今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 2 篇,Thin-Walled Structures 4 篇
Modelling the magnetic-mechanical coupled viscoelastic behaviour of transversely isotropic soft magnetorheological elastomers
Bochao Wang, Leif Kari, Huaxia Deng, Xinglong Gong
doi:10.1016/j.ijsolstr.2024.112863
横向各向同性软磁流变弹性体的磁-力耦合粘弹性行为建模
Soft magnetorheological elastomers (s-MRE) is a kind of smart material mainly fabricated by embedding soft magnetic particles into an elastomer matrix. It can be categorized as isotropic and transversely isotropic, depending on the arrangement of internal magnetic particles. In isotropic s-MRE, magnetic particles are randomly distributed, while transversely isotropic s-MRE forms chain structures for the magnetic particles. Compared with isotropic s-MRE, transversely isotropic s-MRE exhibits more significant magnetically-enhanced mechanical properties, making it highly applicable in the vibration control area. While past theoretical work has mainly focused on the magneto-mechanical coupling behaviour of isotropic s-MRE, less attention has been given to modelling the magneto-mechanical coupling behaviour of transversely isotropic s-MRE. Specifically, understanding the impact of different particle chain-magnetic field spatial locations on the magnetization and magnetic-enhanced viscoelastic behaviour of transversely isotropic s-MRE remains an open topic. To address this research gap, we characterize the quasi-static, viscoelastic and magnetization performance of transversely isotropic s-MRE under different particle chain-magnetic field spatial locations. Subsequently, we develop a novel constitutive model for transversely isotropic s-MRE, integrating magneto-hyperelasticity, magneto-viscoelasticity and magnetization. We then implement the magneto-mechanical coupled model for transversely isotropic s-MRE at a finite element level. Following model calibration and validation, we conduct a case study to demonstrate the model’s ability to predict the magneto-mechanical coupling performance of a transversely isotropic s-MRE-based laminated isolator. This model is a valuable tool for predicting the magneto-mechanical performance of transversely isotropic s-MRE-based smart devices, thereby facilitating the design and advancement of transversely isotropic s-MRE in vibration control.
软磁流变弹性体(s-MRE)是一种主要通过在弹性体基体中嵌入软磁微粒而制备的智能材料。根据内部磁粒子的排列,它可以分为各向同性和横向各向同性。在各向同性s-MRE中,磁性颗粒是随机分布的,而横向各向同性s-MRE中磁性颗粒形成链状结构。与各向同性s-MRE相比,横向各向同性s-MRE表现出更显著的磁增强力学性能,在振动控制领域具有很高的应用价值。过去的理论工作主要集中在各向同性s-MRE的磁-力耦合行为上,而对横向各向同性s-MRE的磁-力耦合行为的建模关注较少。具体来说,了解不同粒子链磁场空间位置对横向各向同性s-MRE磁化和磁增强粘弹性行为的影响仍然是一个开放的话题。为了解决这一研究空白,我们对不同粒子链磁场空间位置下横各向同性s-MRE的准静态、粘弹性和磁化性能进行了表征。随后,我们建立了一个新的横向各向同性s-MRE本构模型,将磁-超弹性、磁-粘弹性和磁化相结合。然后,我们在有限元水平上实现了横向各向同性s-MRE的磁-力耦合模型。在模型校准和验证之后,我们进行了一个案例研究,以证明该模型能够预测基于横向各向同性s- mre的层压隔离器的磁-力耦合性能。该模型为预测基于横各向同性s-MRE的智能设备的磁力学性能提供了有价值的工具,从而为横各向同性s-MRE在振动控制中的设计和推进提供了便利。
Interlocked wood-like composites with tunable mechanical properties
Hui Liu, Xu Wang, Lei Wan, Juan Hao, Yujie Zhong, Zhengyi Mao, Heyi Wang, Zhaowenbo Cao, Shaogang Wang, Jian Lu
doi:10.1016/j.jmps.2024.105679
具有可调机械性能的互锁类木复合材料
Inspired by the fact that the architecture of natural biomaterials has a great influence on their mechanical properties, the present work designed a Al2O3–poly (methyl methacrylate) composite with an interlocked wood-like architecture, which can balance the contradictions between flexural strength–fracture toughness. The results shows that the mechanical performance of the composites can be tuned through the adjustment of the tilt angle of the Al2O3 spiral fibres. The composite with a tilt angle of 30° exhibited the highest flexural strength and fracture toughness, showing the ability to overcome the trade-off between flexural strength and fracture toughness. All composites exhibited weak compressive strength anisotropy owing to the interlocked helical architecture in which the continuous fiber spiraled in 3D space. Toughening mechanisms including crack deflection, crack bridging, crack bifurcation, microcracking were observed. Numerous microcracks were nucleated in the Al2O3 ceramic skeleton, and they propagated along the main crack under the bridging effect of poly (methyl methacrylate). All of the composites featured suture-like cracks perpendicular to the direction of the main cracks, which was a unique toughening mechanism found in this architecture. Large-size composites can be prepared through the adopted technique to meet the demands of engineering applications.
受天然生物材料的结构对其力学性能影响很大的启发,本工作设计了一种具有连锁木状结构的al2o3 -聚甲基丙烯酸甲酯复合材料,可以平衡弯曲强度与断裂韧性之间的矛盾。结果表明,通过调整Al2O3螺旋纤维的倾斜角度可以调节复合材料的力学性能。倾角为30°的复合材料具有最高的抗弯强度和断裂韧性,显示出克服抗弯强度和断裂韧性之间权衡的能力。所有复合材料的抗压强度各向异性都较弱,这是由于连续纤维在三维空间中螺旋缠绕的连锁螺旋结构造成的。观察了裂纹挠曲、裂纹桥接、裂纹分岔和微裂纹等增韧机制。在Al2O3陶瓷骨架中形成大量微裂纹,并在聚甲基丙烯酸甲酯的桥接作用下沿主裂纹扩展。所有复合材料都具有垂直于主裂纹方向的缝合线状裂纹,这是该结构中发现的一种独特的增韧机制。采用该技术可制备大尺寸复合材料,满足工程应用的需要。
Cracking of Soft Collagenous Tissues under Suture Retention
Jingda Tang, Jiayi Lin, Tiejun Wang
doi:10.1016/j.jmps.2024.105682
缝线保留下软胶原组织开裂
Soft collagenous tissues consist of collagen fibers and soft matrix, such as skin, muscle, and heart valve, etc. Suture of the tissues is ubiquitous in surgery, which may cause fracture of tissues due to inevitably introduced defects. However, the cracking mechanism of soft collagenous tissues under suture retention remains elusive. Herein, we use bovine pericardium as a model tissue to study the suture related fracture considering various fiber orientations. Fracture tests reveal distinct toughness and fracture modes of the tissue depending on the fiber orientation, such as crack propagation and crack deflection. The maximum J-integral criterion has been established to predict the direction of crack propagation in the tissue. We further conduct suture retention test to evaluate the suture resistance of tissues, and find two different failure modes: fracture and cutting. Microscopic examination of the fracture surface demonstrates that the tissue can rupture with long fiber pullout, cut through matrix failure, or cut by a combination of fiber break and pullout. The cohesive element model is used to analyze the cutting mode. The predicted failure modes and force-displacement curves match well with experiments. This paper may provide guidance to surgical operations and benefit new artificial collagenous materials.
软胶原组织由胶原纤维和软基质组成,如皮肤、肌肉、心脏瓣膜等。手术中组织缝合无处不在,不可避免地会引入缺陷,导致组织断裂。然而,软胶原组织在缝线保留下的开裂机制尚不清楚。在此,我们以牛心包为模型组织,考虑不同的纤维取向来研究与缝合线相关的骨折。断裂试验揭示了不同纤维取向的组织的不同韧性和断裂模式,如裂纹扩展和裂纹挠曲。建立了最大j积分准则来预测裂纹在组织中的扩展方向。我们进一步进行缝合保留试验,评估组织的缝合阻力,发现两种不同的破坏模式:断裂和切割。断口表面的显微检查表明,组织可因长纤维拉出而破裂,可因基质破坏而切割,或因纤维断裂和拉出而切割。采用内聚元模型对切削模式进行分析。预测的破坏模式和力-位移曲线与试验结果吻合较好。本文可为外科手术提供指导,并有利于新型人工胶原材料的开发。
Initial load factor adjustment through genetic algorithm for the generalized displacement control method: Implementation on non-rigid origami analysis
Ali Maghami, Seyed Mahmoud Hosseini
doi:10.1016/j.tws.2024.111972
基于遗传算法的初始载荷因子调整广义位移控制方法:在非刚性折纸分析中的实现
The nonlinear analysis of structural systems relies on effective nonlinear solution schemes, known as nonlinear solvers or path-following methods. This paper explores the challenge of determining the initial load factor in such analyses, with a particular focus on complex origami structures. This study presents a novel approach that leverages genetic algorithms (GA) to efficiently determine the initial load factor for the generalized displacement method. Building upon the concept of stiffness parameters, our method offers a systematic solution. In this work, GA serves as a tool to discover the appropriate initial load factor based on changes in the stiffness parameter, providing a more rational and user-friendly approach. To demonstrate the practical applicability of our approach, we apply it to a range of complex origami problems, including the folding of Miura-ori, folding of an egg-box origami, bending of an egg-box origami, and folding of an arc Miura-ori. These examples, along with a truss example, encompass highly nonlinear behaviors, including limit points, extreme stiffness fluctuations, snap-through, and snap-back. Our results showcase the effectiveness of our method in accurately tuning the initial load factor to capture and track intricate nonlinear behaviors. Furthermore, it offers the flexibility to fine-tune the distribution of points along the path and manage the resolution of the depicted equilibrium path. This versatility underscores its potential applications in fields such as deployable structures and complex large deformation structural analysis.
结构系统的非线性分析依赖于有效的非线性解方案,即非线性求解器或路径跟踪方法。本文探讨了在这种分析中确定初始载荷因子的挑战,特别关注复杂的折纸结构。本文提出了一种利用遗传算法有效确定广义位移法初始载荷因子的新方法。基于刚度参数的概念,我们的方法提供了一个系统的解决方案。在这项工作中,遗传算法作为一种工具,根据刚度参数的变化发现适当的初始载荷因子,提供了一种更合理和用户友好的方法。为了证明我们的方法的实际适用性,我们将其应用于一系列复杂的折纸问题,包括Miura-ori的折叠,蛋盒折纸的折叠,蛋盒折纸的弯曲,以及弧Miura-ori的折叠。这些示例以及桁架示例包含高度非线性行为,包括极限点、极端刚度波动、跳穿和跳回。我们的结果显示了我们的方法在精确调整初始负载因子以捕获和跟踪复杂的非线性行为方面的有效性。此外,它还提供了沿路径微调点分布的灵活性,并管理所描述的平衡路径的分辨率。这种多功能性强调了其在可展开结构和复杂大变形结构分析等领域的潜在应用。
Geometry-force interactive design and optimization method of cable dome structures
Suduo Xue, Xuanzhi Li, Xiongyan Li
doi:10.1016/j.tws.2024.111977
索穹顶结构几何-力交互设计及优化方法
Cable dome is a typical flexible structural system. Its initial geometry determines the prestress distribution and affects the structural performance. Using geometric parameters to establish the mechanical equation of initial state can effectively realize the geometric-force interactive design and optimization of cable dome structure. Consequently, a standardized equation is established in this paper to uniformly express the geometric-force relationship, utilizing a feasible prestress distribution function expressed by geometric parameters. Subsequently, an interactive design method for initial geometry and prestress is presented. The proposed method is theoretically expounded in terms of geometric design, prestress design and shape optimization. Two typical cable dome cases, Geiger and Levy, are successfully applied to accomplish the geometric-force design and optimization of the initial state. The results show that the efficient design of initial state can be completed by establishing the interaction between geometry and force without repeated algebraic calculation. The optimized initial geometry can significantly improve the Structural stiffness.
索穹顶是一种典型的柔性结构体系。其初始几何形状决定了预应力分布,影响结构性能。利用几何参数建立初始状态力学方程,可以有效地实现索穹顶结构的几何-力交互设计与优化。因此,本文利用可行的几何参数表示的预应力分布函数,建立了统一表示几何-力关系的标准化方程。在此基础上,提出了初始几何与预应力的交互设计方法。从几何设计、预应力设计和形状优化三个方面对该方法进行了理论阐述。采用Geiger和Levy两种典型的索穹顶案例,成功地完成了初始状态的几何力设计和优化。结果表明,通过建立几何与力之间的相互作用,无需重复代数计算,即可完成初始状态的有效设计。优化后的初始几何形状能显著提高结构刚度。
A generalizable framework of solution-guided machine learning with application to nanoindentation of free-standing thin films
Ruijin Wang, Tianquan Ying, Yang Chen, Fangyan Zhu, Jiantao Leng, Tienchong Chang, Tongyi Zhang, Huajian Gao
doi:10.1016/j.tws.2024.111984
求解导向机器学习的通用框架及其在独立薄膜纳米压痕中的应用
Despite the significant success of machine learning (ML) in various fields, there remains a critical need to enhance its ability to extrapolate from insufficient data. Here, we propose a generalizable framework called solution-guided machine learning (SGML), which integrates existing solutions as additional features to supplement limited training data. Our application of SGML to nanoindentation of free-standing thin films demonstrates robust performance, including good training convergence, accuracy, and extrapolation. Notably, the SGML models trained on limited data are able to be applied across a wider range of scenarios, e.g., the model trained on relatively moderate indenter sizes applies to relatively small as well as large indenter sizes, and the model trained for graphene successfully extends its applicability to other 2D nanomaterials (e.g., MoS2) and even to microscale thin films (e.g., silicone), highlighting extraordinary extrapolation performance. We discuss also the cooperative relationship between solutions and data, further confirming that the enhanced performance of SGML is attributed to the complementary information supplemented by solutions to data. This work presents a robust method to train more powerful ML models by combining known knowledge with limited data, offering great potential for addressing complex problems that often suffer from data insufficiency.
尽管机器学习(ML)在各个领域取得了重大成功,但仍然迫切需要增强其从不足数据中推断的能力。在这里,我们提出了一个可推广的框架,称为解决方案引导机器学习(SGML),它将现有的解决方案集成为附加特征,以补充有限的训练数据。我们将SGML应用于独立薄膜的纳米压痕,展示了强大的性能,包括良好的训练收敛性、准确性和外推性。值得注意的是,在有限数据上训练的SGML模型能够应用于更广泛的场景,例如,在相对适中的压头尺寸上训练的模型适用于相对较小和较大的压头尺寸,并且为石墨烯训练的模型成功地将其适用性扩展到其他2D纳米材料(例如MoS2)甚至微尺度薄膜(例如硅胶),突出了非凡的外推性能。我们还讨论了解决方案和数据之间的合作关系,进一步证实了SGML性能的增强归功于解决方案对数据的补充信息。这项工作提出了一种鲁棒的方法,通过将已知知识与有限的数据相结合来训练更强大的ML模型,为解决经常遭受数据不足的复杂问题提供了巨大的潜力。
Energy absorption in expanding metallic wire mesh tubes
Wangfan Zhou, Dora Karagiozova, Xudong Ren, Guoxing Lu
doi:10.1016/j.tws.2024.111981
膨胀金属丝网管的能量吸收
The deformation process and energy absorption of metal wire mesh tubes under quasi-static expanding by a hemispherical-cylindrical indenter were investigated by experimental tests, finite element (FE) simulations and analytical modelling. Stainless steel and aluminum alloy tubes were tested on an MTS universal testing machine at a speed of 10 mm/min. The effects of mesh cell size and friction coefficient on the quasi-static force and specific energy absorption (SEA) were examined by FE analysis and analytical modelling. The analysis reveals that a combination of the mesh cell size and cross section dimension of the wire governs the energy absorption of tubes of equal overall dimension (diameter and length) and masses. In general, a decrease of the size of cells with constant height-to-width ratios leads to an increase of the specific energy absorption mainly due to the increased number of cells within the deformed region. An increase of the specific energy absorption is also achieved when the cell size is reduced by only decreasing the cell height. The maximum indenter force predicted by the proposed analytical model of the expanded tube deformation agrees well with the experimental results and FE simulations.
采用实验试验、有限元模拟和分析模型,研究了金属丝网管在半圆圆柱压头准静态膨胀作用下的变形过程和吸能特性。不锈钢管和铝合金管在MTS万能试验机上以10 mm/min的速度进行测试。通过有限元分析和解析建模,考察了网格尺寸和摩擦系数对准静力和比能吸收(SEA)的影响。分析表明,网孔尺寸和丝的横截面尺寸的组合决定了管的总尺寸(直径和长度)和质量相等的吸能。一般来说,在等高宽比下,减小细胞的尺寸会导致比能量吸收的增加,这主要是由于变形区域内细胞数量的增加。当仅通过降低电池高度来减小电池尺寸时,也实现了比能量吸收的增加。所建立的膨胀管变形分析模型所预测的最大压头力与实验结果和有限元模拟结果吻合较好。