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【新文速递】2024年1月14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,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 3 篇

International Journal of Solids and Structures

A three-dimensional micropolar beam model with application to the finite deformation analysis of hard-magnetic soft beams

Farzam Dadgar-Rad, Amirreza Hemmati, Mokarram Hossain

doi:10.1016/j.ijsolstr.2024.112662

三维微极梁模型及其在硬磁软梁有限变形分析中的应用

The main purpose of this contribution is to develop a three-dimensional (3D) nonlinear beam model based on the micropolar continuum theory. To do so, a kinematic model based on the deformation of three directors and accounting for the micro-rotation tensor of the micropolar theory is introduced. One of the main characteristics of the present beam model is that 3D constitutive equations without any modification can be directly used in the formulation. Furthermore, it is known that a body couple field is induced in hard-magnetic soft materials (HMSMs) when subjected to external magnetic fluxes. Therefore, the stress tensor in HMSMs is asymmetric, in general. Since the asymmetry of stress is one of the main features of the micropolar theory, the present formulation can be used for analyzing the deformation of beams made of HMSMs. Accordingly, the virtual external work of the present model is formulated so that it accounts for the contribution from uniform or constant-gradient external magnetic fluxes on the beam. Moreover, a Total Lagrangian (TL) nonlinear finite element (FE) formulation to provide numerical solutions of the related problems is developed. Several numerical examples are solved to investigate the capability of the developed formulation. It is shown that the present formulation can model the size-dependent behavior of beam-like structures if the material length-scale parameter of the micropolar constitutive model is comparable to the thickness of the beam. Moreover, the proposed model can successfully predict the finite deformation of 3D beams made of HMSMs subjected to magnetic loading.

本文的主要目的是建立基于微极连续统理论的三维(3D)非线性梁模型。为此,引入了一个基于三个方向的变形并考虑微极理论的微旋转张量的运动学模型。该梁模型的一个主要特点是无需任何修改即可直接使用三维本构方程。此外,已知硬磁软材料(HMSMs)在外加磁场作用下会产生体偶场。因此,在一般情况下,HMSMs中的应力张量是不对称的。由于应力的不对称性是微极理论的主要特征之一,因此本文的公式可以用于分析由微极材料制成的梁的变形。因此,本模型的虚外功可以考虑均匀或等梯度外磁通量对束流的贡献。此外,还建立了一个全拉格朗日(TL)非线性有限元(FE)公式,提供了相关问题的数值解。通过几个数值算例验证了所建立的公式的有效性。结果表明,如果微极性本构模型的材料长度尺度参数与梁的厚度相当,则该公式可以模拟类梁结构的尺寸依赖性行为。此外,所提出的模型可以成功地预测磁载荷作用下由hmsm制成的三维梁的有限变形。


Journal of the Mechanics and Physics of Solids

A new methodology for anisotropic yield surface description using model order reduction techniques and invariant neural network

Chady Ghnatios, Oana Cazacu, Benoit Revil-Baudard, Francisco Chinesta

doi:10.1016/j.jmps.2024.105542

基于模型降阶和不变神经网络的各向异性屈服面描述新方法

In this paper, we present a general methodology that we call spectral neural network (SNN) which enables to generate automatically knowing a few datapoints (eight at most), a sound and plausible yield surface for any variations of a given anisotropic material, e.g. batches of the same material or same type of material produced by a different supplier. It relies on the use of a reliable parametrization of a performant analytic orthotropic yield function for the generation of a large database of yield surface shapes and the singular value decomposition method to create a reduced basis. For a specific material, a surrogate model for the reduced basis coordinates is further constructed using few additional datapoints. The dense neural network is built such as to ensure that the invariance requirements dictated by the material symmetry as well as the convexity of the yield surface are automatically enforced. The capabilities of this new methodology are demonstrated for hexagonal closed packed materials titanium materials, which are known to be particularly challenging to model due to their anisotropy and tension-compression asymmetry. Furthermore, we show that the SNN methodology can be extended such as to include variations of multiple materials of vastly different plastic behavior and yield surface shapes. The in-depth analysis presented reveals the benefits and limits of the hybrid data-driven models for description of anisotropic plasticity.

在本文中,我们提出了一种通用的方法,我们称之为光谱神经网络(SNN),它能够自动生成知道几个数据点(最多八个),对于给定各向异性材料的任何变化,例如,由不同供应商生产的相同材料或相同类型的材料的批次,合理且合理的屈服面。它依赖于使用可靠的参数化高性能的解析正交各向异性屈服函数来生成屈服曲面形状的大型数据库,并使用奇异值分解方法来创建约简基。对于特定材料,使用少量附加数据点进一步构建简化基坐标的代理模型。建立了密集神经网络,以确保自动执行材料对称性和屈服面凹凸性所决定的不变性要求。这种新方法的能力在六边形封闭填充材料钛材料中得到了证明,由于其各向异性和拉伸压缩不对称性,这种材料的建模特别具有挑战性。此外,我们表明SNN方法可以扩展,例如包括多种具有不同塑性行为和屈服面形状的材料的变化。深入的分析揭示了混合数据驱动模型描述各向异性塑性的优点和局限性。


Mechanics of Materials

Modeling electromechanical behaviors of soft conductive composites embedded with liquid metal fibers

Quang-Kha Nguyen, Pu Zhang

doi:10.1016/j.mechmat.2024.104920

嵌入液态金属纤维的软导电复合材料机电行为建模

Soft conductive materials are key components of soft electronics, sensors, actuators, and wearable devices. The electrical conductivity matrix or tensor of soft conductive materials is usually deformation-dependent, but there is a lack of constitutive modeling work on it. To fill this knowledge gap, we consider a soft conductive composite embedded with liquid metal fibers as an example. The difference between the material conductivity and spatial conductivity is clarified briefly. In addition, we devise two constitutive models for the deformation-dependent conductivity tensors. These two models are equivalent but in different formats, one using stretch ratios and the other using invariants. Besides the conductivity models, a transversely isotropic hyperelastic model is also presented to model the mechanical behaviors. These analytical models are fitted and validated using data from multiphysics computational modeling on representative volume elements. Note that the proposed models can also be used for other soft conductive materials as well as thermal conductivity modeling.

软导电材料是软电子、传感器、执行器和可穿戴设备的关键部件。软导电材料的导电性矩阵或张量通常是与变形相关的,但缺乏对其进行本构建模的工作。为了填补这一知识空白,我们以嵌入液态金属纤维的软导电复合材料为例。简要阐明了材料电导率与空间电导率的区别。此外,我们设计了变形相关的导电性张量的两个本构模型。这两个模型是等价的,但格式不同,一个使用拉伸比,另一个使用不变量。除了电导率模型外,还提出了横向各向同性超弹性模型来模拟力学行为。这些分析模型是用代表性体元的多物理场计算建模数据拟合和验证的。请注意,所提出的模型也可用于其他软导电材料以及导热性建模。


Thin-Walled Structures

Parameter optimization of friction stir spot welded Al 6061 and CFRTP PA6 with surface treatment and interfacial adhesion

Yu Guo, Haibin Zhao, Caijiao Ai, Jingjing Zhao, Hao Su, Ji Chen, Guoqun Zhao

doi:10.1016/j.tws.2024.111585

Al 6061与CFRTP PA6搅拌摩擦点焊表面处理及界面附着力参数优化

The multiple material design of lightweight structural components of new energy vehicles imposes high demands on the joint of Al alloy and CFRTP composite. This study explored the fabrication of high joint strength between Al alloy 6061 and CFRTP PA6 composites through the laser ablation on Al alloy surface and friction stir spot welding (FSSW) process. By experimental optimization of the FSSW parameters, including rotational speed, displacement, and dwelling time, a remarkable tensile shear force of 10.282 kN was achieved under the rotational speed of 2000 rpm, displacement of 3 mm, and dwelling time of 10 s. The interfacial morphology of the Al alloy/CFRTP joint was characterized in detail. The microstructure analysis revealed a number of physical anchoring areas formed at the joint interface of laser-ablated Al alloy and CFRTP PA6. The PA6 resin of the CFRTP could be fully melted and effectively fill the grooves on the laser-ablated Al alloy surface due to the compression load and heat output at a high rotational speed and dwelling time.

新能源汽车轻量化结构件的多材料设计对铝合金与CFRTP复合材料的接合提出了很高的要求。本研究探讨了采用铝合金表面激光烧蚀和搅拌摩擦点焊(FSSW)工艺制备高强度铝合金6061与CFRTP PA6复合材料的结合。通过对FSSW的转速、位移和停留时间等参数进行实验优化,在转速为2000 rpm、位移为3 mm、停留时间为10 s的条件下,获得了10.282 kN的显著拉伸剪切力。对铝合金/CFRTP接头的界面形貌进行了详细的表征。显微组织分析表明,激光烧蚀铝合金与CFRTP PA6的接合界面处形成了大量的物理锚定区。CFRTP的PA6树脂在高转速和停留时间下的压缩载荷和热输出可以充分熔化并有效填充激光烧蚀铝合金表面的凹槽。


A series of auxetic metamaterials with negative thermal expansion based on L-shaped microstructures

Qiao Zhang, Yuxin Sun

doi:10.1016/j.tws.2024.111596

基于l型微结构的一系列负热膨胀的消热超材料

Mechanical metamaterials are facing various multi-functional requirements. In this study, a series of auxetic metamaterials with enhanced negative thermal expansion and improved stiffness are proposed. These metamaterials consist of four novel L-shaped microstructures connected in various clockwise or counterclockwise directions. Two length ratios and four angle parameters are utilized to define the geometry of these metamaterials. Both analytical analysis and validated numerical homogenization methods are employed to determine their effective thermoelastic properties, including effective Young's modulus, Poisson's ratio, and coefficient of thermal expansion. It is demonstrated that tailoring these microstructural geometries can modulate the effective thermoelastic properties of these metamaterials accordingly. By appropriately tailoring the geometric parameters, these metamaterials exhibit increased effective stiffness as well as more pronounced auxeticity and negative thermal expansion compared to traditional triangle and trapezoid microstructures. Notably, the in-plane effective anisotropic or isotropic Poisson's ratio and coefficient of thermal expansion can be adjustable over a broader range from negative to positive values. High stiffness, High strength, and near-zero thermal expansion can be achieved concurrently in these metamaterials, which is very conducive for structural designing in thermal environments. These metamaterials with a coupled design of stiffness, thermal expansion, and Poisson's ratio hold significant potential for advancing applications in satellite platforms, space structures, composite sandwiches, and precision equipment.

机械超材料正面临着各种各样的多功能需求。在本研究中,提出了一系列增强负热膨胀和提高刚度的增氧超材料。这些超材料由四个新颖的l形微结构组成,以不同的顺时针或逆时针方向连接。利用两个长度比和四个角度参数来定义这些超材料的几何形状。采用解析分析和经过验证的数值均匀化方法确定了其有效热弹性特性,包括有效杨氏模量、泊松比和热膨胀系数。结果表明,调整这些微观结构几何形状可以相应地调节这些超材料的有效热弹性性能。通过适当调整几何参数,与传统的三角形和梯形微结构相比,这些超材料表现出更高的有效刚度、更明显的塑性和负热膨胀。值得注意的是,平面内有效各向异性或各向同性泊松比和热膨胀系数可以在更宽的范围内从负值到正值进行调节。这些超材料可以同时实现高刚度、高强度和近零热膨胀,这对热环境下的结构设计非常有利。这些具有刚度、热膨胀和泊松比耦合设计的超材料在卫星平台、空间结构、复合夹层和精密设备中具有巨大的应用潜力。


Forced vibration response prediction of Miura-ori core sandwich panel with impact defects

Changyuan Ge, Caihua Zhou, Shijian Xiao, Mingfa Ren, Bo Wang

doi:10.1016/j.tws.2024.111597

含冲击缺陷的Miura-ori芯芯夹芯板的强迫振动响应预测

Miura-ori core sandwich panels have great application potential in aviation aircraft. Subject to the impact and vibration loads, the small impact defect will increase the dynamic stress, resulting in fatigue failure. Moreover, the Miura creases complicate the impact deformation, which is extremely time-consuming to analysis the dynamic stress only through simulation. Therefore, a rapid dynamic stress prediction method for Miura-ori core sandwich panels is first proposed based on the predicted impact deformation by arbitrary defects in this paper. The dynamic stress of sandwich panels could be directly calculated with few numerical results by establishing the relationship with impact deformation in advance. The vibration mechanism of sandwich panels with defects is revealed. Although the deformation area is below 32.1% of Miura cell projection area, the dynamic stress will increase by 1.984-2.635 times with different defects. The impact deformation is predicted by the geometric relationship of Miura creases and material properties, and the prediction errors of hemispherical and drilling defects with arbitrary defect positions are below 12.5% and 10.6%, respectively. Taking two types of defects (hemispherical and drilling defects), different defect depths and positions into consideration, the prediction errors of maximum dynamic stress are from -7.9% to 16.8% compared to simulation.

三浦ori芯芯夹芯板在航空飞机上具有很大的应用潜力。在冲击和振动载荷作用下,微小的冲击缺陷会使动应力增大,导致疲劳失效。此外,Miura折痕使冲击变形复杂化,仅通过仿真分析动应力非常耗时。因此,本文首次提出了一种基于任意缺陷冲击变形预测的Miura-ori芯芯夹层板动态应力快速预测方法。通过预先建立夹层板的动应力与冲击变形的关系,可以直接计算夹层板的动应力,而计算结果很少。揭示了含缺陷夹层板的振动机理。虽然变形面积小于Miura胞体投影面积的32.1%,但不同缺陷的动应力会增加1.984-2.635倍。利用Miura折痕与材料性能的几何关系预测冲击变形,对于任意缺陷位置的半球形缺陷和钻孔缺陷,预测误差分别在12.5%和10.6%以下。考虑两种缺陷类型(半球形缺陷和钻孔缺陷)、不同缺陷深度和位置,最大动应力预测误差为-7.9% ~ 16.8%。



来源:复合材料力学仿真Composites FEM
ACTMechanicalFluxMAGNETDeform振动疲劳复合材料非线性通用航空汽车电子新能源参数优化理论材料曲面
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首次发布时间:2024-11-05
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【新文速递】2023年12月30日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 2 篇,Journal of the Mechanics and Physics of Solids 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇International Journal of Solids and StructuresPhase-field modeling of anisotropic crack propagation based on higher-order nonlocal operator theoryNhon Nguyen-Thanh, Timon Rabczukdoi:10.1016/j.ijsolstr.2023.112632基于高阶非局部算子理论的各向异性裂纹扩展相场建模This paper presents a novel higher-order nonlocal operator theory for the phase-field modeling of brittle fracture in anisotropic materials. Incorporating higher order nonlocal operators can enhance the accuracy of the phase-field model by effectively capturing long-range interactions that hold significance in numerous materials. The reproducing kernel particle method is employed to derive a nonlocal differential operator to enhance computational stability and accuracy. Moreover, the proposed method eliminates the need for direct computation of derivatives of the modified kernel function, which avoids the calculation of moment matrix derivatives and improves computational efficiency. The phase-field modeling of polycrystalline materials, considering the anisotropic fracture resistance of each grain, is implemented using this numerical framework. The present method is able to capture different scenarios intergranular and transgranular crack propagation patterns in polycrystalline materials. The proposed method involves a detailed representation of the complex process of crack initiation and propagation in 2D and 3D models of polycrystalline materials.提出了一种新的高阶非局部算子理论,用于各向异性材料脆性断裂相场建模。结合高阶非局部算符可以通过有效地捕获在许多材料中具有重要意义的远程相互作用来提高相场模型的准确性。采用再现核粒子法推导非局部微分算子,提高了计算的稳定性和精度。此外,该方法不需要直接计算修正核函数的导数,避免了矩矩阵导数的计算,提高了计算效率。采用该数值框架对多晶材料进行了相场建模,考虑了各晶粒的抗断裂性能各向异性。该方法能够捕获多晶材料中不同情况下的晶间和穿晶裂纹扩展模式。该方法在二维和三维多晶材料模型中详细描述了裂纹萌生和扩展的复杂过程。Fracture resistance enhanced by both nonlocal interaction and damping of locally resonant structureXuan Zhang, Yi-Ze Wangdoi:10.1016/j.ijsolstr.2023.112635非局部相互作用和局部共振结构的阻尼增强了抗断裂能力In this study, the arrest behavior of locally resonant structure with nonlocal interaction and damping are analyzed. Based on the Wiener-Hopf method, the energy release ratio G0/G which denotes the arrest property is derived. The effects of nonlocal interaction and damping parameters on the oscillation and stability regions during the crack growth are discussed. The arrest characteristics of three locally resonant structures are compared. In order to support the theoretical calculation, both the finite element simulation and fracture experiment are performed. Results show that the locally resonant structure with nonlocal interaction and damping has smaller energy release ratio G0/G. It indicates that the coupling of both nonlocal interaction and damping can significantly enhance the propagation resistance of crack propagation.本研究分析了具有非局部相互作用和阻尼的局部谐振结构的阻滞行为。基于 Wiener-Hopf 方法,推导出了表示停滞特性的能量释放比 G0/G。讨论了非局部相互作用和阻尼参数对裂纹生长过程中振荡区和稳定区的影响。比较了三种局部共振结构的抑制特性。为了支持理论计算,进行了有限元模拟和断裂实验。结果表明,具有非局部相互作用和阻尼的局部共振结构的能量释放比 G0/G 较小。这表明,非局部相互作用和阻尼的耦合可以显著增强裂纹的抗扩展能力。Journal of the Mechanics and Physics of SolidsRate Induced Thermomechanical Interactions in NiTi Tensile Tests on StripsSolon Tsimpoukis, Stelios Kyriakidesdoi:10.1016/j.jmps.2023.105530带材镍钛拉伸试验中速率诱导的热-机械相互作用The paper uses tensile experiments on NiTi strips at different displacement rates to establish and simulate the thermomechanical interactions caused by the latent heat of the reversible transformation between the austenitic and martensitic phases. The evolution of deformation in the specimen is synchronously monitored with digital image correlation, and the temperature field through infrared imaging, essential for structural modelling. Transformation leads to localized deformation that propagates through the specimen, while the latent heat released/absorbed at the propagating fronts locally heats/cools the specimen. The sensitivity of the transformation stress to temperature results in a complex interaction between the heat transfer conditions and the nucleation and evolution of transformation in the specimen. At low rates of loading, the alternate phase propagates nearly isothermally with a small number of fronts producing relatively flat stress plateaus. Higher rates lead to significant heating/cooling that results in progressive nucleation of multiple fronts and apparent "hardening" responses. The experiments are simulated in a three-dimensional static displacement transient temperature finite element analysis, using a new fully coupled thermomechanical constitutive model. Transformation strain and entropy are its internal variables whose evolution is governed by the motion in the stress-temperature space of a single transformation surface governing both transformations. The prevailing localization is captured by the introduction of softening over the unstable branches of the recorded isothermal material response. The results demonstrate how the important role of the thermal interaction between the specimen and the environment can be addressed. This, together with appropriate calibration of the constitutive and structural model, enable the analysis to reproduce the effect of rate on the recorded response, the evolution of localization patterns, and the associated thermal fields. The results can guide the development of constitutive and structural models of phase transforming materials with strong thermomechanical interactions.本文采用不同位移速率下NiTi带材的拉伸实验,建立并模拟了奥氏体与马氏体可逆相变潜热引起的热力相互作用。通过数字图像相关同步监测试样的变形演变,并通过红外成像同步监测温度场,这对结构建模至关重要。相变导致局部变形在试样中传播,而在传播前沿释放/吸收的潜热局部加热/冷却试样。相变应力对温度的敏感性导致传热条件与试样的形核和相变演化之间存在复杂的相互作用。在低加载速率下,交替相几乎等温传播,少数锋面产生相对平坦的应力高原。较高的速率导致显著的加热/冷却,导致多个锋面逐渐成核和明显的“硬化”反应。采用一种新的全耦合热-力本构模型,对实验进行了三维静位移瞬态温度有限元模拟。相变应变和熵是其内部变量,其演化由控制两种相变的单一相变表面在应力-温度空间中的运动决定。通过在记录的等温材料响应的不稳定分支上引入软化,捕获了普遍的局部化。结果表明,如何在试样和环境之间的热相互作用的重要作用可以解决。这与本构和结构模型的适当校准一起,使分析能够重现速率对记录响应的影响,定位模式的演变以及相关的热场。研究结果对具有强热力相互作用的相变材料的本构模型和结构模型的建立具有指导意义。International Journal of PlasticityRevealing the effects of martensitic transformation and dislocation slip in austenite on the micromechanical behaviors of a 9Ni steel using crystal plasticity finite element methodW.X. Zhang, Y.B. Cong, J. Wang, C. Li, J. Wan, Y.Z. Chendoi:10.1016/j.ijplas.2023.103869 利用晶体塑性有限元法揭示了马氏体相变和奥氏体 位错滑移对9Ni钢微观力学行为的影响Austenite is an extremely important phase that significantly influence the mechanical properties of (austenite + martensite) duplex steels. Two different deformation mechanisms, i.e., dislocation slip and martensitic transformation, can be activated in the austenite upon plastic deformation. However, these two deformation mechanisms make different contributions to the work hardening and flow stress of the austenite which are hardly separated by experimental methods, making it difficult to clarify the effect of austenite on the micromechanical behavior of (austenite + martensite) duplex steels. In this work, the influence of martensitic transformation and dislocation slip in austenite on the micromechanical behaviors is investigated in a model 9Ni steel consisting of austenite and tempered martensite (TM) using the crystal plasticity finite element method (CPFEM). The austenite and fresh martensite (FM) formed within the austenite grain upon deformation process are regarded as a whole named as FM/A island in the CPFEM. To accurately model the rate of martensitic transformation, the martensitic transformation kinetics law used in the CPFEM is developed by relating the number of possible nucleation sites for fresh martensite to the mechanical driving force originating from the resolved shear stress on each transformation system. The material parameters for the TM were determined by micropillar compression tests. Besides, the method for separating and determining the material parameters accounting for dislocation slip in austenite and martensitic transformation by a combination of neutron diffraction and measurements of stress-strain curves and austenite volume fractions is developed and exemplified. The CPFEM simulation results show that the local concentration of equivalent plastic strain and stress triaxiality in the FM/A island can be enhanced by the dislocation slip in austenite but suppressed by the martensitic transformation. In addition, the martensitic transformation has a remarkable effect on strengthening the local concentration of maximum principal stress in the FM/A island.奥氏体是影响(奥氏体 + 马氏体)双相钢力学性能的重要相。塑性变形时,奥氏体可激活两种不同的变形机制,即位错滑移和马氏体相变。然而,这两种变形机制对奥氏体的加工硬化和流动应力的贡献各不相同,且难以通过实验方法加以区分,因此很难阐明奥氏体对(奥氏体 + 马氏体)双相钢微观力学行为的影响。本文采用晶体塑性有限元法(CPFEM)研究了奥氏体和回火马氏体(TM)组成的9Ni钢中马氏体相变和位错滑移对微观力学行为的影响。在CPFEM中,将形变过程中在奥氏体晶粒内形成的奥氏体和新马氏体(FM)视为一个整体,称为FM/ a岛。为了准确地模拟马氏体转变的速率,CPFEM中使用的马氏体转变动力学定律是通过将新马氏体可能成核的位置的数量与每个转变系统上由分解的剪切应力产生的机械驱动力相关联而建立的。通过微柱压缩试验确定了TM的材料参数。此外,还提出了利用中子衍射、应力-应变曲线和奥氏体体积分数测量相结合的方法来分离和确定奥氏体和马氏体相变中位错滑移的材料参数。CPFEM模拟结果表明,奥氏体 位错滑移增强了FM/A岛的局部等效塑性应变集中和应力三轴性,但马氏体相变抑制了等效塑性应变的集中。此外,马氏体相变对强化FM/ a岛局部最大主应力集中有显著作用。Thin-Walled StructuresExperimental and numerical study on the lightweight design of load-bearing energy absorption structure for subway trainJialin Li, Guangjun Gao, Yao Yu, Tianyu Zhuo, Jian Lidoi:10.1016/j.tws.2023.111542地铁列车承载吸能结构轻量化设计的试验与数值研究The load-bearing underframe is widely utilized on the crashworthiness design of subway trains. However, studies on load-bearing underframes mainly focused on conceptual design and structural optimization, and didn't consider the combination of bearing loads during the normal operation and absorbing impact kinetic energy under collisions. In addition, the traditional load-bearing underframe for subway trains is mainly made of stainless steel, which has a relatively large weight and cannot meet the requirement of lightweight design. To address these limitations, this paper presents a novel lightweight aluminum alloy load-bearing underframe with the alternative thin-walled energy absorption component, which can both satisfy the function of bearing loads and energy absorption. Firstly, the impact tests and numerical simulations are conducted to compare the crashworthiness of the energy absorption component, i.e., the thin-walled square tube made of S304 (abbreviated as S3N4) and aluminum alloy 5083P-O (abbreviated as A3N4). The result shows that S3N4 has higher energy absorption and mean crushing force, and A3N4 is 56.94 % lower than S3N4 in initial peak crushing force and 53.79 % higher in special energy absorption. Then, the aluminum alloy thin-walled tube is adopted on the novel load-bearing underframe and the parameter study on the wall thickness and number of diaphragms for the energy absorption component is conducted. The result reveals that the 5083P-O thin-walled tube with 5 mm wall thickness and 4 diaphragms can provide the stable and ordered deformation mode and high energy absorption. Finally, a real vehicle impact test is conducted to verify the crashworthiness of the optimized load-bearing underframe, which shows that the deformation modes and mechanical responses are consistent with the numerical simulation. The proposed aluminum alloy load-bearing underframe energy absorption structure can be adopted on subway trains.在地铁列车的耐撞性设计中,承重型车架得到了广泛的应用。然而,对承重型车架的研究主要集中在概念设计和结构优化上,没有考虑车架正常运行时承受载荷与碰撞时吸收冲击动能的结合。此外,传统的地铁列车承重底架以不锈钢为主,自重较大,不能满足轻量化设计的要求。针对这些局限性,本文提出了一种新型的轻质铝合金承载底架,并采用替代薄壁吸能组件,既能满足承载载荷又能满足吸能功能。首先,对S304薄壁方管(简称S3N4)和5083P-O铝合金(简称A3N4)两种吸能构件的耐撞性进行了冲击试验和数值模拟比较。结果表明,S3N4具有更高的能量吸收和平均破碎力,A3N4初始峰值破碎力比S3N4低56.94%,特殊能量吸收比S3N4高53.79%。然后,在新型承力底架上采用铝合金薄壁管,对吸能构件的壁厚和隔板数进行了参数研究。结果表明:5083P-O薄壁管的壁厚为5mm,隔板为4个,可以提供稳定有序的变形模式和较高的能量吸收。最后,进行了实车碰撞试验,验证了优化后的承载底架的耐撞性,结果表明,其变形模式和力学响应与数值模拟结果一致。本文提出的铝合金承力底架吸能结构可用于地铁列车。An all-composite sandwich structure with PMI foam-filled for adjustable vibration suppression and improved mechanical propertiesJiaming Sun, Leilei Yan, Keyu Zhu, Pengfei Jiang, Yanlong Xu, Xitao Zhengdoi:10.1016/j.tws.2023.111544采用PMI泡沫填充的全复合夹层结构,可调抑制振动,提高力学性能A novel all-composite double-layer sandwich structure with tubular cores (DSST) is designed and fabricated to achieve the both of vibration suppression and enhancement of mechanical properties. The suppression effect of the proposed sandwich structure on the structural vibration is verified numerically and experimentally, and the mechanism of bandgap generation as well the structural wave propagation modes are revealed and analyzed. The anisotropy of the carbon fiber reinforced polymer (CFRP) is utilized to enables the intermediate resonant layer to exist a wide frequency adjustment range of vibration suppression without altering its geometrical parameters. Then, the improvement of structural vibration characteristics (i.e., natural frequencies and mode shapes) by filling the polymethacrylimide (PMI) foam in the DSST is discussed. And PMI foam-filling also leads to improved mechanical properties, out-of-plane compression tests are conducted to reveal the mechanism of mechanical enhancement, and it is found that the interaction effect of the foam filled in DSST in the axial direction enhances the compressive strength and the specific energy absorption (SEA) compared to the one without foam by 35.7% and 26.2%, respectively. In addition, the core configuration and the composite material preparation enable the proposed structure to outperform competing ones in terms of load-bearing capacity and bandgap characteristics.设计并制造了一种新型的双层管状芯夹芯全复合材料结构(DSST),以达到抑制振动和提高力学性能的目的。通过数值和实验验证了夹层结构对结构振动的抑制作用,揭示和分析了带隙产生的机理以及结构波的传播模式。利用碳纤维增强聚合物(CFRP)的各向异性,使中间谐振层在不改变其几何参数的情况下存在较宽的频率调节范围来抑制振动。然后讨论了在DSST中填充聚甲基丙烯酰亚胺(PMI)泡沫对结构振动特性(即固有频率和振型)的改善。PMI泡沫填充也能改善材料的力学性能,通过面外压缩试验揭示了力学增强的机理,结果发现,在轴向填充泡沫后,材料的抗压强度和比能吸收(SEA)比未填充泡沫时分别提高了35.7%和26.2%。此外,核心配置和复合材料制备使所提出的结构在承载能力和带隙特性方面优于竞争结构。来源:复合材料力学仿真Composites FEM

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