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【新文速递】2024年9月6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 2 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇

International Journal of Solids and Structures

A “poor-man’s” deformation plasticity based approach to topology optimization of elastoplastic structures

Kai Li, Mathias Wallin, Matti Ristinmaa, Gengdong Cheng

doi:10.1016/j.ijsolstr.2024.113056

基于“穷人”变形塑性的弹塑性结构拓扑优化方法

This paper presents a topology optimization framework utilizing a deformation plasticity model to approximate the isotropic hardening von-Mises incremental elastoplasticity model under monotone proportional loading. One advantage of the model is that it is based on a yield surface allowing for precise matching to uniaxial elastoplastic isotropic hardening response. The deformation plasticity model and the incremental plasticity model coincides for proportional loading and since the deformation plasticity model is path-independent, the computational cost and implementation complexity reduce significantly compared to the conventional incremental elastoplasticity. To investigate the deformation plasticity model combined with topology optimization, we compare three common elastoplastic optimization objectives: stiffness, strain energy and plastic work. The possibility to limit the peak local plastic work while maximizing the strain energy is also investigated. The consistent analytical sensitivity analysis which only requires the terminal state is derived using adjoint method. Numerical examples demonstrate that the proportionality assumption is reasonable and the deformation plasticity model combined with topology optimization is a competitive alternative to cumbersome incremental elastoplasticity.

本文提出了一种利用变形塑性模型近似单调比例加载下各向同性硬化von-Mises增量弹塑性模型的拓扑优化框架。该模型的一个优点是,它是基于屈服面,允许精确匹配的单轴弹塑性各向同性硬化响应。在比例加载条件下,变形塑性模型与增量塑性模型吻合,且由于变形塑性模型与路径无关,与传统增量弹塑性模型相比,计算成本和实现复杂度显著降低。为了研究与拓扑优化相结合的变形塑性模型,我们比较了三种常用的弹塑性优化目标:刚度、应变能和塑性功。在最大限度地提高应变能的同时限制局部塑性功峰值的可能性也进行了研究。利用伴随法导出了只要求终端态的一致性分析灵敏度分析。数值算例表明,比例假设是合理的,结合拓扑优化的变形塑性模型是替代繁琐的增量弹塑性的有力选择。


Mechanics of Materials

Physically recurrent neural network for rate and path-dependent heterogeneous materials in a finite strain framework

M.A. Maia, I.B.C.M. Rocha, D. Kovačević, F.P. van der Meer

doi:10.1016/j.mechmat.2024.105145

在有限应变框架下速率和路径相关非均质材料的物理递归神经网络

In this work, a hybrid physics-based data-driven surrogate model for the microscale analysis of heterogeneous material is investigated. The proposed model benefits from the physics-based knowledge contained in the constitutive models used in the full-order micromodel by embedding the material models in a neural network. Following previous developments, this paper extends the applicability of the physically recurrent neural network (PRNN) by introducing an architecture suitable for rate-dependent materials in a finite strain framework. In this model, the homogenized deformation gradient of the micromodel is encoded into a set of deformation gradients serving as input to the embedded constitutive models. These constitutive models compute stresses, which are combined in a decoder to predict the homogenized stress, such that the internal variables of the history-dependent constitutive models naturally provide physics-based memory for the network. To demonstrate the capabilities of the surrogate model, we consider a unidirectional composite micromodel with transversely isotropic elastic fibers and elasto-viscoplastic matrix material. The extrapolation properties of the surrogate model trained to replace such micromodel are tested on loading scenarios unseen during training, ranging from different strain-rates to cyclic loading and relaxation. Speed-ups of three orders of magnitude with respect to the runtime of the original micromodel are obtained.

在这项工作中,研究了一种基于混合物理的数据驱动代理模型,用于非均质材料的微尺度分析。该模型通过将材料模型嵌入到神经网络中,利用全阶微模型中本构模型中包含的物理知识。根据先前的发展,本文通过在有限应变框架中引入适用于速率相关材料的架构,扩展了物理递归神经网络(PRNN)的适用性。该模型将微模型的均匀化变形梯度编码为一组变形梯度,作为嵌入本构模型的输入。这些本构模型计算应力,这些应力组合在一个解码器中以预测均匀的应力,这样,依赖于历史的本构模型的内部变量自然地为网络提供基于物理的记忆。为了证明替代模型的能力,我们考虑了一个具有横向各向同性弹性纤维和弹粘塑性基体材料的单向复合微模型。在训练期间未见的加载场景下,从不同的应变率到循环加载和松弛,测试了替代微模型的替代模型的外推特性。相对于原始微模型的运行时间,获得了三个数量级的加速。


Effect of porous microstructure and fiber arrangement of thermal protection composites on effective thermal conductivity

Fan Yang, Weihua Xie, Songhe Meng

doi:10.1016/j.mechmat.2024.105147

热防护复合材料的孔隙结构和纤维排列对有效导热系数的影响

The inclusions in a high-temperature resistant matrix can significantly influence the radiative heat transfer of composite materials at elevated temperatures; therefore, the microstructure design of composites for thermal protection during atmospheric re-entry require a more accurate prediction of thermal insulation performance. In this paper, the Rosseland approximation was used to investigate the radiative heat transfer within thermal protection materials, e.g., porous carbon-based material and ultra-high-temperature ceramics (e.g., ZrB2-SiC), and the discrete dipole scattering method was used to evaluate the extinction efficiency across the inclusions with different types of microstructures. The effect of inclusion parameters, such as inclusion size, shape coefficient, volume fraction, orientation, and size distribution, on the radiative and effective thermal conductivity (ETC) at various temperatures was analyzed in detail. Test results obtained from the existing literature were used to validate the ETC of porous ceramics predicted by the proposed model. The results indicated that the microstructures in thermal protection materials play a fundamental role in improving the heat-shielding properties. The present study deepens the understanding of the relationship between microstructures and thermal radiation properties and provides theoretical design guidelines for thermal protection materials with improved thermal insulation properties.

耐高温基体中的夹杂物对复合材料在高温下的辐射传热有显著影响;因此,用于大气再入热防护的复合材料微结构设计需要对其隔热性能进行更精确的预测。本文采用Rosseland近似研究了多孔碳基材料和超高温陶瓷(如ZrB2-SiC)等热防护材料内部的辐射传热,并采用离散偶极子散射方法评估了不同类型显微结构夹杂间的消光效率。详细分析了包裹体尺寸、形状系数、体积分数、取向、尺寸分布等参数对不同温度下的辐射导热系数和有效导热系数的影响。利用现有文献的测试结果验证了所提出模型预测的多孔陶瓷的ETC。结果表明,热防护材料的显微组织对热防护性能的提高起着至关重要的作用。本研究加深了对微结构与热辐射性能关系的认识,为提高隔热性能的热防护材料的设计提供了理论指导。


International Journal of Plasticity

Influence of textural variability on plastic response of porous crystal embedded in polycrystalline aggregate: A crystal plasticity study

Sagar Chandra, Suranjit Kumar, Mahendra K. Samal, Vivek M. Chavan

doi:10.1016/j.ijplas.2024.104117

多晶骨料中嵌入多孔晶体的织构变化对塑性响应的影响:晶体塑性研究

Damage evolution in polycrystalline aggregates is complicated by the intricate interplay of crystallographic orientation of the porous grain and the surrounding anisotropic matrix. Therefore, formulation of design rules and damage models for polycrystalline materials proves daunting due to relative lack of thorough understanding of the underlying heterogeneity at the mesoscale. This work explores the orientation dependent void growth in a porous crystal embedded in an anisotropic polycrystalline matrix with different initial textures. Polycrystalline face-centered cubic based aggregate is simulated within the framework of crystal plasticity finite element method. Porosity is first modeled in the form of a single pre-existing spherical void in the central grain of the randomly oriented polycrystal. One-hundred crystallographic orientations of the central grain in three-dimensional Euler space are analyzed to reveal the orientation dependent trends of the porous grain. To account for textural variability, the analysis is repeated for polycrystals exhibiting preferred textures like Cube, Brass, Copper and Goss. In this manner, interesting orientation dependent trends in basic tenets of void growth like yield strength, coalescence strain and porosity evolution are unraveled across various polycrystalline textures. To account for spatial heterogeneity as well, porosity in the central grain is then re-distributed and the aforementioned analysis is repeated for all the crystallographic orientations of the central grain embedded in polycrystals with different textures. Owing to the large amount of data thus generated, statistical analysis is invoked to identify stimulating trends and key statistical variables governing the strength and toughness. Consequently, a statistical void growth model is also presented by assessing the CP simulation results and identifying suitable distribution function governing the growth of voids in polycrystals. The modeling framework is expected to inform porous plasticity models aimed at capturing damage evolution in porous grains embedded in polycrystalline materials exhibiting topological and crystallographic anisotropy.

多孔颗粒的晶体取向与周围各向异性基体的相互作用使多晶团聚体的损伤演化变得复杂。因此,由于相对缺乏对中尺度潜在非均质性的透彻理解,多晶材料的设计规则和损伤模型的制定是艰巨的。本研究探索了嵌入在具有不同初始结构的各向异性多晶基质中的多孔晶体中与取向相关的空洞生长。采用晶体塑性有限元法对多晶面心立方基骨料进行了数值模拟。孔隙度首先以随机取向多晶的中心颗粒中单个预先存在的球形空隙的形式建模。对中心晶粒在三维欧拉空间的100个晶体取向进行了分析,揭示了多孔晶粒的取向依赖趋势。为了解释纹理的可变性,对具有立方体、黄铜、铜和高斯等优选纹理的多晶重复分析。通过这种方式,在不同的多晶结构中揭示了屈服强度、聚结应变和孔隙度演化等空洞生长基本原理中有趣的取向依赖趋势。为了考虑空间异质性,中心晶粒的孔隙度被重新分配,并对嵌入在不同纹理的多晶体中的中心晶粒的所有晶体取向重复上述分析。由于产生了大量的数据,因此需要进行统计分析,以确定刺 激的趋势和控制强度和韧性的关键统计变量。在此基础上,通过对CP模拟结果的评估,确定了控制多晶中孔洞生长的合适分布函数,提出了孔洞生长的统计模型。该模型框架有望为多孔塑性模型提供信息,这些模型旨在捕捉嵌入在具有拓扑和晶体各向异性的多晶材料中的多孔颗粒的损伤演变。


Thin-Walled Structures

Free vibration analysis of a functionally graded porous triangular plate with arbitrary shape and elastic boundary conditions using an isogeometric approach

Milad Izadi, Maryam Abedi, Paolo S. Valvo

doi:10.1016/j.tws.2024.112422

用等几何方法分析任意形状和弹性边界条件下功能梯度多孔三角形板的自由振动

This paper presents a comprehensive analysis of the free vibrations of functionally graded porous (FGP) triangular plates with arbitrary shapes and elastic boundary conditions using Isogeometric Analysis (IGA). We express the triangular shapes by using non-uniform rational B-splines (NURBS). The impact of porosity, geometry, and boundary conditions on the natural frequencies is investigated, with a focus on three key factors: porosity coefficient, geometric shape, and type of boundary conditions. Results show that increasing porosity generally leads to an increase in natural frequencies for thin plates, while thicker plates exhibit the opposite trend. The effect of geometric shape, characterized by different angles, is investigated and reveals distinct trends in natural frequencies. The study also investigates both classical and elastic boundary conditions, illustrating the impact of arbitrary boundary conditions on the natural frequency response. Validation against previous references and finite element methods establishes the accuracy of the presented results. The paper concludes with an extension of the analysis to various scenarios, offering valuable insights into the intricate interplay of porosity, geometry, and boundary conditions on the vibrational behavior of FGP triangular plates.

本文采用等几何分析方法对具有任意形状和弹性边界条件的功能梯度多孔(FGP)三角形板的自由振动进行了综合分析。用非均匀有理b样条(NURBS)表示三角形。研究了孔隙度、几何形状和边界条件对固有频率的影响,重点研究了孔隙度系数、几何形状和边界条件类型这三个关键因素。结果表明,孔隙率的增加通常会导致薄板固有频率的增加,而厚板则相反。研究了不同角度的几何形状的影响,揭示了固有频率的不同趋势。该研究还研究了经典边界条件和弹性边界条件,说明了任意边界条件对固有频率响应的影响。通过对先前文献和有限元方法的验证,确定了所提出结果的准确性。本文最后将分析扩展到各种情况,为FGP三角形板的振动行为的孔隙率,几何形状和边界条件的复杂相互作用提供了有价值的见解。


On energy absorption capability and controllable failure modes of CFRP circular tube using numerical simulation

Hongyuan Yang, Yiru Ren

doi:10.1016/j.tws.2024.112423

基于数值模拟的CFRP圆管能量吸收能力及可控失效模式研究

Enhancing the energy absorption (EA) capacity of carbon fiber reinforced plastic (CFRP) structures by inducing controlled failure modes is significant for lightweight design in aerospace. In the present work, four triggers including inward horizontal trigger, inward tilted trigger, outward horizontal trigger and outward tilted trigger are proposed to induce specific failure modes of CFRP circular tubes under axial loading. Under the framework of maximum stress and traction-separation damage criterion, the numerical model that can accurately predict load response and fracture behavior is established. The results showed that circular tubes with horizontal triggers have higher energy absorption (0.98%–15.62%). The circular tubes with tilted triggers were able to achieve higher crushing load efficiency (12.16%–22.97%). The damage state of the material becomes controllable and mainly manifests as tensile and compressive damage in the axial fiber direction. To clarify the strengthening mechanism, the influence of typical structural parameters of the trigger on the crashworthiness is investigated. It is found that increasing the groove width can effectively reduce the peak load. Finally, the controlled failure principle of CFRP tubes is analyzed and revealed. The results confirm the effectiveness of the trigger mechanism.

通过诱导可控失效模式来提高碳纤维增强塑料(CFRP)结构的吸能能力,对航空航天轻量化设计具有重要意义。本文提出了向内水平触发、向内倾斜触发、向外水平触发和向外倾斜触发四种触发机制来诱导CFRP圆管在轴向载荷作用下的特定破坏模式。在最大应力和牵引分离损伤准则框架下,建立了能够准确预测载荷响应和断裂行为的数值模型。结果表明,带水平触发装置的圆管吸能较高(0.98% ~ 15.62%)。带倾斜触发器的圆管具有较高的破碎负荷效率(12.16% ~ 22.97%)。材料的损伤状态变得可控,主要表现为纤维轴向的拉伸和压缩损伤。为阐明其强化机理,研究了触发器典型结构参数对其耐撞性的影响。研究发现,增大槽宽可以有效降低峰值荷载。最后,分析并揭示了CFRP管的可控失效原理。结果证实了该触发机构的有效性。




来源:复合材料力学仿真Composites FEM
ACTDeform振动断裂复合材料拓扑优化航空航天ADSUGUM理论化机材料控制
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首次发布时间:2024-11-21
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【新文速递】2024年9月9日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 4 篇International Journal of Solids and StructuresElastic wave propagation in cubic non-centrosymmetric and chiral architectured materials: Insights from strain gradient elasticityG. Rosi, N. Auffray, C. Combescuredoi:10.1016/j.ijsolstr.2024.113059弹性波在立方非中心对称和手性结构材料中的传播:来自应变梯度弹性的见解In this paper, we investigate wave propagation in cubic periodic architectured materials. We analyse three different types of unit cells, with distinct symmetries (centrosymmetric, non-centrosymmetric chiral and non-centrosymmetric achiral) with the aim of investigating the consequences of such symmetries on the elastodynamic behaviour of the architectured material. To this end, numerical simulations are performed on unit cells representative of the three types, to extract phase velocities and polarisations of waves along different directions. It is shown that some unconventional couplings between the different eigensolutions give rise to circular or elliptically polarised waves, associated with dispersive effects (acoustical activity). Subsequently, a theoretical analysis using a generalised equivalent continuum model (strain gradient elasticity) is performed to analyse these results and unveil the links between the symmetries of the architecture and the macroscopic elastodynamic behaviour. Indeed, it is shown that strain gradient elasticity is able to discriminate between the three symmetry classes, that are seen as equivalent by a classic continuum theory.本文研究了波在三次周期结构材料中的传播。我们分析了三种不同类型的单体细胞,具有不同的对称性(中心对称、非中心对称手性和非中心对称非手性),目的是研究这种对称性对结构材料弹性动力学行为的影响。为此,在具有代表性的三种类型的单元胞上进行了数值模拟,以提取波沿不同方向的相速度和极化。结果表明,不同特征解之间的一些非常规耦合会产生与色散效应(声学活动)相关的圆形或椭圆形极化波。随后,使用广义等效连续体模型(应变梯度弹性)进行理论分析,以分析这些结果,并揭示结构对称性与宏观弹性动力学行为之间的联系。事实上,它表明应变梯度弹性能够区分三种对称类,这被看作是等效的经典连续统理论。Journal of the Mechanics and Physics of SolidsSelf-consistent solution of the Frank-Bilby equation for interfaces containing disconnectionsDavid B. Gordon, Ryan B. Sillsdoi:10.1016/j.jmps.2024.105845含断路界面的Frank-Bilby方程的自洽解The quantized Frank-Bilby equation can be used to identify interfacial line defect array configurations which relax the misorientation and/or misfit of a coherent crystalline interface. These line defect arrays may be comprised of dislocations and/or disconnections, which are interfacial steps with dislocation character. When an interface contains disconnections, solution of the quantized Frank-Bilby equation is complicated by the fact that the habit plane orientation is not known in advance because it depends on the unknown spacing of the disconnection array. We present a root-finding-based method for addressing this issue, enabling a self-consistent solution for arbitrary defect content. Our method has been implemented in an open-source code which enumerates all possible solutions given a list of candidate line defects. Two cases are presented employing the code: a misoriented FCC twin boundary and an FCC/BCC phase boundary with the Nishiyama-Wasserman orientation relationship. Both cases exhibit more than 10,000 solutions to the Frank-Bilby equation, with several hundred solutions categorized as “low energy” and thus plausible configurations for the actual interface. The resulting set of solutions can be utilized to predict and understand the properties of a given interface.量子化的Frank-Bilby方程可以用来识别界面线缺陷阵列构型,从而缓解相干晶体界面的取向错误和/或失配。这些线缺陷阵列可以由位错和/或断开组成,这是具有位错特征的界面步骤。当界面包含断线时,由于习惯面方向取决于断线阵列的未知间距,因此无法预先知道习惯面方向,这使得量子化Frank-Bilby方程的求解变得复杂。我们提出了一种基于根查找的方法来处理这个问题,为任意缺陷内容提供自一致的解决方案。我们的方法已经在一个开放源代码中实现,该代码列举了给定候选行缺陷列表的所有可能的解决方案。给出了两种应用该代码的情况:错误取向的FCC双边界和具有Nishiyama-Wasserman取向关系的FCC/BCC相边界。这两种情况都展示了Frank-Bilby方程的10,000多个解,其中数百个解被归类为“低能量”,因此对于实际界面的合理配置。结果的解决方案集可以用来预测和理解给定接口的属性。International Journal of PlasticityA generalised framework for modelling anisotropic creep-ageing deformation and strength evolution of 2xxx aluminium alloysXi Wang, Zhusheng Shi, Jianguo Lindoi:10.1016/j.ijplas.2024.1041142xxx铝合金各向异性蠕变时效变形和强度演化的一般框架The 2xxx aluminium alloys are extensively applied in the aerospace industry due to their lightweight and balanced performance characteristics. However, a comprehensive method for modelling both the anisotropic creep deformation and strengthening behaviour in creep age forming (CAF) for 2xxx aluminium alloys remains lacking. This paper presents a generalised framework for establishing constitutive models capable of describing the anisotropic creep deformation coupled with the microstructure and material strength evolutions during creep-ageing of both the original and the pre-deformed 2xxx series Al alloys. This framework extends the rolling direction-based material model to anisotropic scenarios at varying angles between the loading and rolling directions, by employing the non-uniform rational B-splines (NURBS). The details about the anisotropic model calibration and numerical simulation implementation are demonstrated. The feasibility of this method was verified by its application to various 2xxx series aluminium alloys with or without pre-deformation, through constitutive modelling and numerical simulation, with satisfactory agreements between prediction and experimental data. For the first time, the proposed framework provides a generalised routine for establishing anisotropic creep-ageing models for various 2xxx aluminium alloys.2xxx铝合金由于其轻质和平衡的性能特点而广泛应用于航空航天工业。然而,对于2xxx铝合金的各向异性蠕变变形和蠕变时效成形(CAF)强化行为的综合建模方法仍然缺乏。本文提出了建立本构模型的广义框架,该模型能够描述原始和预变形2xxx系列铝合金在蠕变时效过程中的各向异性蠕变变形、微观组织和材料强度演变。该框架通过采用非均匀有理b样条(NURBS),将基于轧制方向的材料模型扩展到加载方向和轧制方向之间不同角度的各向异性场景。详细介绍了各向异性模型的标定和数值模拟实现。通过本构建模和数值模拟,将该方法应用于预变形和不预变形的各种2xxx系列铝合金,验证了该方法的可行性,预测结果与实验数据吻合良好。提出的框架首次为建立各种2xxx铝合金的各向异性蠕变时效模型提供了一个通用的程序。Thin-Walled StructuresDelamination free forming of novel high interface strength metal-polymer laminatesR.K. Naik, S.K. Panda, V. Racherladoi:10.1016/j.tws.2024.112416 新型高界面强度金属-聚合物层压板的无分层成形A new class of metal-polymer-laminates, fabricated using wire mesh and “steel-chips” interlayer, is shown to have significantly high interface strength. A finite element model, calibrated using tensile, lap shear, and peel tests, is used to predict the deformation and failure of the laminates. Formability of the developed laminates is studied using the limiting-dome-height tests. The metal-polymer-laminates do not delaminate in any of the tests. A complete shift of forming-limit-curve towards biaxial-tension region is observed in strain-based forming limit diagram for the polymer side. Strain-path independent forming-limits are plotted in stress space, to negative the effect of non-proportional strain histories.一种新型的金属-聚合物层压板,由金属丝网和“钢屑”夹层制成,具有显著的高界面强度。使用拉伸、搭接剪切和剥离试验校准的有限元模型,用于预测层压板的变形和失效。利用极限顶高试验对所研制的层合板的成形性进行了研究。金属聚合物层压板在任何测试中都不会分层。在基于应变的聚合物侧成形极限图中,成形极限曲线完全向双轴拉伸区移动。在应力空间中绘制了与应变路径无关的形成极限,以消除非比例应变历史的影响。Regression-classification ensemble machine learning model for loading capacity and bucking mode prediction of cold-formed steel built-up I-section columnsYan Lu, Bin Wu, Wenchao Li, Tianhua Zhou, Yanchun Lidoi:10.1016/j.tws.2024.112427冷弯型钢组合截面柱承载力及屈曲模态预测的回归分类集成机器学习模型This paper presents a regression-classification ensemble machine learning (ML) model for load capacity and, in particular, buckling mode prediction with respect to cold-formed steel (CFS) I-section columns. The ML model comprises two sub-models, including the regression sub-model for load capacity prediction and the classification sub-model for buckling mode prediction. A total of 541 experimental and numerical data for CFS built-up I-section columns with varies geometric dimensions, material properties and buckling modes were collected from the literature to construct a dataset. To improve the accuracy and the explainability of the ML model on relative small-scale dataset, physical information-enhanced features based on the knowledge of the direct strength method were adopted as the input features of the ML model, including the yield strength, the elastic local buckling load, the elastic distortional buckling load and the elastic global buckling load, instead of directly using the parameters of geometric dimensions and material properties as the input features. The appropriateness of seven classical machine learning algorithms was compared, namely Decision Tree (DT), Random Forest (RF), Support Vector Machine (SVM), K-Nearest Neighbour (KNN), Adaptive Boosting (ADA), Extreme Gradient Boosting (XG), and Categorical Boosting (CB). The statistical analysis showed that the XG algorithm had the highest level of accuracy for both loading capacity and buckling mode prediction. In addition, the explainability analysis indicated that the developed ML model successfully learned the mechanical characteristic of CFS built-up I-section columns. Finally, the developed ML model was further compared with the existing codified method in the literature. The comparison results indicated that the developed ML model can significantly improve the level of accuracy for loading capacity and buckling mode prediction, which provides a promising alternative choice for the design of CFS built-up I-section columns本文提出了一个回归分类集成机器学习(ML)模型,用于承载能力,特别是关于冷弯型钢(CFS) i型截面柱的屈曲模式预测。ML模型包括两个子模型,分别是用于载荷能力预测的回归子模型和用于屈曲模态预测的分类子模型。本文收集了541个不同几何尺寸、材料性能和屈曲模态的CFS组合式工字截面柱的实验和数值数据,构建了数据集。为了提高ML模型在相对小尺度数据集上的准确性和可解释性,采用基于直接强度法知识的物理信息增强特征作为ML模型的输入特征,包括屈服强度、弹性局部屈曲载荷、弹性畸变屈曲载荷和弹性全局屈曲载荷,而不是直接使用几何尺寸和材料性能参数作为ML模型的输入特征。比较了决策树(DT)、随机森林(RF)、支持向量机(SVM)、k近邻(KNN)、自适应增强(ADA)、极端梯度增强(XG)和分类增强(CB)等7种经典机器学习算法的适用性。统计分析表明,XG算法对载荷能力和屈曲模态的预测精度最高。此外,可解释性分析表明,所建立的ML模型成功地学习了CFS组合工字截面柱的力学特性。最后,将所建立的机器学习模型与文献中已有的编码方法进行了进一步的比较。结果表明,所建立的ML模型能显著提高承载能力和屈曲模态预测的精度水平,为组合式工字截面柱的设计提供了一种有希望的替代选择A CO-HSDT isogeometric analysis for free vibration of matrix cracked FG-GPLRC plates coupled with stationary fluidWei Chen, Linxin Peng, Bing Sun, Wanruo Chen, Yaochu Fangdoi:10.1016/j.tws.2024.112441静止流体耦合下FG-GPLRC基体裂纹板自由振动的CO-HSDT等几何分析This paper for the first time proposes an efficiently C0-higer order shear deformation theory (HSDT) and isogeometric analysis (IGA) for the free vibration analysis of matrix cracked functionally graphene nanoplatelets reinforced composite (FG-GPLRC) plate coupled with stationary fluid. This case represents essential components of sophisticated structures utilized in industries such as shipbuilding, nuclear, marine, and naval. The properties of the four GPLs distributions of FG-GPLRC are evaluated by using a combination of the modified Halpin-Tsai micromechanics model and the rule of mixtures, while the degraded stiffness of cracked layers is predicted by the self-consistent micromechanical (SCM) model. The fluid is assumed to be homogeneous, inviscid, incompressible and irrotational, so the free-surface waves and hydrostatic pressure effects on structures are neglected. The governing equation of motion is derived by the Hamilton's principle, where three different fluid-plate interaction systems are taken into consideration. After validating the proposed method against existing literature, the effect of various parameters such as crack density, interaction boundary conditions (IBC), fluid level, GPLs distribution pattern, total number of layers, and geometric parameter on the free vibration of matrix cracked FG-GPLRC plate are investigated. It is believed that the finding in this paper may be helpful for the accurate design and analysis of matrix cracked FG-GPLRC plate submerged in fluid.本文首次提出了一种高效的c0 -高阶剪切变形理论(HSDT)和等几何分析(IGA),用于分析固定流体耦合下的基体裂纹功能石墨烯纳米片增强复合材料(FG-GPLRC)板的自由振动。这个案例代表了在造船、核、海洋和海军等行业中使用的复杂结构的重要组成部分。采用改进的Halpin-Tsai细观力学模型和混合规律对FG-GPLRC的四种GPLs分布特性进行了评价,并采用自洽细观力学模型对裂纹层的退化刚度进行了预测。假设流体是均匀的、无粘的、不可压缩的和无旋转的,因此忽略了自由表面波和静水压力对结构的影响。在考虑了三种不同的流-板相互作用系统的情况下,利用汉密尔顿原理推导了运动控制方程。在对照已有文献验证该方法的基础上,研究了裂纹密度、相互作用边界条件(IBC)、流体水平、gpl分布模式、层数和几何参数等参数对基体裂纹FG-GPLRC板自由振动的影响。本文的研究结果可为基体裂纹FG-GPLRC板在流体中的精确设计和分析提供参考。Impact Behavior of Advanced Films under Micro- and Nano-scales: A ReviewYujie Cheng, Jinlei Dong, Kailu Xiao, Minqiang Jiang, Chenguang Huang, Xianqian Wudoi:10.1016/j.tws.2024.112443先进薄膜在微纳米尺度下的冲击行为研究进展High-performance materials with excellent impact resistance are of fundamental importance in impact protective engineering. With the development of experimental facilities and numerical simulations at the micro- and nano-scales in recent years, some advanced films are found to show extraordinary energy absorption capacities, showing great promise as ideal bulletproof materials. In this paper, we review the dynamic behavior of four typical types of advanced films that are promising candidates as bulletproof materials subject to supersonic micro- and nano-ballistic impact. Their specific energy absorptions are summarized and the corresponding energy dissipation mechanisms are provided. The size effects are discussed. Some feasible design strategies for improving the impact resistance of the films are also introduced. It should be noted the current ballistic impact standards such as the NIJ standard do not apply to nanofilms. Based on LIPIT and MD simulations, the protective properties of the nanofilms have been obtained. We think that if the materials show high SEAs under micro- and nano-ballistic impact, they are expected to exhibit high impact resistance at the macro scale.具有优异抗冲击性能的高性能材料是冲击防护工程的基础。近年来,随着实验设备的发展和在微纳米尺度上的数值模拟,一些先进的薄膜显示出非凡的能量吸收能力,有望成为理想的防弹材料。在本文中,我们回顾了四种典型的有希望成为防弹材料的先进薄膜在超音速微纳米弹道冲击下的动态行为。总结了它们的比能量吸收,并给出了相应的能量耗散机制。讨论了尺寸效应。介绍了提高薄膜抗冲击性能的可行设计策略。应该指出的是,目前的弹道冲击标准,如NIJ标准,并不适用于纳米膜。基于LIPIT和MD模拟,得到了纳米膜的保护性能。我们认为,如果材料在微观和纳米弹道冲击下表现出较高的SEAs,则有望在宏观尺度上表现出较高的抗冲击性。来源:复合材料力学仿真Composites FEM

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