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The nonlinear post-buckling behavior of FG cylindrical copper shell reinforced with carbon nanotubes with a polymer core 碳纳米管增强具有聚合物芯的FG圆柱铜壳的非线性后屈曲行为
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-12-01 DOI: 10.1007/s00419-024-02710-6
Masoud Ajri

This research analyzes the buckling and post-buckling behavior of composite cylindrical shells with a polymer core and carbon nanotube-reinforced inner and outer copper layers with functional distribution under axial compressive loading. For this purpose, the differential equations governing the nonlinear buckling behavior of these shells were extracted while considering large deformations. Employing the Ritz energy method and considering the Airy function, analytical relations for the buckling load and the critical stress of the structure are extracted. In the following, considering different distributions, the equivalent mechanical properties of the composite structure have been calculated using the law of mixtures. Finally, the effect of different parameters, such as distribution types and volume fraction of nanotubes, on nonlinear buckling loads and post-buckling behavior of these materials is investigated. Results show that increasing the volume fraction of carbon nanotubes reduces the change in the critical length of the cylindrical shell, which happens as a result of increasing Young's modulus and the equivalent stiffness of the shell.

本研究分析了具有功能分布的聚合物芯和碳纳米管增强内外铜层复合材料圆柱壳在轴向压缩载荷作用下的屈曲和后屈曲行为。为此,在考虑大变形的情况下,提取了控制这些壳的非线性屈曲行为的微分方程。采用里兹能量法,考虑Airy函数,导出了结构屈曲载荷与临界应力的解析关系。下面,考虑不同的分布,利用混合定律计算复合材料结构的等效力学性能。最后,研究了纳米管的分布类型和体积分数等不同参数对材料非线性屈曲载荷和后屈曲行为的影响。结果表明,碳纳米管体积分数的增加减小了柱壳临界长度的变化,这是由于壳的杨氏模量和等效刚度的增加而引起的。
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引用次数: 0
Crack shape evolution of single edge through cracked specimens under mode-I loading I 模式加载下单边贯通裂纹试样的裂纹形状演变
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02705-3
Yongfang Li, Mingming Ren, Hao Chen, Yali Yang, Sha Xu, Ruoping Zhang

Crack shape evolution of single edge through cracked specimens under mode-I loading is studied by means of theoretical analysis, numerical simulation and experimental investigation. Firstly, based on the Paris formula and taking into account the effective stress intensity factor range ratio (U), which characterizes the degree of crack closure, a modified crack growth rate equation is derived. Then, taking the 10 mm thick Al 6061-T6 alloy plate as an example, numerical simulation analysis is conducted. The shape change of crack front during crack propagation is characterized by tunnel depth and surface angle. Finally, fatigue crack growth test is conducted adopting the crack front marking technique to validate the simulation results. The results indicate that the crack growth rate is mainly controlled by the maximum stress intensity factor (Kmax) and the U under a certain stress ratio (R). The crack propagation mainly includes two stages, the initial crack propagation stage and the stable crack propagation stage. During the initial crack propagation stage, the crack growth rate in the central layer is greater than that in the surface layer. After approximately 4 mm of crack growth in the central layer, the crack propagation enters the stable stage. In the stable crack propagation stage, the growth rate of the entire crack front is similar, and the shape of the crack front remains almost unchanged.

通过理论分析、数值模拟和实验研究,研究了单边贯通裂纹试样在模态 I 加载下的裂纹形状演变。首先,以巴黎公式为基础,考虑到表征裂纹闭合程度的有效应力强度因子范围比(U),推导出修正的裂纹增长率方程。然后,以 10 毫米厚的 Al 6061-T6 合金板为例,进行了数值模拟分析。裂纹扩展过程中裂纹前沿的形状变化由隧道深度和表面角度表征。最后,采用裂纹前沿标记技术进行了疲劳裂纹生长试验,以验证模拟结果。结果表明,裂纹增长速度主要受最大应力强度因子(Kmax)和一定应力比(R)下的 U 控制。裂纹扩展主要包括两个阶段,即初始裂纹扩展阶段和稳定裂纹扩展阶段。在初始裂纹扩展阶段,中心层的裂纹增长速度大于表层。在中心层裂纹增长约 4 毫米后,裂纹扩展进入稳定阶段。在稳定的裂纹扩展阶段,整个裂纹前沿的增长速度相似,裂纹前沿的形状几乎保持不变。
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引用次数: 0
The influence of disks deformation on the stability analysis of an aircraft braking system 制动盘变形对飞机制动系统稳定性分析的影响
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02715-1
X. Fagan, J. -J. Sinou, S. Besset, L. Jézéquel, A. Hamdi

Friction-induced vibration emanating from aircraft braking system is a key issue in the design phase, due to the significant damage it can cause to the brake structure. Although the problem of unstable vibrations in aircraft braking systems has been studied by a number of researchers, the suitability of the mechanical modeling strategy for predicting instabilities remains an open problem. The need for relevant numerical models is therefore essential in order to be as predictive as possible during the design phase. Preliminary studies must therefore be carried out to validate or invalidate the modeling hypotheses traditionally used. Indeed the stability analysis of an aircraft braking system is performed in order to study a low-frequency instability. An industrial model is used, hence reducing the number of degrees of freedom (DoF) is of utmost importance in order to have reasonable computation times. When studying low-frequency phenomena, this can be achieved by neglecting the deformations of the disks. However, no current study has shown that this hypothesis is realistic. So the aim of this paper is to assess the effect of the rigidity hypothesis on the results predicted by the stability analysis. In order to do so, the stability analysis results of a model with rigid disks and one with non-rigid disks are compared, with a particular attention on the main instability phenomenon. It is found that considering rigid disks has a very limited influence on the frequency of the low-frequency eigenmodes, but it over-predicts the real part of the unstable eigenmode. Besides, a component mode synthesis (CMS) technique is shown to reduce significantly the size of the non-rigid disks model while ensuring a satisfying precision regarding eigenmodes prediction.

飞机制动系统产生的摩擦引起的振动是设计阶段的一个关键问题,因为它可能对制动结构造成重大损害。尽管许多研究人员已经对飞机制动系统中的不稳定振动问题进行了研究,但用于预测不稳定性的机械建模策略的适用性仍是一个未决问题。因此,必须建立相关的数值模型,以便在设计阶段尽可能地进行预测。因此,必须进行初步研究,以验证或推翻传统使用的建模假设。事实上,对飞机制动系统进行稳定性分析就是为了研究低频不稳定性。由于使用的是工业模型,因此减少自由度(DoF)数量对于获得合理的计算时间至关重要。在研究低频现象时,可以通过忽略磁盘的变形来实现这一点。然而,目前还没有研究表明这一假设是现实的。因此,本文旨在评估刚性假设对稳定性分析预测结果的影响。为此,本文比较了刚性盘模型和非刚性盘模型的稳定性分析结果,并特别关注了主要的不稳定现象。结果发现,考虑刚性盘对低频特征模态频率的影响非常有限,但却过度预测了不稳定特征模态的实际部分。此外,研究还显示了一种分量模式合成(CMS)技术,该技术可显著减小非刚性磁盘模型的大小,同时确保对特征模式的预测精度令人满意。
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引用次数: 0
Peeling and large deformation of the magneto-responsive slender sheet adhered by a liquid film 液体薄膜粘附的磁响应薄片的剥离和大变形
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02726-y
Yizhe Zhu, Gongqi Cao, Xiaoxuan Ding, Shiyang Liu, Yuchen Jin, Jianlin Liu

Intelligent magneto-responsive structures are widely used due to their fast response speed and noncontact control. In this study, the peeling behavior of a slender magneto-responsive sheet under the magnetic field's action is investigated experimentally and theoretically. Firstly, two identical magneto-responsive sheets, with the liquid film adhesion and the absence of the liquid film respectively, are analyzed under the control of a cylindrical magnet. In addition, the peeling process is abstracted via the classical elastica model, and the expression of the potential energy functional is established. The approximate solutions of the deflection and the adhesion length of the magneto-responsive sheets during the peeling process are obtained based on the Rayleigh–Ritz method. The effects of the magnetic field generated by cylindrical magnets and the work of adhesion on the maximum deflection and adhesion length of magneto-responsive sheets are further predicted. The theoretically approximate solution agrees very well with the experimental data. These findings can provide new implications in a wide range of industrial areas, such as medical microsensors and intelligent structures for drug delivery.

智能磁响应结构因其快速响应和非接触控制而得到广泛应用。本研究通过实验和理论研究了细长磁响应片在磁场作用下的剥离行为。首先,在圆柱形磁铁的控制下,分析了两块相同的磁敏薄片,它们分别有液膜附着和无液膜附着。此外,通过经典弹性模型抽象出剥离过程,并建立了势能函数的表达式。基于 Rayleigh-Ritz 方法,得到了剥离过程中磁响应片的挠度和粘附长度的近似解。进一步预测了圆柱形磁铁产生的磁场和粘附功对磁响应片最大挠度和粘附长度的影响。理论近似解与实验数据非常吻合。这些发现将为医疗微传感器和用于药物输送的智能结构等广泛的工业领域提供新的启示。
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引用次数: 0
Tire vibration analysis of three-dimensional flexible ring with brush model under static contact conditions by using frequency-based substructuring 利用基于频率的子结构对静态接触条件下带刷子模型的三维柔性环进行轮胎振动分析
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02725-z
Masami Matsubara, Akira Saito, Chang Po-Siang, Shozo Kawamura

The use of a simplified physical model of the tire of road vehicles is an efficient and simultaneous method to study the specifications of the entire chassis, including the tire specifications. Therefore, it is important to develop a simplified physical model that can be used in the early design phase when detailed computer-aided design data are not available. In this study, a vibration analysis of tires in road contact is described using frequency-based substructuring in a three-dimensional elastic ring model of a tire that includes a brush model simulating the tread rubber. By modeling the brush as a contact spring between the tire and the road surface, the natural frequencies and mode shapes of the tire under load conditions can be calculated using point-coupled three-way contact spring constraints. The experimental results show that the natural frequency changes significantly with road contact and does not depend on the vertical load. The theoretical analysis also showed that the natural frequency does not change when the stiffness of the contact spring is large enough to limit the displacement of the road contact, which is consistent with the experimental results. Unlike previous studies, this method calculates the mode shape with road contact based on the mode shape without road contact; therefore, the required model parameters can be determined based on the experimental modal analysis for the free-free condition.

使用公路车辆轮胎的简化物理模型是研究整个底盘规格(包括轮胎规格)的一种有效且同步的方法。因此,在没有详细计算机辅助设计数据的情况下,开发一种可用于早期设计阶段的简化物理模型非常重要。在本研究中,使用基于频率的子结构来描述轮胎与路面接触时的振动分析,该模型是轮胎的三维弹性环模型,其中包括模拟胎面橡胶的刷子模型。通过将刷子建模为轮胎与路面之间的接触弹簧,可以利用点耦合三向接触弹簧约束计算出轮胎在负载条件下的固有频率和模态振型。实验结果表明,固有频率随路面接触而发生显著变化,且与垂直载荷无关。理论分析也表明,当接触弹簧的刚度大到足以限制路面接触位移时,固有频率不会发生变化,这与实验结果一致。与以往的研究不同,该方法是根据无道路接触的模态振型来计算有道路接触的模态振型;因此,可以根据自由状态下的实验模态分析来确定所需的模型参数。
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引用次数: 0
Loss factor analysis in real-time structural health monitoring using a convolutional neural network 利用卷积神经网络进行实时结构健康监测中的损失因子分析
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02712-4
Thanh Q. Nguyen, Tu B. Vu, Niusha Shafiabady, Thuy T. Nguyen, Phuoc T. Nguyen

This study presents a novel approach to real-time structural health monitoring employing convolutional neural networks (CNN) to calculate a loss factor that measures energy dissipation in structures. As mechanical properties degrade over time due to service loads, timely detection of defects is crucial for ensuring safety. The loss factor, derived from the vibration energy spectrum, is used to identify structural changes, distinguishing between normal operation, the presence of defects, and noise interference. Using large data from real-time vibration signals, this method enables continuous and accurate monitoring of structural integrity. The proposed CNN model outperforms traditional models such as multilayer perceptron and long short-term memory, demonstrating superior accuracy in detecting early-stage defects and predicting structural changes. Applied to the Saigon Bridge, the method offers valuable insight into long-term structural behavior and provides a reliable tool for proactive maintenance and safety management. This research contributes to a machine learning-based solution for improving structural health monitoring systems in critical infrastructure.

本研究提出了一种实时结构健康监测的新方法,利用卷积神经网络(CNN)计算损耗因子,以测量结构中的能量耗散。由于机械性能会随着时间的推移因使用载荷而退化,因此及时发现缺陷对于确保安全至关重要。损耗因子来自振动能量谱,用于识别结构变化,区分正常运行、缺陷存在和噪声干扰。利用来自实时振动信号的大量数据,该方法可对结构完整性进行连续、准确的监测。所提出的 CNN 模型优于多层感知器和长短期记忆等传统模型,在检测早期缺陷和预测结构变化方面表现出卓越的准确性。该方法应用于西贡大桥,为长期结构行为提供了宝贵的见解,并为主动维护和安全管理提供了可靠的工具。这项研究为改进关键基础设施的结构健康监测系统提供了一种基于机器学习的解决方案。
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引用次数: 0
Wavelet analysis of DPL bioheat transfer model for cylindrical tissues during thermal ablation 圆柱形组织热烧蚀过程中 DPL 生物传热模型的小波分析
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02707-1
Pappu Kumar, Dinesh Kumar, Arvind Kumar Yadav, Rakhi Tiwari

This paper numerically investigates the thermal behavior in a cylindrical tissue under non-Fourier boundary condition with dual-phase-lag bioheat transfer problem during thermal ablation. A hybrid method based on Legendre wavelets and finite difference approach are applied to determine an approximate analytic solution of the current problem. The correctness and feasibility of the present numerical scheme has been shown by comparing with exact solution under particular case. It has been observed that lower blood temperature gives rise to lower tissue temperature at the thermal ablation position. So, in order to get precise thermal data for treatment, blood temperature of particular patient must be taken into consideration for patient specific treatment. One of the main objective of this article is to minimize thermal damage outside the thermal ablation position. Our study demonstrates that outside the tumor position, normothermia condition exists, throughout the treatment time that reduces the risk of infection, minimizes thermal damages and ensure that patient feel comfortably well during the period. The specific heating plays a key role in the success of thermal ablation treatment and selection of Gaussian distribution source term helps to achieve the purpose. The radius of heat source, effective radius of heat flux and maximum heat flux generated are the important parameters of Gaussian heat source and computed thermal data strongly depends on them. The variation in the values of radius of heat source allows us specific heating(heating at a particular position) in the thermal ablation process so that the specific tumor can be treated. Both effective radius of heat flux and maximum heat flux applied gives the control of temperature at the thermal ablation position. Moreover, temperature rise at the tumor location is uniform in case of maximum heat flux applied. The present analysis will be helpful for medical community for better use of thermal data during thermal ablation.

本文以数值方法研究了热烧蚀过程中,在非傅里叶边界条件下圆柱形组织中的热行为,以及双相滞后生物传热问题。应用基于 Legendre 小波和有限差分的混合方法确定了当前问题的近似解析解。通过与特定情况下的精确解进行比较,证明了本数值方案的正确性和可行性。据观察,较低的血液温度会降低热消融位置的组织温度。因此,为了获得精确的治疗热数据,必须考虑到特定病人的血液温度,以进行针对病人的治疗。本文的主要目的之一是尽量减少热消融位置外的热损伤。我们的研究表明,在肿瘤位置外,整个治疗过程中都存在常温状态,这可以降低感染风险,最大限度地减少热损伤,并确保患者在治疗期间感觉舒适。特定加热对热消融治疗的成功起着关键作用,选择高斯分布源项有助于实现这一目的。热源半径、热通量有效半径和产生的最大热通量是高斯热源的重要参数,热数据的计算与这些参数密切相关。热源半径值的变化可以在热烧蚀过程中实现特定加热(在特定位置加热),从而治疗特定肿瘤。有效热通量半径和最大热通量都能控制热消融位置的温度。此外,在应用最大热通量的情况下,肿瘤位置的温升是均匀的。本分析将有助于医学界在热消融过程中更好地利用热数据。
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引用次数: 0
Closed-form postbuckling analysis of shear-deformable composite laminated panels 可剪切变形复合层压板的闭式后屈曲分析
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02720-4
Jakob C. Schilling, Christian Mittelstedt

This paper introduces a closed-form analytical approach to the postbuckling analysis of simply supported shear-deformable composite laminated plates under uniaxial compression. The analysis is based on three different laminate theories in order to explicitly account for transverse shear deformations and uses a geometrically nonlinear formulation in conjunction with the Ritz method in order to enable closed-form analytical expressions for the state variables of buckled composite plates. Results are presented for several different plate configurations, and a comparison is performed with literature results as well as comparative finite element computations which leads to a very satisfying results accuracy. The presented analysis method delivers results without any significant numerical effort and is thus especially suited for practical applications where such postbuckling analyses are performed many times.

本文介绍了一种闭式分析方法,用于对单轴向压缩下的简支撑剪切变形复合层压板进行后屈曲分析。该分析基于三种不同的层压板理论,以明确考虑横向剪切变形,并结合 Ritz 方法使用几何非线性公式,以实现屈曲复合板状态变量的闭式分析表达式。该方法给出了几种不同板材配置的结果,并与文献结果和有限元计算结果进行了比较,结果精度非常令人满意。所介绍的分析方法无需大量的数值计算即可得出结果,因此特别适用于需要多次进行此类屈曲后分析的实际应用。
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引用次数: 0
Stability analysis of a hybrid composite rotor with the three-node finite element method 用三节点有限元法对混合复合材料转子进行稳定性分析
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02729-9
Mohammad Mahdi Nazari, Abbas Rahi, Roohollah Sarfaraz Khabbaz

Rotor stability analysis is essential to ensure rotating composite structures' safe and efficient operation. In this paper, the stability analysis of a hybrid composite shaft with two disks placed on elastic supports is investigated by the three-node finite element method. The strain potential energy of the hybrid composite shaft is calculated by considering the Timoshenko beam theory and using shape functions and the ABD matrix's effective components. The governing equations of the composite rotor are derived by replacing the kinetic energy of the shaft and disks, the strain potential energy, and the force of the bearings in the Lagrange equation. The equations of motion obtained from the finite element method are coded in the state space using MATLAB script. Their eigenvalues are calculated as a function of the rotor rotation speed, and the instability threshold of the composite rotor is evaluated. To validate the simulation results of the composite shaft in the free–free state in the ANSYS software, a hybrid composite shaft is made using the filament winding method, and its natural frequencies are extracted by performing the experimental modal analysis test. The instability threshold of the non-hybrid composite rotor of the presented model in different stacking sequences is compared with the results of the previous studies, and the validity of the three-node finite element method is confirmed. Finally, the effect of the fiber angle and the arrangement of the layers in the usage of carbon/epoxy and glass/epoxy in a specific stacking sequence on the stability of the hybrid composite rotor is studied.

转子稳定性分析对于确保旋转复合材料结构的安全高效运行至关重要。本文采用三节点有限元法研究了置于弹性支撑上的双盘混合复合材料轴的稳定性分析。考虑到季莫申科梁理论,并利用形状函数和 ABD 矩阵的有效分量计算了混合复合材料轴的应变势能。通过将轴和盘的动能、应变势能以及轴承的力代入拉格朗日方程,得出了复合转子的控制方程。使用 MATLAB 脚本在状态空间中对有限元法得到的运动方程进行编码。计算其特征值与转子转速的函数关系,并评估复合转子的失稳阈值。为了验证 ANSYS 软件中复合材料转轴自由状态下的仿真结果,使用丝状缠绕法制作了混合复合材料转轴,并通过实验模态分析测试提取了其固有频率。将所提出模型的非混合复合材料转子在不同堆叠顺序下的失稳阈值与之前的研究结果进行了比较,并证实了三节点有限元法的有效性。最后,研究了在特定堆叠顺序中使用碳/环氧树脂和玻璃/环氧树脂时纤维角度和层的排列对混合复合材料转子稳定性的影响。
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引用次数: 0
Penalty 4-node quadrilateral element formulation for axisymmetric-torsion problems within consistent couple stress theory 一致耦合应力理论中轴对称扭转问题的惩罚性四节点四边形元素公式
IF 2.2 3区 工程技术 Q2 MECHANICS Pub Date : 2024-11-29 DOI: 10.1007/s00419-024-02706-2
Yong-Kang Jiang, Yan Shang

In this work, a novel quadrilateral four-node element capable of simulating the axisymmetric-torsion deformation of small-scale solids of revolution is developed based on the consistent couple stress theory (CCST). To establish the element formulation, the C1 requirement for displacement in the CCST is enforced in weak sense by using the penalty function method and the independent nodal rotation degrees of freedom are introduced into element construction to approximate the mechanical rotation fields. Besides, the stress functions that can satisfy the relevant equilibrium equation of the axisymmetric-torsion deformation are adopted as the basic functions for designing the element’s stress trial function. Several numerical tests are carried out and the results are compared to the solutions obtained using the analytical method or hexahedral solid element from the literature. It is shown that the new element exhibits good accuracy and captures the size dependences efficiently in prediction of the axisymmetric-torsion behavior of small-scale solids.

本研究以一致耦合应力理论(CCST)为基础,开发了一种新型四边形四节点元素,能够模拟小尺寸旋转实体的轴对称扭转变形。在建立元素配方时,使用惩罚函数方法弱化了 CCST 中对位移的 C1 要求,并在元素构造中引入了独立节点旋转自由度以近似机械旋转场。此外,采用能满足轴对称扭转变形相关平衡方程的应力函数作为设计元素应力试算函数的基本函数。我们进行了多次数值试验,并将试验结果与使用分析方法或文献中的六面体实体元素求解的结果进行了比较。结果表明,在预测小尺度固体的轴对称扭转行为时,新元素具有良好的准确性,并能有效捕捉尺寸相关性。
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引用次数: 0
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Archive of Applied Mechanics
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