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
Elastic wave propagation in cubic non-centrosymmetric and chiral architectured materials: Insights from strain gradient elasticity
G. Rosi, N. Auffray, C. Combescure
doi: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。
Self-consistent solution of the Frank-Bilby equation for interfaces containing disconnections
David B. Gordon, Ryan B. Sills
doi: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。
A generalised framework for modelling anisotropic creep-ageing deformation and strength evolution of 2xxx aluminium alloys
Xi Wang, Zhusheng Shi, Jianguo Lin
doi:10.1016/j.ijplas.2024.104114
2xxx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。
Delamination free forming of novel high interface strength metal-polymer laminates
R.K. Naik, S.K. Panda, V. Racherla
doi: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 columns
Yan Lu, Bin Wu, Wenchao Li, Tianhua Zhou, Yanchun Li
doi: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 fluid
Wei Chen, Linxin Peng, Bing Sun, Wanruo Chen, Yaochu Fang
doi: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 Review
Yujie Cheng, Jinlei Dong, Kailu Xiao, Minqiang Jiang, Chenguang Huang, Xianqian Wu
doi: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。