今日更新:International Journal of Solids and Structures 2 篇,Journal of the Mechanics and Physics of Solids 1 篇,Thin-Walled Structures 7 篇
FE modeling to generate composite RVEs with high volume fractions and various shapes of inclusions
Wenlong Tian, Yajun Zhang, Chaosong Pei, Jian Ge, Xujiang Chao, Lehua Qi
doi:10.1016/j.ijsolstr.2024.112933
利用有限元建模生成具有高体积分数和各种形状夹杂物的复合 RVE
This work proposes a novel multi-step dynamic FE compression method to generate Representative Volume Elements (RVEs) of composites containing a variety of inclusions. This method is actualized through a sequential and four-stage procedure: (1) Sparse and periodic inclusions exhibiting a predefined orientation distribution are generated by implementing a modified random sequential adsorption algorithm, (2) Sparse inclusions undergo biaxial compression into the region of the targeted RVE via a dynamic FE analysis, (3) Periodic inclusions are compressed into the region utilizing a dynamic FE analysis with periodic boundary conditions, and (4) Positions and orientations of the compressed inclusions are extracted and the RVE in computer-aided design format is then generated. The proposed method confers advantages from four distinct perspectives: (1) applicability to various inclusion geometries, including ellipses, lobules, polygons, kidneys and stars, (2) ability to generate periodic RVEs of composites with high inclusion volume fractions (up to 80.0% for circular inclusions), (3) simple and straightforward numerical implementation without explicitly considering inclusion intersection check and (4) capacity to predefine inclusion orientation distribution. Statistical analyses utilizing multiple spatial descriptors, i.e., inclusion orientation angle, local volume fraction, voronoi cells area, nearest-neighbor distance and orientation, second order intensity function, radial distribution function and two-point probability function, confirm randomness of inclusion distribution in the generated RVEs. The elastic properties and damage behaviors of composites via the FE homogenization method are predicted based on the generated RVEs and are compared with those of available experimental data, the literature and the mean-field homogenization models to demonstrate effectiveness of the proposed multi-step dynamic FE compression method.
本研究提出了一种新颖的多步骤动态有限元压缩方法,用于生成含有各种夹杂物的复合材料的代表体积元素(RVE)。该方法通过一个有序的四阶段程序实现:(1)通过实施修改后的随机顺序吸附算法生成呈现预定方位分布的稀疏和周期性夹杂物;(2)通过动态 FE 分析将稀疏夹杂物双轴压缩到目标 RVE 区域;(3)利用具有周期性边界条件的动态 FE 分析将周期性夹杂物压缩到该区域;以及(4)提取压缩夹杂物的位置和方位,然后生成计算机辅助设计格式的 RVE。所提出的方法从四个不同的角度体现了其优势:(1) 适用于各种夹杂物几何形状,包括椭圆形、小叶形、多边形、肾形和星形;(2) 能够生成具有高夹杂物体积分数(圆形夹杂物高达 80.0%)的复合材料的周期性 RVE;(3) 简单直接的数值实施,无需明确考虑夹杂物交叉检查;(4) 能够预先确定夹杂物的方向分布。利用多种空间描述符(即夹杂物取向角、局部体积分数、Voronoi 单元面积、最近邻距离和取向、二阶强度函数、径向分布函数和两点概率函数)进行的统计分析证实了生成的 RVE 中夹杂物分布的随机性。根据生成的 RVE,通过 FE 均质化方法预测了复合材料的弹性特性和损伤行为,并与现有实验数据、文献和均场均质化模型进行了比较,从而证明了所提出的多步骤动态 FE 压缩方法的有效性。
Improved concept of representative directions: Cluster approach
A.V. Shutov, O.D. Vardosanidze
doi:10.1016/j.ijsolstr.2024.112934
改进代表方向的概念:集群方法
The concept of representative directions is a method for constitutive modelling that generalises uniaxial constitutive equations to the general multiaxial case. The simplicity of the concept allows both novice and experienced users to develop advanced material models, covering a wide range of nonlinear phenomena. This paper introduces the cluster approach, a new version of the concept that operates with clusters of fibres. Similar to the original concept, the cluster approach ensures objectivity and inherits the thermodynamic consistency of uniaxial models. The paper details the computational algorithms and presents numerical tests, highlighting the advantages of the new approach. Due to the smearing of fibres in orientation space, the cluster approach efficiently represents initially isotropic material behaviour with fewer clusters, making it computationally more efficient than the classical concept of representative directions. As a demonstration, the paper shows the adequacy of the cluster approach in capturing the actual inelastic behaviour of certain polymers and metals.
代表方向的概念是一种将单轴构成方程推广到一般多轴情况的构成建模方法。这一概念的简洁性使新手和经验丰富的用户都能开发出涵盖各种非线性现象的高级材料模型。本文介绍了簇方法,这是该概念的一个新版本,使用的是纤维簇。与原始概念类似,集群方法确保了客观性,并继承了单轴模型的热力学一致性。论文详细介绍了计算算法并进行了数值测试,突出强调了新方法的优势。由于纤维在取向空间中的涂抹,聚类方法以较少的聚类有效地表示了初始各向同性材料的行为,使其在计算上比经典的代表方向概念更有效。作为示范,论文展示了聚类方法在捕捉某些聚合物和金属的实际非弹性行为方面的充分性。
Modified error-in-constitutive-relation (MECR) framework for the characterization of linear viscoelastic solids
Marc Bonnet, Prasanna Salasiya, Bojan B. Guzina
doi:10.1016/j.jmps.2024.105746
表征线性粘弹性固体的修正误差-构造相关性(MECR)框架
We develop an error-in-constitutive-relation (ECR) approach toward the full-field characterization of linear viscoelastic solids described within the framework of standard generalized materials. To this end, we formulate the viscoelastic behavior in terms of the (Helmholtz) free energy potential and a dissipation potential. Assuming the availability of full-field interior kinematic data, the constitutive mismatch between the kinematic quantities (strains and internal thermodynamic variables) and their “stress” counterparts (Cauchy stress tensor and that of thermodynamic tensions), commonly referred to as the ECR functional, is established with the aid of Legendre-Fenchel gap functionals linking the thermodynamic potentials to their energetic conjugates. We then proceed by introducing the modified ECR (MECR) functional as a linear combination between its ECR parent and the kinematic data misfit, computed for a trial set of constitutive parameters. The affiliated stationarity conditions then yield two coupled evolution problems, namely (i) the forward evolution problem for the (trial) displacement field driven by the constitutive mismatch, and (ii) the backward evolution problem for the adjoint field driven by the data mismatch. This allows us to establish compact expressions for the MECR functional and its gradient with respect to the viscoelastic constitutive parameters. For generality, the formulation is established assuming both time-domain (i.e. transient) and frequency-domain data. We illustrate the developments in a two-dimensional setting by pursuing the multi-frequency MECR reconstruction of (i) piecewise-homogeneous standard linear solid, and (b) smoothly-varying Jeffreys viscoelastic material.
我们针对在标准通用材料框架内描述的线性粘弹性固体的全场特性,开发了一种构造相关误差(ECR)方法。为此,我们用(亥姆霍兹)自由能势和耗散势来描述粘弹性行为。假设存在全场内部运动学数据,则运动学量(应变和内部热力学变量)与其 "应力 "对应物(考希应力张量和热力学张量)(通常称为 ECR 函数)之间的构成失配将借助 Legendre-Fenchel 间隙函数建立起来,该函数将热力学势能与其能量共轭物联系起来。然后,我们引入修正的 ECR(MECR)函数,将其作为 ECR 母函数与运动学数据失配之间的线性组合,并对一组试验性构成参数进行计算。附属静止条件产生两个耦合演化问题,即 (i) 由构成失配驱动的(试验)位移场的前向演化问题,以及 (ii) 由数据失配驱动的邻接场的后向演化问题。这样,我们就可以建立 MECR 函数及其梯度相对于粘弹性结构参数的紧凑表达式。为通用起见,我们同时假设了时域(即瞬态)和频域数据。我们通过研究 (i) 片状均质标准线性固体和 (b) 平滑变化的 Jeffreys 粘弹性材料的多频 MECR 重构,说明二维环境下的发展情况。
Bandgap tunability and impact mitigation enhancement of hybrid graded origami-inspired metamaterials with multiple resonators
Chunlei Li, Yu Sun, Qiang Han, Tengjiao Jiang
doi:10.1016/j.tws.2024.112137
具有多个谐振器的混合梯度折纸启发超材料的带隙可调性和影响减缓增强功能
Origami structure has become an important design source of metamaterials because of its extremely rich form and infinite design space. In order to improve the wave attenuation and impact mitigation ability of origami structure, a hybrid graded origami-inspired metamaterials with multiple resonators is proposed. The bandgap characteristics, transmission spectrum and impact resistance of the proposed metamaterals are analyzed in detail by numerical simulation. The results show that multiple local resonance mechanisms can open two new bandgaps compared to the single local resonance case, and the bandgap boundary is very sensitive to the dimension of resonance units. In particular, the resonance peaks of the origami metamaterals are substantially weakened due to the presence of dimensional gradients, which allows multiple bandgaps to merge into an ultra-wide bandgap (bandwith up to 8.9kHz), about five times than the original bandwidth. According to the time domain and frequency domain analysis results, it can be found that the amplitude of reaction force is significantly reduced in the bandgap range, and the ultra-wide frequency domain (2.9–10kHz) with sustainable-low peak appears. Moreover, the asymmetry and graded design of unit-cell also affects the ability of dissipate and attenuate wave energy and delay the wave transmission time. In addition, the local-resonant origami metamaterials are fabricated by 3D printing technology, and the experimental results are in good agreement with the numerical simulation results. This study is expected to provide valuable ideas in crashworthiness design and impact wave protection of important equipments.
折纸结构以其极其丰富的形式和无限的设计空间成为超材料的重要设计来源。为了提高折纸结构的波衰减和抗冲击能力,本文提出了一种具有多个谐振器的混合分级折纸启发超材料。通过数值模拟详细分析了所提出的超材料的带隙特性、传输谱和抗冲击性。结果表明,与单局部谐振情况相比,多局部谐振机制可以打开两个新的带隙,而且带隙边界对谐振单元的尺寸非常敏感。特别是,由于尺寸梯度的存在,折纸元胞的共振峰被大大削弱,这使得多个带隙合并成一个超宽带隙(带宽高达 8.9kHz),约为原来带宽的五倍。根据时域和频域分析结果,可以发现反作用力的振幅在带隙范围内明显减小,并出现了具有持续低峰值的超宽频域(2.9-10kHz)。此外,单元单元的不对称和分级设计也影响了波能的耗散和衰减能力,并延迟了波的传输时间。此外,该局部谐振折纸超材料是通过三维打印技术制作的,实验结果与数值模拟结果吻合。这项研究有望为重要设备的防撞设计和冲击波防护提供有价值的思路。
A novel multi-step superposition model for the dispersion analysis of multiaxial prestressed plate-like structures
Xu Zhang, Gang Liu, Lei Chen, Yunxiu Ma, Zehui Zhang, Yuxuan Dong
doi:10.1016/j.tws.2024.112138
用于多轴预应力板状结构分散分析的新型多步叠加模型
Understanding the dispersion characteristics of multi-axial prestressed plate-like structures is crucial for the engineering application of guided wave non-destructive testing. However, existing analytical and semi-analytical models neglect both constitutive and geometric nonlinearities induced by the prestress and require tedious theoretical derivation and coding, which may not achieve accurate predictions. To address these issues, a convenient model based on the multi-step superposition analysis was proposed to investigate the effects of an arbitrary multiaxial prestress on the dispersion characteristics of plate-like structures. The core idea of this model involves introducing an initial configuration to describe the static pre-deformation between undeformed and final states; then, the dynamic wave motion was superimposed on the initial pre-deformation for the eigenfrequency analysis. Additionally, the strain energy density of the hyperelastic material was implanted and set as the relevant variable between the two steps by the inheritance of the solution. This model significantly improved the accuracy compared to the conventional method, as validated through biaxial acoustoelastic experiments. Subsequently, the acoustoelastic responses of the multiaxial prestressed 6061-T6 aluminum plate were investigated. The results reveal that the non-uniform in-plane prestress leads to the coupling of guided wave modes propagating along non-principal directions. Furthermore, the effects induced by multiaxial prestress in the frequency bands with low dispersion could be decomposed into the sum of the effects induced by three uniaxial prestresses with a very small deviation. These results provide new insights into the acoustoelastic behavior and a theoretical basis to optimize the guided wave mode and frequency.
了解多轴预应力板状结构的频散特性对于导波无损检测的工程应用至关重要。然而,现有的分析和半分析模型忽略了预应力引起的构成和几何非线性,需要繁琐的理论推导和编码,可能无法实现准确的预测。针对这些问题,我们提出了一种基于多步叠加分析的便捷模型,用于研究任意多轴预应力对板状结构离散特性的影响。该模型的核心思想是引入初始构型来描述未变形状态和最终状态之间的静态预变形;然后,将动态波运动叠加到初始预变形上进行特征频率分析。此外,还植入了超弹性材料的应变能密度,并通过继承解法将其设置为两步之间的相关变量。通过双轴声弹性实验验证,与传统方法相比,该模型大大提高了精确度。随后,研究了多轴预应力 6061-T6 铝板的声弹性响应。结果表明,非均匀面内预应力导致沿非主要方向传播的导波模式耦合。此外,多轴预应力在低色散频段引起的效应可分解为三个单轴预应力引起的效应之和,且偏差极小。这些结果为声弹行为提供了新的见解,也为优化导波模式和频率提供了理论依据。
Plastic and punching shear strengths of concrete-filled steel tubular gapped K-joints without noding eccentricity under brace axial loading
Fei Xu, Xuhong Zhou, Junbo Chen, Yuhang Wang, Jian Zhao
doi:10.1016/j.tws.2024.112139
支撑轴向荷载下无编码偏心的混凝土填充钢管间隙 K 型接头的塑性和冲切剪切强度
This paper presents a comprehensive investigation, numerically and theoretically, into the structural behaviour and design aspects of concrete-filled steel tubular (CFST) gapped K-joints under brace axial loading. Finite element (FE) models were developed and validated against test results from existing experimental programmes. Based on the validated FE models, influences of geometric parameters and steel material properties on the load-deformation curve, plastic strength, ultimate strength and punching shear stress distribution of CFST K-joints were systematically assessed. In general, the chord diameter-to-thickness ratio 2γ, brace-to-chord diameter ratio β and steel material strength are crucial to the structural behaviour of CFST K-joints, whilst the brace-to-chord thickness ratio τ was found to have minimal influence. A shear stress distribution model was proposed as well to predict the shear stress distribution at ultimate load. To accurately account for the radial support of inner concrete, the classical ring model was modified accordingly. Based on the proposed shear stress distribution model and modified ring model, analysis-orientated and design-orientated equations were formulated to estimate both the plastic and ultimate strengths of CFST K-joints. The calculated plastic and ultimate strengths were compared against the experimental and numerical results, and the comparison demonstrates the ability of the proposed design methods to accurately and reliably determine the plastic and ultimate strengths of CFST K joints.
本文从数值和理论两方面全面研究了混凝土填充钢管(CFST)间隙 K 型接头在支撑轴向荷载作用下的结构行为和设计问题。我们开发了有限元(FE)模型,并根据现有实验项目的测试结果进行了验证。根据验证后的有限元模型,系统地评估了几何参数和钢材料特性对 CFST K 型接头的载荷-变形曲线、塑性强度、极限强度和冲剪应力分布的影响。总体而言,弦线直径与厚度比 2γ、支撑与弦线直径比 β 和钢材料强度对 CFST K 型接头的结构行为至关重要,而支撑与弦线厚度比 τ 的影响则微乎其微。此外,还提出了一个剪应力分布模型,用于预测极限载荷下的剪应力分布。为了准确考虑内部混凝土的径向支撑,对经典的环形模型进行了相应的修改。根据提出的剪应力分布模型和修改后的环形模型,制定了面向分析和面向设计的方程,以估算 CFST K 型接头的塑性强度和极限强度。计算得出的塑性强度和极限强度与实验结果和数值结果进行了对比,对比结果表明所提出的设计方法能够准确可靠地确定 CFST K 接头的塑性强度和极限强度。
Optimizing profiled ring preforms for enhanced deformation uniformity using the isothermal field method
Yan Han, Menghan Wang, Hai Su, Yu He, Yuanyuan Zheng, Xin Li
doi:10.1016/j.tws.2024.112140
利用等温场法优化异型环形预成型件以提高变形均匀性
One of the main challenges faced by the profiled ring rolling (PRR) process is to ensure the deformation uniformity of the ring, which is closely related to the design of the ring preform. The paper explores the application of the isothermal field method (IFM) in designing preforms for PRR processes, targeting the aerospace sector's high-end equipment manufacturing. Through the integration of advanced computational models and practical design principles, a comprehensive approach involving IFM, finite element simulation, support vector machine modeling, and genetic algorithm optimization is employed to determine the geometric dimensions of rational preforms. The material flow behavior during the PRR process is analyzed, and the effects of different isotherms combinations on strain, stress and temperature distribution are discussed. The findings demonstrate that adjusting the preform's shape during the section forming stage can optimize the uniformity of strain, stress, and temperature within the forging. The stable ring rolling process revealed no macroscopic or microscopic defects, validating the design method of ring preform based on IFM is reasonable. The research contributes to advancing near-net shape forming technologies, offering a novel approach to preform design that marries theoretical analysis with practical manufacturability considerations.
异型环轧制(PRR)工艺面临的主要挑战之一是确保环的变形均匀性,这与环形预型件的设计密切相关。本文针对航空航天领域的高端装备制造,探讨了等温场法(IFM)在 PRR 工艺预型件设计中的应用。通过整合先进的计算模型和实用的设计原则,采用了一种涉及等温场法、有限元模拟、支持向量机建模和遗传算法优化的综合方法来确定合理预型件的几何尺寸。分析了 PRR 过程中的材料流动行为,并讨论了不同等温线组合对应变、应力和温度分布的影响。研究结果表明,在断面成形阶段调整预型件的形状可以优化锻件内部应变、应力和温度的均匀性。稳定的环形轧制过程没有发现宏观或微观缺陷,验证了基于 IFM 的环形预型件设计方法是合理的。这项研究为推进近净成形技术做出了贡献,提供了一种将理论分析与实际可制造性考虑相结合的新型预型件设计方法。
Experimental and numerical characterization of column webs/faces loaded out-of-plane in steel joints
Melaku Seyoum Lemma, Carlos Rebelo, Jorge Conde Conde, Luís Simões da Silva
doi:10.1016/j.tws.2024.112141
钢接头平面外加载的柱腹板/面的实验和数值特性分析
This paper presents a comprehensive investigation into the behavior of column webs/faces under out-of-plane loading within steel joints. The experimental component of the study involves testing five profiles, encompassing both open and closed sections with varying web slenderness and steel grade, subjected to direct out-of-plane tensile loads through bolted connections, utilizing both single and double rows of bolts. Concurrently, numerical simulations are conducted using finite element models, thoroughly calibrated with the experimental results. Drawing upon the calibrated numerical models, the paper systematically explores the influence of key parameters, including web slenderness, bolt arrangement, and analysis methods, through a parametric study involving 167 cases. A careful comparison of the observed behavior of the component from experimental tests, numerical models, and analytical models for initial stiffness is presented. Finally, the initial stiffness formulation derived from a recent model developed by the authors is improved to align with the observations from the experimental and numerical results.
本文介绍了对钢接头内平面外荷载作用下柱腹板/面的行为的全面研究。研究的实验部分包括测试五种型材,其中既有开放式型材,也有封闭式型材,它们的腹板细长度和钢材等级各不相同,通过螺栓连接(使用单排和双排螺栓)直接承受平面外拉伸荷载。同时,使用有限元模型进行了数值模拟,并根据实验结果进行了全面校准。利用校准后的数值模型,论文通过涉及 167 个案例的参数研究,系统地探讨了关键参数的影响,包括腹板细长度、螺栓布置和分析方法。论文仔细比较了从实验测试、数值模型和初始刚度分析模型中观察到的构件行为。最后,对作者最近开发的模型中得出的初始刚度公式进行了改进,使其与实验和数值结果中的观测结果保持一致。
Dynamic response of thin plate with damping subjected to in-plane compressive harmonic excitation
P. Perlikowski, M. Bohlooly Fotovat, T. Kubiak
doi:10.1016/j.tws.2024.112130
带阻尼薄板在平面压缩谐波激励下的动态响应
The dynamics of a rectangular plate with initial deflection excited by an external force comprising two components, a constant and periodically varying term, were analyzed by the authors of the paper. It was noted that the plate’s initial deflection was perpendicular to its surface, resulting in asymmetry. The partial differential equation governing the plate’s behaviour was simplified to the one-degree-of-freedom Mathieu equation. The three methods have been used to analyze the system’s dynamics: the FEM, the sampled-based method and path-following. The equivalence of the full model with the reduced one was confirmed by the researchers. It was found that the Mathieu equation was suitable for investigating the dynamics of the rectangular plate across various parameters and for studying the sensitivity to initial conditions. It is shown that the reduced model is very efficient for detecting ranges of multistability and bifurcations sequence. A good agreement is also observed for values of stress obtained from full and reduced models.
论文作者分析了一个矩形板在恒定和周期变化两个分量的外力作用下初始偏转的动力学特性。作者注意到,板的初始挠度与其表面垂直,从而导致不对称。指导板块行为的偏微分方程被简化为一自由度马修方程。分析系统动力学时使用了三种方法:有限元法、基于采样的方法和路径跟踪法。研究人员确认了完整模型与简化模型的等价性。研究发现,马修方程适用于研究矩形板在不同参数下的动力学,也适用于研究对初始条件的敏感性。研究表明,简化模型在检测多稳定性范围和分岔序列方面非常有效。从完整模型和简化模型中获得的应力值也有很好的一致性。
Experiments on the material and stability performance of slender WAAM plated structures
Sian I. Evans, Fangda Xu, Jie Wang
doi:10.1016/j.tws.2024.112136
细长 WAAM 镀层结构的材料和稳定性能实验
An experimental study has been carried out to investigate the material and stability performance of WAAM 316L stainless steel plates supported along both edges. The experiments were facilitated by testing a series of square hollow section (SHS) stub columns and tensile coupons extracted from the plates manufactured along with the stub columns. The tensile test results provided the material properties to be used for later analysis of the stub column tests, and indicated anisotropic material behaviour while displaying satisfactory material ductility. The SHS stub column dimensions fall in the range of ‘slender’ cross-sections as defined by Eurocode 3. Their geometric profiles were 3D laser scanned and analysed prior to the compression tests. The failure modes and load carrying capacities of the WAAM SHS stub columns were analysed and compared to the specimens in previous similar studies. The use of the Effective Width Equation in Eurocode 3 and the Continuous Strength Method for the design of slender WAAM stainless steel plates are evaluated.
为了研究 WAAM 316L 不锈钢板两边支撑的材料和稳定性能,我们进行了一项实验研究。通过测试一系列方形空心截面 (SHS) 存根柱和从与存根柱一起制造的钢板中提取的拉伸试样,为实验提供了便利。拉伸测试结果提供了材料特性,用于随后的存根柱测试分析,并显示了各向异性的材料行为,同时显示了令人满意的材料延展性。SHS 存根柱的尺寸属于欧洲规范 3 所定义的 "细长 "截面范围。在压缩试验之前,对其几何轮廓进行了三维激光扫描和分析。对 WAAM SHS 存根柱的破坏模式和承载能力进行了分析,并与之前类似研究中的试样进行了比较。评估了欧洲规范 3 中有效宽度方程和连续强度法在细长 WAAM 不锈钢板设计中的应用。