fourth-order Chua’s circuit, with a periodic external excitation current acting as the slow state variable. Several smooth as well as non-smooth bifurcations are discovered within the fast subsystem by utilizing theoretical and numerical methods. Two special non-smooth bifurcations have been discussed. The first is the multiple crossing bifurcation involving the boundary equilibrium, which exhibits the behavior of both the turning point and Hopf bifurcation. The second arises from an encounter between a saddle-focus and the trajectory of a non-smooth chaotic solution, which can result in the vanishing or appearance of a non-smooth chaotic attractor. Four typical bursting patterns associated with these two non-smooth bifurcations in the established slow–fast system are observed, and the mechanisms behind them are revealed based on bifurcation analysis.

本文旨在研究非光滑分岔，并揭示导致二尺度片状光滑系统中迸发模式的基本动力学。该系统是通过对一个四阶蔡氏电路采用修正方案而建立的，并以周期性外部激励电流作为慢态变量。利用理论和数值方法，在快速子系统中发现了几个平滑和非平滑分岔。其中讨论了两个特殊的非平滑分岔。第一个是涉及边界平衡的多重交叉分岔，它同时表现出转折点和霍普夫分岔的行为。第二种分岔源于鞍状焦点与非光滑混沌解轨迹的相遇，可能导致非光滑混沌吸引子的消失或出现。在已建立的慢-快系统中，观察到与这两种非光滑分岔相关的四种典型猝发模式，并根据分岔分析揭示了其背后的机制。

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引用次数: 0

Effect of geometric variations on the wing rock of blended wing–body aircraft 几何变化对混合翼身飞机机翼岩石的影响

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-11-03 DOI: 10.1016/j.ijnonlinmec.2024.104934

Waseeq Siddiqui , Adnan Maqsood , Shuaib Salamat , Hongyi Xu , Dan Xie

Blended wing–body configurations are anticipated to dominate future transport and military aerospace designs. The departure of the conventional tube-wing configuration has opened several areas of investigation. These designs are susceptible to lateral instability during landing, takeoff, and maneuvering flight despite having improved aerodynamics because of their tailless nature. One of these instabilities, Wing-Rock, poses significant performance and operational difficulties and can potentially cause crashes. Though experimental and numerical studies of the aerodynamics and stability of blended wing–body configurations have been conducted, wing-rock characteristics still need to be identified in the literature. This research aims to investigate these characteristics at low subsonic speeds with varying outboard sweep and geometric twist angles. The study includes a numerical approach based on the rigid body free-vibration method in single roll degree of motion, which uses three-dimensional unsteady Reynolds’ Average Navier Stokes equations, and an analytical approach based on the multiple time scale method, which captures the crucial aspect of the wing rock system. The findings show that the geometrical parameters significantly impact the wing rock characteristics, which are unique to such novel tailless designs.

混合翼身结构预计将在未来的运输和军用航空航天设计中占据主导地位。传统管翼构型的消失开辟了多个研究领域。尽管这些设计的无尾特性改善了空气动力学性能，但在着陆、起飞和机动飞行过程中仍容易出现横向不稳定性。其中一种不稳定性，即 "翼摇"（Wing-Rock），给性能和操作带来了极大的困难，并有可能导致坠机。虽然已经对混合翼身构型的空气动力学和稳定性进行了实验和数值研究，但仍需在文献中确定翼摇特性。本研究旨在研究在低亚音速条件下，不同外掠角和几何扭转角下的翼摇特性。研究包括基于单滚动度运动刚体自由振动法的数值方法（该方法使用三维非稳态雷诺平均纳维-斯托克斯方程）和基于多时间尺度法的分析方法（该方法抓住了翼岩系统的关键方面）。研究结果表明，几何参数极大地影响了翼岩石的特性，这是此类新型无尾设计所独有的。

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引用次数: 0

Data-driven bifurcation analysis using parameter-dependent trajectories 利用参数轨迹进行数据驱动的分岔分析

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-11-01 DOI: 10.1016/j.ijnonlinmec.2024.104937

Jesús García Pérez , Leonardo Sanches , Amin Ghadami , Guilhem Michon , Bogdan Epureanu

Identification of bifurcation diagrams in nonlinear systems is of great importance for resilient design and stability analysis of dynamical systems. Data-driven identification of bifurcation diagrams has a significant advantage for large dimensional systems where analysis of the equations is not possible, and for experimental systems where accurate system equations are not available. In this work, a novel forecasting approach to predict bifurcation diagrams in nonlinear systems is presented using system trajectories before instabilities occur. Unlike previous techniques, the proposed method considers a varying bifurcation parameter during the system response to perturbations. Combined with an asymptotic analysis provided by the method of multiple scales eliminates the requirement of using multiple measurements and allows the novel technique to predict the bifurcation diagram using a single system recovery. The proposed approach allows stability analyses of nonlinear systems with limited access to experimental or surrogate data. The novel technique is demonstrated through its application to a Hopf bifurcation, highlighting its inherent advantages. Subsequently, the method is employed in the analysis of an aeroelastic system that shows both supercritical and subcritical Hopf bifurcations. The findings reveal great accuracy, achieved with a reduced number of measurements, while enhancing versatility.

识别非线性系统中的分岔图对于动态系统的弹性设计和稳定性分析非常重要。对于无法分析方程的大维度系统和无法获得精确系统方程的实验系统，数据驱动的分岔图识别具有显著优势。本研究提出了一种新颖的预测方法，利用不稳定性发生前的系统轨迹预测非线性系统的分岔图。与以往的技术不同，所提出的方法考虑了系统对扰动响应过程中分岔参数的变化。结合多尺度方法提供的渐近分析，消除了使用多次测量的要求，使新技术能够使用单一系统恢复来预测分岔图。利用所提出的方法，可以对实验数据或替代数据有限的非线性系统进行稳定性分析。新技术通过应用于霍普夫分岔进行了演示，突出了其固有优势。随后，该方法被用于分析一个同时出现超临界和亚临界霍普夫分岔的气动弹性系统。研究结果表明，该方法在提高通用性的同时，通过减少测量次数实现了极高的精确度。

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引用次数: 0

Nonlinear vibration analysis of composite and functionally graded material shell structures: A literature review from 2013 to 2023 复合材料和功能分级材料壳体结构的非线性振动分析：2013 至 2023 年文献综述

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-10-30 DOI: 10.1016/j.ijnonlinmec.2024.104939

Vignesh Palani, Ashirbad Swain

Owing to the improved mechanical properties of composites and functionally graded materials (FGMs), their applications have been realised in various engineering domains, such as aerospace, marine, automobile, and defence. Materials’ property plays a crucial role in dictating the dynamics of shell structure. Although much research has been conducted in structural dynamics, researchers are still working to develop new theories for structure and materials for composite shell structures to investigate their dynamic behaviour with various computational approaches involving different shell theories and experimental techniques. Apart from the linear analysis, researchers have also focused on the nonlinear dynamic behaviour of the shell structure with various shell theories. But still, this field of research remains vibrant for many researchers. This review encapsulates some critical articles in the field of the dynamics of both composite and FGM shell structures involving nanocomposite, viscoelastic and hyperelastic material systems. The motive of the study is also to highlight the analyses of the shear deformation theories employed for the development of formulations of shell structures, including geometrical and material nonlinearity, for the analysis of the dynamics involved in closed shells, panels, and such structures under fluid-structure interaction.

由于复合材料和功能分级材料（FGMs）的机械性能得到改善，它们已在航空航天、航海、汽车和国防等多个工程领域得到应用。材料的特性在决定壳体结构的动力学方面起着至关重要的作用。尽管在结构动力学方面已经开展了大量研究，但研究人员仍在努力为复合材料壳体结构开发新的结构和材料理论，通过涉及不同壳体理论和实验技术的各种计算方法来研究其动态行为。除线性分析外，研究人员还利用各种壳理论重点研究壳结构的非线性动态行为。但对于许多研究人员来说，这一研究领域仍然充满活力。本综述囊括了复合材料和 FGM 壳体结构动力学领域的一些重要文章，涉及纳米复合材料、粘弹性和超弹性材料系统。本研究的目的还在于重点分析在开发壳体结构配方时采用的剪切变形理论，包括几何非线性和材料非线性，以分析流固耦合作用下封闭壳体、面板和此类结构的动力学。

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引用次数: 0

Flow of fluids with pressure-dependent viscosity down an incline: Long-wave linear stability analysis 粘度随压力变化的流体沿斜面向下流动：长波线性稳定性分析

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-10-28 DOI: 10.1016/j.ijnonlinmec.2024.104930

Benedetta Calusi

In this paper, we investigate the linear stability of a gravity-driven fluid with pressure-dependent viscosity flowing down an inclined plane. The linear stability analysis is formulated using the long-wave approximation method. We show that the onset of instability occurs at a critical Reynolds number that depends on the material and geometrical parameters. Our results suggest that the dependence of the viscosity on pressure can influence the stability characteristics of the flow down an incline.

本文研究了流体在重力驱动下的线性稳定性，该流体的粘度与压力有关。线性稳定性分析采用长波近似法。结果表明，不稳定性发生在一个临界雷诺数上，而这个临界雷诺数取决于材料和几何参数。我们的结果表明，粘度对压力的依赖会影响斜面下流动的稳定性特征。

引用次数: 0

Shakedown analysis of incompressible materials under cyclic loads: A locking-free CS-FEM-Q5 numerical approach 循环载荷下不可压缩材料的晃动分析：无锁定 CS-FEM-Q5 数值方法

IF 2.8 3区工程技术 Q2 MECHANICS

International Journal of Non-Linear Mechanics

Pub Date : 2024-10-28 DOI: 10.1016/j.ijnonlinmec.2024.104932

Phuc L.H. Ho , Changkye Lee , Canh V. Le , Jurng-Jae Yee

Volumetric locking may occur in plastic analysis of incompressible materials using low-order finite elements due to incompressibility constraints. This study presents a locking-free smoothed five-node quadrilateral element-based approach for plastic analysis in structural engineering. The proposed Q5-element employing four cell-based smoothing domains effectively alleviates the volumetric locking issues, here in the problems under plane strain conditions. The resulting large-scale optimization problem is formulated in a conic programming form, enabling efficient use of the interior-point optimizer. Numerical investigations demonstrate the method’s effectiveness in alleviating volumetric locking, accurately predicting collapse and shakedown limits, and generating interaction diagrams for load-carrying capacity and structural collapse mechanisms.

由于不可压缩性的限制，使用低阶有限元对不可压缩材料进行塑性分析时可能会出现体积锁定。本研究提出了一种基于平滑五节点四边形元素的无锁定方法，用于结构工程中的塑性分析。所提出的 Q5 元素采用四个基于单元的平滑域，有效缓解了平面应变条件下的体积锁定问题。由此产生的大规模优化问题采用圆锥编程形式，从而可以高效地使用内点优化器。数值研究表明，该方法能有效缓解体积锁定问题，准确预测坍塌和晃动极限，并生成承载能力和结构坍塌机制的相互作用图。

引用次数: 0