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【新文速递】2023年12月21日固体力学SCI期刊最新文章

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今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 9 篇

International Journal of Solids and Structures

Analysis of the Mullins effect in buckling instability of double-network hydrogel beams under swelling equilibrium

Pingping Zhu, Zheng Zhong

doi:10.1016/j.ijsolstr.2023.112627

膨胀平衡下双网水凝胶梁屈曲不稳定性中的穆林斯效应分析

Due to their outstanding physical and mechanical properties, double-network (DN) hydrogels have gained a most attention among various synthetic tough hydrogels. The Mullins effect and buckling instability are two frequent phenomena that may occur simultaneously in slender DN hydrogel structures as high load-bearing candidates. The swelling/deswelling degree of the DN hydrogel affects the coupling phenomena. It is essential to understanding the interplay between these behaviors. In this work, a physically based damage constitutive model for a DN polymer under water-diffusion equilibrium and cyclic loadings is developed. This theory of coupled swelling and load-induced deformations show good capability in capturing the Mullins effect of swollen DN hydrogels and the corresponding swelling ratio. The model parameters are determined by fitting experimental data of a freely swollen DN hydrogel under cyclic compression. Based on the constitutive model and determined parameters, the buckling instability of DN hydrogel beams is studied via the analytical formula of incremental modulus. The stability diagrams of the DN hydrogel beams under virgin loading and reloading are presented. The influences of stress softening, strain stiffening and chemical potential on buckling conditions for compressive stress and slenderness ratio are thoroughly analyzed. It demonstrates that the stress softening is dramatically against the stability of the beam, but the strain-stiffening effect would conversely help widen the stable range. Besides, it is found that a DN gel beam immersed in a sufficient low chemical potential environment has better buckling stability. These theoretical results are valuable in the preparation and structural design of DN hydrogels for repeated use purpose.

双网(DN)水凝胶因其出色的物理和机械性能,在各种合成韧性水凝胶中最受关注。Mullins 效应和屈曲不稳定性是作为高承载候选材料的细长 DN 水凝胶结构中可能同时出现的两种常见现象。DN 水凝胶的膨胀/溶胀程度会影响耦合现象。了解这些行为之间的相互作用至关重要。在这项研究中,我们开发了一种基于物理的 DN 聚合物在水扩散平衡和循环负载条件下的损伤构成模型。这种溶胀和载荷诱导变形耦合理论在捕捉溶胀 DN 水凝胶的 Mullins 效应和相应的溶胀率方面表现出良好的能力。模型参数是通过拟合循环压缩下自由膨胀 DN 水凝胶的实验数据确定的。根据构成模型和确定的参数,通过增量模量解析公式研究了 DN 水凝胶梁的屈曲不稳定性。给出了 DN 水凝胶梁在原始加载和再加载条件下的稳定性图。深入分析了应力软化、应变硬化和化学势对压应力和纤度比屈曲条件的影响。结果表明,应力软化会极大地影响梁的稳定性,而应变加固效应则有助于扩大稳定范围。此外,研究还发现,浸泡在足够低的化学势环境中的 DN 凝胶梁具有更好的屈曲稳定性。这些理论结果对重复使用的 DN 水凝胶的制备和结构设计很有价值。


Mechanics of Materials

A continuum-micromechanical model for crazing in glassy polymers under cyclic loading

Tobias Laschuetza, Thomas Seelig

doi:10.1016/j.mechmat.2023.104901

循环加载下玻璃态聚合物开裂的连续微观力学模型

A micromechanics-inspired constitutive model is developed to describe the deformation behaviour of fibrillated material within crazes in glassy polymers subjected to cyclic loading. In a finite strain setting, the model accounts for the morphology change taking place by the drawing of material from the intact bulk polymer into craze fibrils and their transition from primitive to mature fibrils. Building on previous research, fibril drawing is described as a viscoplastic process. A novel contribution of this study is the incorporation of viscoelastic deformation of existing fibrils, which is motivated by experimental observations. This new perspective allows for creep recovery, especially during the unloading phases of cyclic deformation. A parameter study which pays special attention to the role of the characteristic times scales of fibril drawing and fibril creep in relation to the imposed loading rate illustrates the performance of the model. Since the model is designed as an input to cohesive fracture simulations in glassy polymers, its response under monotonic loading is analysed and compared to existing crazing models. Of primary interest, however, is the model behaviour under cyclic loading which is investigated for different loading scenarios up to fibril failure. The study highlights the complex interplay between the two viscous mechanisms and how they influence the local deformation behaviour of the craze matter as well as the number of cycles until failure.

本研究开发了一种微观力学启发的构成模型,用于描述玻璃态聚合物裂纹内纤维化材料在循环载荷作用下的变形行为。在有限应变设置下,该模型解释了材料从完整的块状聚合物拉伸成裂纹纤维以及从原始纤维过渡到成熟纤维所发生的形态变化。在以往研究的基础上,纤维拉伸被描述为一种粘塑性过程。本研究的一个新贡献是根据实验观察结果,将现有纤维的粘弹性变形纳入其中。这一新观点允许蠕变恢复,尤其是在循环变形的卸载阶段。参数研究特别关注纤维拉伸和纤维蠕变的特征时间尺度与施加的加载速率之间的关系,说明了模型的性能。由于该模型是作为玻璃态聚合物内聚断裂模拟的输入而设计的,因此对其在单调加载下的响应进行了分析,并与现有的龟裂模型进行了比较。然而,最令人感兴趣的是模型在循环加载下的行为,研究了不同加载情况下直至纤维断裂的情况。研究强调了两种粘性机制之间复杂的相互作用,以及它们如何影响裂纹物质的局部变形行为和直至失效的循环次数。


Thin-Walled Structures

Nonlinear vibration analysis of double curved shallow sandwich shell in which the core made of three-phase nanocomposite and the two-outer layer of electromagnetic materials

Nguyen Van Huong, Pham Hong Cong, Nguyen Dinh Duc

doi:10.1016/j.tws.2023.111501

以三相纳米复合材料为内核、两外层为电磁材料的双曲面浅夹层壳体的非线性振动分析

This paper investigates the nonlinear vibrations of a double curved shallow sandwich shell with a three-phase nanocomposite core and two outer electromagnetic layers considering the thermal environment's influence. Relying on the Halpin-Tsai model, the core is assumed to be made of some composite plies incorporating three constituents: carbon nanotubes (CNTs) or graphene nanoplatelets (GPLs) as nanocomposites, fibers and polymeric matrix (resin). Governing equations calculating the nonlinear vibration of the double curved shallow shell were obtained by combining Reddy's first-order shear deformation theory (FSDT) and the Von Kármán geometrical nonlinearity. Later, this system of equations is transformed into the nonlinear ordinary differential expressions by utilizing the Galerkin procedure. Thus, the effects of material properties, temperature, geometrical properties, elastic foundations to the frequency of linear and nonlinear free vibration, and amplitude-frequency relations of the double curved shallow sandwich shell were discussed. The results demonstrate that the free vibration frequency of the shell increases if the magnetic field enhances, whereas that decreases when the voltage expands in both models as CNTs and GPLs. Simultaneously, the shallow shell has a better ability to force load compared to a plate with the same dimensions. These outcomes can make a profit in the design and manufacturing of new smart structures applied in energy harvesting, and medicine.

考虑到热环境的影响,本文研究了具有三相纳米复合材料内核和两个电磁外层的双曲面浅夹层壳体的非线性振动。根据 Halpin-Tsai 模型,假定核心由一些复合材料层组成,其中包含三种成分:作为纳米复合材料的碳纳米管 (CNT)或石墨烯纳米片 (GPL)、纤维和聚合物基质(树脂)。通过结合 Reddy 的一阶剪切变形理论(FSDT)和 Von Kármán 几何非线性,得到了计算双曲面浅壳非线性振动的指导方程。随后,利用 Galerkin 程序将该方程系统转化为非线性常微分表达式。因此,讨论了材料特性、温度、几何特性、弹性基础对双曲面浅夹层壳的线性和非线性自由振动频率以及幅频关系的影响。结果表明,在 CNTs 和 GPLs 两种模型中,如果磁场增强,壳体的自由振动频率会增加,而当电压扩大时,自由振动频率会降低。同时,与相同尺寸的板相比,浅壳的受力能力更强。这些成果将有助于设计和制造应用于能量收集和医学领域的新型智能结构。


Stress-strain state of a porous flexible rectangular FGM size-dependent plate subjected to different types of transverse loading: Analysis and numerical solution using several alternative methods.

A.V. Krysko, L.A. Kalutsky, V.A. Krysko

doi:10.1016/j.tws.2023.111512

多孔柔性矩形 FGM 尺寸依赖板在不同类型横向荷载作用下的应力-应变状态:使用几种替代方法进行分析和数值求解。

In this study, a mathematical model of flexible porous functionally graded (PFG) Kirchhoff size-dependent plates on a rectangular plane is constructed. Hamilton's principle provides new size-dependent governing equations, taking into account geometrical nonlinearity according to the model of Theodor von Kármán, as well as boundary conditions and initial conditions for the displacement of the plates. Modified Coupled Stress Theory (MCST) is used to account for size-dependent effects. Numerical investigations analysing the stress-strain state of flexible Kirchhoff functionally graded size-dependent porous plates on a rectangular plane are based on the application of the Variational Iteration Method (VIM) or the Extended Kantorovich Method (EKM). The efficiency and high accuracy of the VIM method are demonstrated. The validity and reliability of the solutions obtained by VIM are discussed and compared with solutions obtained by other methods, such as the BGM in higher approximations, FDM of second-order accuracy and the FEM. Additionally, the solutions are compared with results obtained by other authors in the study of porous functionally graded macro, micro, and nanoplates. The solutions obtained are considered accurate. The results include an analysis of the influence of size-dependent parameters, type of material porosity, porosity index, functionally graded index, and different types of boundary conditions on the stress-strain state of plates under the action of different types of transverse loading.

本研究构建了矩形平面上柔性多孔功能分层(PFG)基尔霍夫尺寸相关板的数学模型。根据 Theodor von Kármán 模型,考虑到几何非线性,以及板位移的边界条件和初始条件,汉密尔顿原理提供了新的尺寸相关控制方程。修正耦合应力理论(MCST)用于考虑尺寸效应。应用变异迭代法(VIM)或扩展 Kantorovich 法(EKM)对矩形平面上柔性基尔霍夫功能分级多孔板的应力应变状态进行了数值研究分析。结果证明了 VIM 方法的高效性和高精确度。讨论了 VIM 求解的有效性和可靠性,并将其与其他方法求解进行了比较,如更高近似的 BGM、二阶精度的 FDM 和 FEM。此外,还将求解结果与其他作者在多孔功能分级宏观、微观和纳米板研究中获得的结果进行了比较。所获得的解决方案被认为是精确的。研究结果包括分析尺寸相关参数、材料孔隙率类型、孔隙率指数、功能分级指数以及不同类型的边界条件对不同类型横向载荷作用下板材应力应变状态的影响。


Energy-based efficient residual stress prediction of titanium alloys with lack-of-fusion porosity in powder bed fusion

Zhi-Jian Li, Hong-Liang Dai, Chong Du, Peng Xiao, Yuan Yao

doi:10.1016/j.tws.2023.111513

基于能量的粉末床熔合中具有熔合孔隙率不足的钛合金的高效残余应力预测

Residual stress and porosity exert adverse effects on the mechanical properties of metal parts fabricated by powder bed fusion. However, the modeling of the correlation between process parameters, process-induced porosity, and residual stress remains challenging. In this paper, a thermo-mechanical model of titanium alloy with porosity is established, where the relation between process parameters, porosity, and effective material properties is identified. The porosity is first predicted based on the power conservation principle in the process. The effective material properties of as-built titanium alloy with porosity are estimated using a homogenization method. Subsequently, the stress and distortion resulting from temperature variation are predicted using the shear deformation theory. The predicted results exhibit excellent agreement with the predictions and experimental results in the literature. Furthermore, the effect of the main process parameters on the porosity, residual stress, and distortion is investigated. The results show that excessive laser power, small laser radii, and extensive scan tracks contribute to a significant lack-of-fusion porosity. Additionally, the normal stress along the scan direction and vertical deflection are the major residual stress and distortion of titanium alloy with porosity, respectively. The proposed model can serve as a guideline for the design and fabrication of PBF-built titanium alloys.

残余应力和孔隙率对通过粉末床熔融技术制造的金属零件的机械性能产生不利影响。然而,工艺参数、工艺引起的孔隙率和残余应力之间的相关性建模仍具有挑战性。本文建立了具有孔隙率的钛合金热机械模型,确定了工艺参数、孔隙率和有效材料性能之间的关系。首先根据工艺中的功率守恒原理预测孔隙率。使用均质化方法估算出带孔隙率钛合金的有效材料属性。随后,利用剪切变形理论预测温度变化产生的应力和变形。预测结果与文献中的预测和实验结果非常吻合。此外,还研究了主要工艺参数对孔隙率、残余应力和变形的影响。结果表明,过大的激光功率、过小的激光半径和过长的扫描轨迹都会造成严重的熔合孔隙率不足。此外,沿扫描方向的法向应力和垂直挠度分别是产生气孔的钛合金的主要残余应力和变形。所提出的模型可作为设计和制造 PBF 型钛合金的指南。


Dynamic response of square sandwich panels with stagger-layered honeycomb cores under intensive near-field air blast loading

Ying Liu, Haichao Yu, Jinda Wu, Kui Tang

doi:10.1016/j.tws.2023.111515

带有交错层蜂窝芯的方形夹芯板在高强度近场空气冲击载荷下的动态响应

Metallic honeycomb sandwich panels have been widely used in energy dissipation due to large plastic deformation under impact/blast loading. In this paper, the dynamic response of a honeycomb sandwich panel with stagger-layered core under intensive near-field air blast loading is investigated. Comparative experiments are conducted for stagger-layered and typical honeycomb sandwich panels with the same geometrical size and mass. Numerical simulation has been undertaken based on the experiments. Numerical results coincide well with experimental results on the deformation/failure modes and center-point deflection of back face sheet. The influence of layer number as well as the geometrical parameters on the energy absorption ability of sandwich panels is clarified. Results show that stagger-layer arrangement of honeycomb core greatly improves energy dissipation capability of sandwich panels compared to typical one with the same mass. The increase of layer number and cell size benefits this effect. These findings indicates that core stagger-layer arrangement is a well choice to improve energy dissipation ability of sandwich panels under air blast loading, especially for highly intensive near-field blast loading.

金属蜂窝夹芯板在冲击/爆破载荷作用下会产生较大的塑性变形,因此被广泛应用于消能领域。本文研究了带有错层夹芯的蜂窝夹芯板在高强度近场空气冲击载荷下的动态响应。对具有相同几何尺寸和质量的交错层和典型蜂窝夹芯板进行了对比实验。在实验的基础上进行了数值模拟。数值结果与实验结果在背面板材的变形/失效模式和中心点挠度方面非常吻合。层数和几何参数对夹芯板能量吸收能力的影响也得到了澄清。结果表明,与相同质量的典型夹芯板相比,蜂窝芯的错层布置大大提高了夹芯板的能量耗散能力。层数和单元尺寸的增加对这一效果有利。这些研究结果表明,蜂窝芯错层布置是提高夹芯板在空气冲击载荷下能量耗散能力的最佳选择,尤其是在高强度近场冲击载荷下。


Test on Seismic Behaviors of Stainless Steel Bolted Extended End-Plate Beam-column Joints

Baofeng Zheng, Dianhan Wu, Jiachang Wang, Ganping Shu

doi:10.1016/j.tws.2023.111516

不锈钢螺栓加长端板梁柱连接的抗震性能测试

This study conducted tests on the seismic behavior of austenitic stainless steel bolted extended end-plate beam-column joints, which have been few reported. Considering the influence of material type, end-plate thickness, bolt diameter, panel zone thickness, and loading scheme, 11 stainless steel joints and two carbon steel joints were designed and tested. Material properties, joint failure modes, moment-rotation curves, bolt load distributions, and joint component yield sequences were reported in detail. Experimental research showed that the beam-column joints in austenitic stainless steel experienced four failure modes, i.e. plastic hinge at the beam end, fracture failure of weld between the beam flange and end-plate, bolt rupture failure, and composite failure. All the tested joints had good seismic behavior, with rotation capacity greater than 0.03 rad.. The influence of joint configurations on the seismic behavior were analyzed. The results indicated that the end-plate thickness, end-plate stiffener, and bolt diameter had a substantial impact on the joint seismic behavior, while the thickness of column web in panel zone, material properties, and loading scheme had a comparatively small effect. The initial rotational stiffness and moment resistance(yield moment) of joint obtained from the experiment were compared with the predictions of the EN1993-1-8, Design Guide 16, and JGJ 82-2011. Comparisons indicated that the EN1993-1-8 overestimated the initial rotational stiffness; Both the EN1993-1-8 and JGJ 82-2011 underestimated the moment resistance, while the predictions from the Design Guide 16 were significantly higher than the moment resistance and closer to the ultimate moment.

本研究对奥氏体不锈钢螺栓连接加长端板梁柱接头的抗震行为进行了测试,目前相关报道较少。考虑到材料类型、端板厚度、螺栓直径、面板区厚度和加载方案的影响,设计并测试了 11 个不锈钢接头和 2 个碳钢接头。详细报告了材料特性、连接失效模式、力矩-旋转曲线、螺栓载荷分布以及连接部件屈服序列。实验研究表明,奥氏体不锈钢梁柱接头经历了四种失效模式,即梁端塑性铰链、梁翼缘板和端板之间焊缝断裂失效、螺栓断裂失效和复合失效。所有测试接头都具有良好的抗震性能,旋转能力大于 0.03 弧度。分析了接头结构对抗震性能的影响。结果表明,端板厚度、端板加劲件和螺栓直径对接头抗震性能有很大影响,而面板区柱腹板厚度、材料特性和加载方案的影响相对较小。实验得出的连接初始旋转刚度和抗弯矩(屈服弯矩)与 EN1993-1-8、Design Guide 16 和 JGJ 82-2011 的预测值进行了比较。比较结果表明,EN1993-1-8 高估了初始旋转刚度;EN1993-1-8 和 JGJ 82-2011 低估了抗弯强度,而《设计指南 16》的预测值明显高于抗弯强度,且更接近极限弯矩。


The low frequency multi-linear spectrum vibration control study of cylindrical shell through a semi-analytical method

Yuan Du, Yang Tang, Yucheng Zou, Yichun Wang, Fuzhen Pang, Fuxin Jia, Yong Ma, Shijie Wang

doi:10.1016/j.tws.2023.111521

通过半解析法研究圆柱形壳体的低频多线性频谱振动控制

Dynamic vibration absorber is efficient in controlling low frequency vibration of cylindrical shell, which is meaningful for engineering practice. However, the efficiency of designing dynamic vibration absorber using traditional method is low. This paper demonstrates a semi-analytical method for designing dynamic vibration absorber of cylindrical shell. The convergence analysis presented in the research proves the accuracy of the current method when handling different edge constraints through limited truncation numbers. Additionaly, forced vibration and control of multi-line spectrum vibration of cylindrical shell have also been studied. The comparison between FEM and current method shows a significant improvement when handling equivalent mass, which is a key process when designing dynamic vibration absorbers. Finally, an intriguing relationship is discovered when controlling multiple resonance peaks through a single dynamic vibration absorber. The semi-analytical method described in this paper may be beneficial when controlling the vibration of cylindrical shell structures in the further research.

动态吸振器能有效控制圆柱形壳体的低频振动,对工程实践很有意义。然而,使用传统方法设计动态吸振器的效率较低。本文展示了一种设计圆柱形壳体动态吸振器的半解析方法。研究中的收敛分析证明了当前方法在通过有限截断数处理不同边缘约束时的准确性。此外,还研究了圆柱形壳体的强迫振动和多线谱振动控制。在处理等效质量时,有限元与当前方法的比较显示了显著的改进,而等效质量是设计动态减震器的关键过程。最后,在通过单个动态吸振器控制多个共振峰时,发现了一种有趣的关系。本文所述的半分析方法可能会在进一步的研究中有益于控制圆柱形壳体结构的振动。


A novel active hydroforming & curing process to manufacture GLARE laminates: Numerical and experimental investigations

Meng Zhang, Muhammad Saad, Hang Zheng, Marko Vilotic, Bao-sheng Liu, Zheng-ping Zou, Yong Li

doi:10.1016/j.tws.2023.111508

制造 GLARE 层压板的新型主动水压成型和固化工艺:数值和实验研究

Fiber Metal Laminates (FMLs) are preferable thin-walled structures in several fields for their exceptional mechanical properties. However, how to manufacture thin-walled FMLs structures with complex shapes and guarantee the high mechanical properties is still a challenge. To address these, this paper proposes an innovative hybrid forming method, referred to as active warm hydroforming and curing, to enhance the formability and performance of FMLs in GLARE form by combining the forming and curing process into a single step. The hybrid method was verified on a box-shaped part as a proof-of-concept to assess the feasibility and parameter influence. Online curing was utilized to enhance efficiency and quality. The outcomes revealed that the new method increases the ultimate tensile stress by 12.1 % and reduces curing deformation from 3.1 mm to 1.3 mm compared to the vacuum bagging method. Furthermore, the critical parameters in forming of thin-walled structures, including blank holder force (BHF), pressure rate (PR), maximum pressure (MP), and forming temperature (FT), were identified using experimental, mathematical, and numerical approaches. Four defects in the formed thin-walled structures were observed and successfully eliminated through the control of these parameters. The method and results presented in this paper also provide direct guidance for optimizing the process parameters of FMLs warm hydroforming.

金属纤维层压板(FMLs)因其优异的机械性能而成为多个领域的首选薄壁结构。然而,如何制造形状复杂的薄壁 FMLs 结构并保证其较高的机械性能仍是一项挑战。为了解决这些问题,本文提出了一种创新的混合成型方法,即主动温压成型和固化,通过将成型和固化过程合并为一个步骤来提高 GLARE 形式 FML 的成型性和性能。作为概念验证,该混合方法在箱形零件上进行了验证,以评估其可行性和参数影响。在线固化被用来提高效率和质量。结果表明,与真空袋法相比,新方法的极限拉伸应力提高了 12.1%,固化变形从 3.1 mm 减小到 1.3 mm。此外,利用实验、数学和数值方法确定了薄壁结构成型的关键参数,包括坯料夹持力(BHF)、压力速率(PR)、最大压力(MP)和成型温度(FT)。通过对这些参数的控制,观察到并成功消除了成形薄壁结构中的四个缺陷。本文介绍的方法和结果也为优化 FML 温水压成形工艺参数提供了直接指导。


Out-of-plane Compressive Response of Aluminum Honeycomb Sandwich Panels: Adhesive Geometry and Bonding Effects

Mengqian Sun, Patrick Kendall, Diane Wowk, Christopher Mechefske, Il Yong Kim

doi:10.1016/j.tws.2023.111509

铝蜂窝夹芯板的平面外压缩响应:粘合剂几何形状和粘合效果

Lightweight aluminum honeycomb sandwich panels are widely used in industrial engineering, particularly in aircraft applications. Due to their thin-walled nature, the honeycomb cell walls are especially susceptible to buckling under out-of-plane compressive loading, while the adhesive fillet that secures the honeycomb to the face-sheet remains intact. This paper investigates the effect of the adhesive geometry and bonding constraints on the out-of-plane compressive response through experimental, Finite Element (FE), and mathematical methods. A hybrid method accounting for adhesive bonding between the face-sheet and the cell walls, and different adhesive fillet geometries was proposed to predict strain onset and stress-strain relationships during densification. The resulting stress-strain curves predicted the energy absorbed by the panels to within 3.5% of the experimental results. The widely used material model for honeycomb core does not account for densification and underpredicted the absorbed energy by 15.6%. These findings emphasize the need for detailed adhesive analysis in the design of lightweight, thin-walled sandwich structures.

轻质铝蜂窝夹层板广泛应用于工业工程,尤其是飞机应用领域。由于其薄壁特性,蜂窝单元壁特别容易在平面外压缩载荷作用下发生屈曲,而将蜂窝固定到面板上的粘合剂丝扣却保持完好。本文通过实验、有限元(FE)和数学方法研究了粘合剂几何形状和粘合约束对平面外压缩响应的影响。我们提出了一种混合方法来预测致密化过程中的应变起始和应力-应变关系,该方法考虑到了面层和细胞壁之间的粘合以及不同的粘合剂圆角几何形状。由此得出的应力-应变曲线预测了面板吸收的能量,与实验结果的误差不超过 3.5%。广泛使用的蜂窝芯材料模型没有考虑到致密化,对吸收能量的预测低了 15.6%。这些发现强调了在设计轻质薄壁夹层结构时进行详细粘合分析的必要性。


BENDING ANALYSIS OF FGSP NANOPLATE RESTING ON ELASTIC FOUNDATION BY USING NONLOCAL QUASI-3D THEORY

Dang Xuan Hung, Le Tien Thinh, Nguyen Văn Long, Tran Minh Tu, Dang Xuan Trung

doi:10.1016/j.tws.2023.111510

利用非局部准三维理论对位于弹性地基上的 fgsp 纳米板进行弯曲分析

In this paper, the bending response of a functionally graded saturated porous (FGSP) nanoplate resting on the Pasternak elastic foundation is analyzed within the framework of quasi-3D higher-order shear deformation theory (quasi-3D HSDT) for the first time. The material properties are presumed to change gradually along the thickness direction following three patterns of porosity distribution: uniform, non-uniform symmetric, and asymmetric. The theory of poroelasticity developed by Biot is utilized in modeling the stress-strain relationships for the saturated condition. Moreover, the nanoscale effects of the structures are considered by Eringen's nonlocal elasticity theory. The governing equations are derived by using the principle of minimum potential energy according to quasi-3D HSDT, which ensures transverse shear stress-free on the upper and lower surfaces of the nanoplate. Based on the obtained closed-form solution, the impacts of the porosity distribution patterns, porosity coefficient, Skempton coefficient, geometrical parameters, elastic foundation, and nonlocal parameters on the bending behavior have been explored. According to the findings, when the pores are saturated by the fluid, the plate stiffness increases. Additionally, increasing the values of the nonlocal parameter for FGSP nanoplates leads to an increase in deflection and stresses. Finally, the present study quantitatively reveals the size-dependent effects of a saturated porous medium.

本文首次在准三维高阶剪切形变理论(quasi-3D HSDT)框架内分析了位于帕斯捷尔纳克弹性基础上的功能分级饱和多孔(FGSP)纳米板的弯曲响应。假定材料特性沿厚度方向按照均匀、非均匀对称和非对称三种孔隙率分布模式逐渐变化。在模拟饱和状态下的应力-应变关系时,采用了 Biot 提出的孔弹性理论。此外,Eringen 的非局部弹性理论还考虑了结构的纳米级效应。利用准三维 HSDT 的最小势能原理推导出控制方程,确保纳米板上下表面无横向剪应力。根据得到的闭式解,探讨了孔隙率分布模式、孔隙率系数、Skempton 系数、几何参数、弹性基础和非局部参数对弯曲行为的影响。研究结果表明,当孔隙被流体饱和时,板的刚度会增加。此外,增加 FGSP 纳米板的非局部参数值会导致挠度和应力增加。最后,本研究定量揭示了饱和多孔介质的尺寸效应。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemInspireMAGNET振动断裂复合材料非线性化学多孔介质裂纹理论材料螺栓
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【新文速递】2023年12月11日复合材料SCI期刊最新文章

今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Science and Technology 4 篇Composite StructuresA progressive damage model associated with dynamic fracture toughness and IFF criterion with a fast search algorithm of fracture angleZhuo Zhang, Kai Zhang, Bailin Zhengdoi:10.1016/j.compstruct.2023.117802与动态断裂韧性和 IFF 准则相关的渐进损伤模型,以及断裂角快速搜索算法This paper presents a quick search algorithm of the fracture angle of inter-fiber fracture (IFF) criterion and a progressive damage model considering the dynamic fracture toughness effect. The fracture angle determination of the IFF criterion is necessary and time-consuming, which has limited its practicality. Therefore, to accurately calculate stress exposure factors under various combinations of stress states, a highly efficient algorithm is needed. In this paper, a novel algorithm using stress tractions on the fracture plane and the golden section search (GSS) is promoted. Through a series of simulation tests, this novel algorithm has been proven to be exact and efficient compared with other two common algorithms, which saves an average of 63.2% and 28.1% of the time in 1 million calculations and 2 h 2 min 4 sec and 39 min 2 sec in simulations. Additionally, fracture toughness, which controls material damage evolution process, also has strain-rate effect like elastic modulus and strength. Hence, a new progressive damage model considering the dynamic fracture toughness effect is proposed. The results of dynamic compression and ballistic impact tests and simulations demonstrate the fidelity of the novel damage model.本文提出了一种纤维间断裂(IFF)准则断裂角的快速搜索算法和一种考虑到动态断裂韧性效应的渐进损伤模型。纤维间断裂(IFF)准则的断裂角测定既必要又耗时,这限制了其实用性。因此,要准确计算各种应力状态组合下的应力暴露因子,需要一种高效的算法。本文提出了一种利用断裂面上的应力牵引和黄金分割搜索(GSS)的新型算法。通过一系列模拟测试,证明这种新型算法与其他两种常用算法相比,精确高效,在 100 万次计算和 2 小时 2 分 4 秒和 39 分钟 2 秒的模拟中,平均分别节省了 63.2% 和 28.1% 的时间。此外,控制材料损伤演变过程的断裂韧性与弹性模量和强度一样,也具有应变速率效应。因此,提出了一种考虑动态断裂韧性效应的新的渐进损伤模型。动态压缩和弹道冲击试验及模拟结果表明了新型损伤模型的真实性。Composites Part A: Applied Science and ManufacturingOn the understanding of bubble dynamics through a calibrated textile-like porous medium using a machine learning based algorithmJoão Machado, Masoud Bodaghi, Mostafa Nikzad, Pedro P. Camanho, Suresh Advani, Nuno Correiadoi:10.1016/j.compositesa.2023.107955利用基于机器学习的算法了解气泡在经过校准的类纺织多孔介质中的动力学特性In this work, we present a proof of concept for both 3D-printed media and a machine learning analysis methodology to investigate void formation and transport during liquid filling. Through a series of experiments, we characterized void formation and transport at constant flow rates using two calibrated fabric-like porous geometries created by Stereolithography and Multi Jet Fusion 3D printing techniques. Our findings highlight the significance of porous medium geometry and void size, in addition to the capillary number, in characterizing void formation and mobility during resin flow into a mold containing a fibrous preform. Notably, the paper's strength lies in the presentation of advanced bubble analysis methods, including frame-by-frame high-resolution video analysis, enabling the identification of individual bubbles and the extraction of their statistics, such as count, size, and velocity throughout the experiment. These insights contribute to the design of more efficient processes, resulting in composite parts with reduced void content.在这项工作中,我们提出了一种三维打印介质的概念验证和机器学习分析方法,用于研究液体填充过程中的空隙形成和传输。通过一系列实验,我们利用立体光刻和多喷射融合三维打印技术创建的两种校准织物状多孔几何形状,对恒定流速下的空隙形成和传输进行了表征。我们的研究结果凸显了多孔介质几何形状和空隙大小以及毛细管数量在表征树脂流入含有纤维预型件的模具过程中空隙形成和流动性方面的重要性。值得注意的是,论文的优势在于介绍了先进的气泡分析方法,包括逐帧高分辨率视频分析,从而能够识别单个气泡并提取其统计数据,如整个实验过程中的数量、大小和速度。这些见解有助于设计更高效的工艺,从而减少复合材料部件的空隙含量。Ultrastretchable and adhesive MXene-based hydrogel for high-performance strain sensing and self-powered applicationWei Zhang, Pei-Lin Wang, Xing-Xiang Ji, Ling-Zhi Huang, Da-Qi Cao, Junfeng Li, Ming-Guo Madoi:10.1016/j.compositesa.2023.107957 用于高性能应变传感和自供电应用的超拉伸和粘性 MXene 基水凝胶Conductive hydrogels have been extensively explored for human movement and health monitoring. However, the poor adhesion of hydrogels to the skin hinders their performance in real-time monitoring with minimal loss of signal transmission. In this work, hydrogels composed of acrylic acid (AA), acrylic acid–N-hydrosuccinimide ester (AA–NHS), sulfobetaine methacrylate (SBMA), and cellulose nanofibers (CNFs) in the presence of initiators were rapidly gelated (within a few minutes) after adding Ti3C2TX MXene as a versatile crosslinking agent. AA and SBMA copolymerized to form the main network structure of the hydrogel and the introduced CNF improved the tensile strain of the hydrogels from 1737% to 2240%. By virtue of the combined zwitterionic-adhesion mechanism and NHS-activated ester bonds, the hydrogels conformally adhered to porcine skin with an adhesive strength of 11.6 kPa. When assembled as strain sensors, the hydrogel sensors exhibited high sensitivity (gauge factor = 4.98) and a fast response (95 ms). Next, the hydrogel was assembled as the electrode in a triboelectric nanogenerator (TENG) for mechanical-energy harvesting and self-powered sensing. The TENG exhibited good electrical output properties and could charge commercial capacitors with the mechanical energy harvested from walking. This work promises the design of wearable hydrogel devices with mechanical extensibility and self-adhesive properties.导电水凝胶已被广泛用于人体运动和健康监测。然而,水凝胶与皮肤的粘附性较差,这阻碍了其在实时监测中实现最小信号传输损失的性能。在这项研究中,由丙烯酸(AA)、丙烯酸-N-氢琥珀酰亚胺酯(AA-NHS)、甲基丙烯酸磺基甜菜碱(SBMA)和纤维素纳米纤维(CNFs)组成的水凝胶在加入作为多功能交联剂的 Ti3C2TX MXene 后,在引发剂的存在下(几分钟内)迅速凝胶化。AA 和 SBMA 共聚形成了水凝胶的主要网络结构,引入的 CNF 将水凝胶的拉伸应变从 1737% 提高到 2240%。凭借齐聚物粘附机制和 NHS 激活的酯键,水凝胶与猪皮肤贴合粘附,粘附强度达到 11.6 千帕。当组装成应变传感器时,水凝胶传感器表现出高灵敏度(测量系数 = 4.98)和快速响应(95 毫秒)。接着,水凝胶被组装成三电纳米发电机(TENG)的电极,用于机械能收集和自供电传感。该 TENG 具有良好的电输出特性,并能利用从行走中收集的机械能为商用电容器充电。这项研究有望设计出具有机械延伸性和自粘性的可穿戴水凝胶设备。Composites Science and TechnologyMode I fracture toughness with fiber bridging of unidirectional composite laminates under cryogenic temperatureJinxin Meng, Hongshuai Lei, Yuanchen Li, Yunlong Ma, Heng Yang, Panding Wang, Daining Fangdoi:10.1016/j.compscitech.2023.110386 低温条件下单向复合材料层压板纤维架桥的 I 型断裂韧性Carbon fiber reinforced polymer (CFRP) composites have widely been used in the aerospace field owing to their excellent mechanical properties. However, composite structures often fail under complex space environmental conditions. In particular, the fiber bridging and cryogenic temperature may greatly change the fracture toughness of CFRP composites. Herein, the effects of cryogenic temperature and fiber bridging on the fracture toughness of unidirectional composite laminates were experimentally examined by double cantilever beam (DCB) testing at different temperatures (room temperature, −50 °C, −70 °C, −100 °C, −150 °C, and −180 °C). Different calculation methods of fracture toughness were used and the results were compared. A method without measuring the delamination length at low temperatures was used and the results were consistent with other methods. The average difference in fracture toughness values was less than 5 %. The fiber-bridging microstructures of composites under cryogenic temperatures were examined by confocal microscopy along with the geometric morphology and parameters of surface roughness. The results suggested changes in the matrix failure mechanism at −50 °C, resulting in maximum fracture toughness, which is 26.45 % higher than that at room temperature. A semi-analytic approach was then proposed to express the bridge stress, and a bilinear cohesive zone model was established to simulate the delamination of composite laminates at low temperatures. Overall, the numerical data agreed well with the experimental results (peak force maximum error of 17 %), suggesting the usefulness of the proposed method for the prediction of interlamination properties and structural damage design of composite structures at cryogenic temperature.碳纤维增强聚合物(CFRP)复合材料因其优异的机械性能而被广泛应用于航空航天领域。然而,复合材料结构经常会在复杂的太空环境条件下失效。其中,纤维架桥和低温会极大地改变 CFRP 复合材料的断裂韧性。本文通过不同温度(室温、-50 °C、-70 °C、-100 °C、-150 °C和-180 °C)下的双悬臂梁(DCB)测试,实验研究了低温和纤维架桥对单向复合材料层压板断裂韧性的影响。采用了不同的断裂韧性计算方法,并对结果进行了比较。使用了一种在低温下不测量分层长度的方法,结果与其他方法一致。断裂韧性值的平均差异小于 5%。共聚焦显微镜检查了低温条件下复合材料的纤维桥接微结构以及几何形态和表面粗糙度参数。结果表明,在-50 °C时基体破坏机制发生了变化,导致断裂韧性达到最大值,比室温下的断裂韧性高出26.45%。随后提出了一种半解析方法来表达桥应力,并建立了双线性内聚区模型来模拟复合材料层压板在低温下的分层。总体而言,数值数据与实验结果吻合良好(峰值力最大误差为 17%),表明所提出的方法可用于预测低温下复合材料结构的层间特性和结构损伤设计。Experimental and simulation analysis of the effect of GNPs on the mechanical and interfacial properties of CF/PEEK-Ti fiber metal laminatesMeng Cao, Shuo Wang, Jian Zang, Mingyu Liu, Changjiang Qian, Yewei Zhang, Di Nadoi:10.1016/j.compscitech.2023.110387 GNPs 对 CF/PEEK-Ti 纤维金属层压板机械性能和界面性能影响的实验和模拟分析In this study, graphene nanoplatelets (GNPs) were used to improve the interfacial and mechanical properties of carbon fibre-reinforced polyetheretherketone-based titanium alloy laminates (CF/PEEK-Ti) and molecular dynamics (MD) simulations were used to investigate the mechanism by which GNPs improve CF/PEEK-Ti, collectively known as fibre reinforced metal laminates (FMLs). In addition, surface anodising of titanium (Ti) sheets was used further to enhance the interfacial bonding properties of the FMLs. The experimental results showed that the flexural and shear strengths of the anodised FMLs were increased by 77.7% and 29.5%, respectively, compared with those of the Ti plates without surface anodisation. Based on this, different levels (0–1.5 wt%) of GNPs were added to the FMLs matrix, and test results showed that FMLs containing 0.5 wt% GNPs had the best flexural and shear strengths, 108.9% and 130.8% higher than untreated FMLs without GNPs. In addition, an in-depth microscopic analysis was carried out to understand the enhancement mechanism of GNPs on FMLs. Finally, MD simulations were used to analyze the role and mechanism of GNPs in this system. The results show that the addition of GNPs can increase the interfacial energy of FMLs. In other words, the interfacial mechanical properties of FMLs are improved. The effect of the dispersion of GNPs on the interfacial properties of FMLs was also investigated. The polyetheretherketone (PEEK) matrix could be significantly improved by well-dispersed GNPs. These findings provide insight into designing high-performing composites for various engineering applications.本研究利用石墨烯纳米片(GNPs)改善了碳纤维增强聚醚醚酮基钛合金层压板(CF/PEEK-Ti)的界面和机械性能,并利用分子动力学(MD)模拟研究了 GNPs 改善 CF/PEEK-Ti (统称为纤维增强金属层压板(FMLs))的机理。此外,还对钛(Ti)片进行了表面阳极氧化处理,以进一步提高 FML 的界面结合性能。实验结果表明,与未进行表面阳极氧化处理的钛板相比,经过阳极氧化处理的 FML 的抗弯强度和抗剪强度分别提高了 77.7% 和 29.5%。在此基础上,在 FMLs 基体中添加了不同含量(0-1.5 wt%)的 GNPs,测试结果表明,含有 0.5 wt% GNPs 的 FMLs 的抗弯强度和抗剪强度最好,分别比未添加 GNPs 的 FMLs 高出 108.9% 和 130.8%。此外,还进行了深入的显微分析,以了解 GNPs 对 FML 的增强机制。最后,利用 MD 模拟分析了 GNPs 在该体系中的作用和机制。结果表明,GNPs 的加入可以增加 FMLs 的界面能。换言之,FML 的界面力学性能得到了改善。此外,还研究了 GNPs 的分散对 FMLs 的界面性能的影响。分散良好的 GNPs 能显著改善聚醚醚酮(PEEK)基体的性能。这些发现为设计各种工程应用的高性能复合材料提供了启示。An embedded digital element model to simulate the wrinkle defects driven by the consolidation of compositesYongshan Li, Kai Liu, Guangchang Chen, Ge Jingran, Jing Yang, Xuefeng Li, Shuo Liu, Jun Liangdoi:10.1016/j.compscitech.2023.110389 模拟复合材料固结产生的皱纹缺陷的嵌入式数字元素模型Understanding the mechanisms of fiber wrinkling during the compaction process is of paramount importance as fiber wrinkling significantly affects the mechanical properties of composite materials. This study introduces an embedded digital element model for simulating the consolidation process of prepreg. Flexible digital element chains are employed to simulate the reinforcing effect of fibers on resin, accounting for the viscoelastic constitutive behavior of uncured resin. The simulation captures intra-layer wrinkles and in-plane waviness defects in the consolidated prepreg, thereby uncovering the mechanism behind fiber wrinkle formation during composite material prepreg consolidation. The accuracy of the model is validated through compression experiments on flat plates and L-shaped structures. The results demonstrate that the proposed embedded digital element model accurately predicts wrinkle defects. Factors such as interlayer friction of the prepreg, consolidation temperature, and mold curvature radius significantly influence the shape and size of wrinkles.由于纤维起皱会严重影响复合材料的机械性能,因此了解压实过程中纤维起皱的机理至关重要。本研究介绍了一种用于模拟预浸料固结过程的嵌入式数字元素模型。采用柔性数字元素链模拟纤维对树脂的增强作用,并考虑未固化树脂的粘弹性构成行为。模拟捕捉了固化预浸料中的层内皱纹和平面波状缺陷,从而揭示了复合材料预浸料固化过程中纤维皱纹形成的机理。通过对平板和 L 型结构进行压缩实验,验证了模型的准确性。结果表明,所提出的嵌入式数字元素模型能准确预测皱纹缺陷。预浸料的层间摩擦力、固结温度和模具曲率半径等因素对皱纹的形状和大小有显著影响。Micromechanical characterization of Carbon/PEEK thermoplastic composite material in-situ consolidated by automated fiber placement: Stiffness predictionEmad Pourahmadi, Rajamohan Ganesan, Farjad Shadmehridoi:10.1016/j.compscitech.2023.110390 通过自动放置纤维对原位加固的碳/PEEK 热塑性复合材料进行微观力学表征:刚度预测Despite manufacturing challenges, Automated Fiber Placement (AFP) offers a viable alternative to conventional manufacturing methods, allowing for time and cost savings. Creating a Representative Volume Element (RVE) that realistically represents long-fiber-reinforced composites with high fiber volume fraction is a challenging task in modeling their response. The present research aims to predict effective stiffness properties of in-situ-consolidated Carbon/PEEK thermoplastic composite material by considering the effect of fiber volume fraction, void content, degree of crystallinity, and interlaminar resin pocket resulting from AFP in-situ consolidation manufacturing process. In this regard, two sets of samples were manufactured by AFP in-situ consolidation and autoclave re-consolidation methods. Both of them were evaluated by micrographic study and thermoanalytical Differential Scanning Calorimetry (DSC) technique to obtain inputs required for micromechanical analysis. The 2D RVEs on a micro-scale are developed to predict the transverse elastic modulus, out-of-plane Poisson's ratio and out-of-plane shear modulus of the composite material by applying Periodic Boundary Conditions (PBCs) and using Asymptotic Homogenization Theory (AHT). Results show that AFP in-situ consolidation may lead the transverse elastic and out-of-plane shear moduli of Carbon/PEEK thermoplastic composite material to be reduced by about 10 % and 20 %, respectively, compared to autoclave re-consolidation whereas the out-of-plane Poisson's ratio remains unchanged. The findings of the present work confirm that the mechanical performance of Carbon/PEEK thermoplastic composite material could be remarkably influenced by AFP in-situ consolidation manufacturing process, particularly in the transverse direction, which must be taken into account in finite element modeling, analyses, and design of AFP-manufactured composite laminates and structures.尽管在制造方面存在挑战,但自动纤维铺放技术(AFP)为传统制造方法提供了一种可行的替代方法,可以节省时间和成本。创建一个能真实再现高纤维体积分数的长纤维增强复合材料的代表体积元素(RVE)是对其响应建模的一项具有挑战性的任务。本研究旨在通过考虑纤维体积分数、空隙含量、结晶度和 AFP 原位固结制造过程中产生的层间树脂袋的影响,预测原位固结碳/PEEK 热塑性复合材料的有效刚度特性。为此,采用 AFP 原位固结法和高压釜再固结法制造了两组样品。通过显微照片研究和热分析差示扫描量热仪(DSC)技术对这两种方法进行了评估,以获得微观机械分析所需的输入数据。通过应用周期边界条件(PBC)和渐近均质化理论(AHT),开发了微尺度上的二维 RVE,以预测复合材料的横向弹性模量、面外泊松比和面外剪切模量。结果表明,与高压釜再固结相比,AFP 原位固结可使碳/PEEK 热塑性复合材料的横向弹性模量和平面外剪切模量分别降低约 10% 和 20%,而平面外泊松比保持不变。本研究结果证实,碳/PEEK 热塑性复合材料的机械性能会受到 AFP 原位固结制造工艺的显著影响,尤其是在横向方向上,这一点必须在 AFP 制造的复合材料层压板和结构的有限元建模、分析和设计中加以考虑。来源:复合材料力学仿真Composites FEM

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