今日更新:International Journal of Solids and Structures 2 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 2 篇,Thin-Walled Structures 4 篇
Isotropic and orthotropic mechanical properties of in vivo mandible model: Assessment of computational modelling
C.T.M. Anflor, E.D.M. Santanna, F.F.A.O. Nascimento, J.N.V. Goulart
doi:10.1016/j.ijsolstr.2024.112875
体内下颌骨模型的各向同性和正交异性力学性能:计算模型的评估
This study assesses the various methodologies utilized in the literature for computational mandible modeling and their implications on research findings. Previous studies have explored diverse material properties for the mandible, whether modeled as a single entity, in pairs, or as multiple sub-regions. Within this framework, a finite element model of an intact mandible was created using sliced tomographic images to examine the dispersion of stress fields resulting from different sets of bone material properties sourced from specialized literature. This research introduces the methodology employed in mandible model development, strategies for achieving high precision, and the influence of mechanical properties. Through an evaluation of models proposed by different authors, significant dispersion was observed, leading to disparities ranging from 4.4% to 67.4% in stress field outcomes at the symphysis region. RMSE served as an estimator to assess the similarity between these models. The findings suggest that the Caraveo (2008) and Palka (2020) models exhibit notable convergence in predicting stress fields in the symphysis regions. By incorporating good modeling practices in the intact mandible model, a more reliable representation is ensured, laying the groundwork for future investigations involving nonlinear contact phenomena and topology optimization.
本研究评估了文献中用于计算下颌骨建模的各种方法及其对研究结果的影响。以前的研究已经探索了下颌骨的不同材料特性,无论是作为单个实体,成对还是作为多个子区域建模。在此框架内,利用断层扫描图像创建了完整下颌骨的有限元模型,以检查来自专业文献的不同骨材料特性所产生的应力场的分散。本研究介绍了下颌骨模型开发的方法、实现高精度的策略以及力学性能的影响。通过对不同作者提出的模型的评估,观察到显著的分散性,导致联合区应力场结果的差异从4.4%到67.4%不等。RMSE用作评估这些模型之间相似性的估计量。研究结果表明,Caraveo(2008)和Palka(2020)模型在预测联合区应力场方面表现出显著的收敛性。通过将良好的建模实践结合到完整的下颌骨模型中,确保了更可靠的表示,为未来涉及非线性接触现象和拓扑优化的研究奠定了基础。
Deformation in the wrinkle–crease transformation
Tatsuya Ishida, Seishiro Matsubara, So Nagashima, Dai Okumura
doi:10.1016/j.ijsolstr.2024.112876
褶皱-折痕转换中的变形
We investigate deformation in the wrinkle–crease transformation to reveal the missing link between the wrinkling and creasing instabilities, which occur on the surface of elastomers under compression. Plane-strain finite element (FE) analysis is performed by combining a nonlinear perturbation approach to find two bifurcated solutions for the flat surface in a metastable state. The first solution is the stable deformation path for crease evolution, and the second solution is the previously unknown unstable deformation path from wrinkling to creasing. The two deformation paths are not independent, and they are connected at the critical strain for creasing εC. The resulting deformation at εC acts as a precursive deformation to cause creasing. Although the unstable path is initiated by the wrinkling instability as a bifurcation, the creasing instability (i.e., εC) is interpreted as the singular point at which the unstable path switches to the stable path. A chain reaction model is developed to describe the mechanism and deformation of the wrinkle–crease transformation, and it shows good agreement with the FE prediction within an inevitable limitation of FEs.
我们研究了皱纹-褶皱转化过程中的变形,以揭示压缩下弹性体表面发生的皱纹和褶皱不稳定性之间的缺失环节。我们结合非线性扰动方法进行了平面应变有限元(FE)分析,为处于稳定状态的平面找到了两个分叉解。第一个解是褶皱演变的稳定变形路径,第二个解是之前未知的从起皱到褶皱的不稳定变形路径。这两条变形路径并不是独立的,它们在起皱的临界应变εC处相连。在 εC 处产生的变形是导致褶皱的前驱变形。虽然不稳定路径是由起皱不稳定性作为分岔开始的,但起皱不稳定性(即 εC)被解释为不稳定路径切换到稳定路径的奇点。建立了一个链式反应模型来描述起皱-起皱转变的机理和变形,在有限元分析不可避免的局限性范围内,该模型与有限元分析的预测结果显示出良好的一致性。
Phase-field simulation and coupled criterion link echelon cracks to internal length in antiplane shear
Gergely Molnár, Aurélien Doitrand, Véronique Lazarus
doi:10.1016/j.jmps.2024.105675
相场模拟和耦合准则将反平面剪切中梯队裂纹与内部长度联系起来
This paper provides a comprehensive numerical analysis of daughter crack localization in pure antiplane shear. Although antiplane shear fracture is important in various industrial applications, understanding the morphology of the resulting fragmentation remains challenging. The paper develops innovative phase-field models to induce the facets using a small spatial variation in the toughness field and examines the impact of numerical and material parameters on the newly formed daughter cracks’ shape and spacing. Through meticulous comparison to the coupled criterion, the paper reveals a compelling connection between the internal length-scale of damage regularization, Irwin’s length and the facet crack spacing. Furthermore, the effect of Poisson’s ratio on the crack form and spacing is investigated: the results reveal a significant influence and showcase comparable initiation distances between the numerical simulations and experimental measurements in pure antiplane loading.
本文对纯反平面剪切中子裂纹局部化问题进行了全面的数值分析。尽管反平面剪切裂缝在各种工业应用中很重要,但了解由此产生的碎片的形态仍然具有挑战性。本文开发了创新的相场模型,利用韧性场的小空间变化来诱导面,并研究了数值参数和材料参数对新形成的子裂纹形状和间距的影响。通过与耦合准则的细致对比,揭示了损伤正则化的内部长度尺度、欧文长度与面裂纹间距之间存在着令人信服的联系。此外,研究了泊松比对裂纹形式和间距的影响:结果表明,在纯反平面加载下,数值模拟和实验测量结果之间具有相当的起裂距离。
Bioinspired Soft-Hard Interfaces Fabricated by Multi-material Additive Manufacturing: A Fracture Mechanics Investigation using Essential Work of Fracture
Umut Altuntas, Demirkan Coker, Denizhan Yavas
doi:10.1016/j.mechmat.2024.105035
多材料增材制造仿生软硬界面:基于断裂基本功的断裂力学研究
This study employs the Essential Work of Fracture (EWF) concept to evaluate the interfacial fracture toughness of bioinspired interfaces between soft-hard polymer phases. The experimental framework utilizes a model material system with Polylactic Acid (PLA) as the hard phase and Thermoplastic Polyurethane (TPU) as the soft phase. Employing the Fused Filament Fabrication (FFF) technique, bioinspired sutural interfaces are created, characterized by interpenetrating soft and hard protrusions. The modulation of a critical parameter in the FFF process enables the variation of interpenetration length of protrusions at the interface, thereby achieving a spectrum of interfacial strength and toughness. The determination of essential work of fracture from double edge notch tension samples, with varied ligament sizes, allows for the specific EWF measurement. This specific EWF is found to align with the initiation value of plane strain interfacial fracture toughness obtained through the Double Cantilever Beam (DCB) test. Therefore, the proposed approach asserts the elimination of the need for complex interfacial fracture tests, such as DCB. A noteworthy discovery is the establishment of a correlation between specific plastic energy dissipation and protrusion length. This correlation suggests an increased plastic dissipation with longer protrusions within the investigated bioinspired interface. Due to this heightened plastic energy dissipation, the shape of the interfacial nominal stress-displacement curves demonstrates substantial dependence on interface morphology, shifting from a triangular shape to a trapezoidal shape as protrusion length increases. These findings offer valuable insights into the mechanics of bioinspired interfaces, presenting a more efficient and nuanced approach to characterizing their fracture properties.
本研究采用断裂基本工作(EWF)的概念来评估软硬聚合物相间仿生界面的断裂韧性。实验框架采用以聚乳酸(PLA)为硬相,热塑性聚氨酯(TPU)为软相的模型材料体系。采用熔融丝制造(FFF)技术,创造了仿生缝合线界面,其特点是软、硬突相互穿透。FFF过程中一个关键参数的调制可以改变界面上突起的穿透长度,从而获得界面强度和韧性的谱。从不同韧带大小的双边缘缺口张力样品中确定断裂的基本工作,允许特定的EWF测量。该特殊EWF与双悬臂梁(DCB)试验获得的平面应变界面断裂韧性起始值一致。因此,所提出的方法主张消除了对复杂界面破裂测试的需要,例如DCB。一个值得注意的发现是建立了比塑性能量耗散与突出长度之间的关系。这种相关性表明,在所研究的仿生界面内,随着突出物的延长,塑性耗散增加。由于这种增强的塑性能量耗散,界面名义应力-位移曲线的形状与界面形态有很大的关系,随着突出长度的增加,界面形状从三角形转变为梯形。这些发现为生物界面的力学提供了有价值的见解,提出了一种更有效、更细致的方法来表征其断裂特性。
On the strength-ductility modifications in pure copper after severe plastic deformation
Pouya Tajdary, Léo Morin, Chedly Braham, Omar Novelo Peralta, Gonzalo Gonzalez
doi:10.1016/j.mechmat.2024.105028
纯铜剧烈塑性变形后的强度-塑性变化
The aim of this work is to investigate experimentally and numerically the modifications of both strength and ductility after processing by severe plastic deformation, using several passes of repetitive corrugation and straightening on sheets made of pure copper. Experimental stress–strain curves are determined before and after processing in order to study the influence of the process on the mechanical properties. The modelling of the mechanisms responsible of the mechanical properties evolution is done through the development of an extended Gurson model including a dislocation-based modelling of hardening. The model developed is implemented into a finite element code and applied to the numerical prediction of the repetitive corrugation and straightening followed by a tensile test. The modifications of strength and ductility predicted numerically are qualitatively in good agreement with the experimental observations.
这项工作的目的是通过实验和数值研究在纯铜板上使用多次重复波纹和矫直的严重塑性变形处理后强度和延性的变化。为了研究工艺对力学性能的影响,测定了加工前后的实验应力-应变曲线。通过开发扩展的Gurson模型,包括基于位错的硬化模型,对负责力学性能演变的机制进行建模。将所建立的模型应用到有限元程序中,并应用于反复波纹和矫直后的拉伸试验的数值预测。数值预测的强度和延性变化与实验结果在定性上符合得很好。
Investigation of forming process and deformation mechanisms of 3D warp interlock fabric
Xiaoyu Hong, Zhongxiang Pan, Jiajia Yu, Zhiping Ying, Yongqiang Liu, Zhenyu Wu
doi:10.1016/j.tws.2024.111964
三维经纱互锁织物成形过程及变形机理研究
This article introduces a modeling method aimed at predicting the internal geometric structure of 3D warp interlock fabric. Inspired by the digital element method, the method employs truss elements to model the yarns as fiber bundles, and considers their material properties. This technique allows for predicting the microstructure of 3D woven fabric based on simple input characteristics. By varying the elastic modulus of virtual fibers, the friction coefficient between fibers, and the tension load at the ends of yarns, and designing compression molding molds to compress the fabric into shape, the virtual fiber fabric predicted the influence of variables on the fabric. The study found that the structure of the samples obtained through CT scanning is generally consistent with the structure of the virtual fiber fabric. The elastic modulus has a relatively minor impact on the fabric structure, whereas the friction coefficient and tension load significantly affect the cross-sectional shape of the yarns. During compression molding, deformation within the mold leads to interlayer fabric slippage and changes in the cross-sectional shape of the fabric. This suggests the feasibility and applicability of virtual simulation testing methods for analyzing the behavior of various types of 3D woven fabrics.
本文介绍了一种预测三维经纱互锁织物内部几何结构的建模方法。该方法受数字单元法的启发,采用桁架单元将纱线作为纤维束进行建模,并考虑其材料特性。该技术可以基于简单的输入特性预测三维机织织物的微观结构。通过改变虚拟纤维的弹性模量、纤维间的摩擦系数、纱线两端的张力载荷,设计压缩成型模具,对织物进行压缩成型,预测各种变量对织物的影响。研究发现,通过CT扫描获得的样品结构与虚拟纤维织物的结构基本一致。弹性模量对织物结构的影响相对较小,而摩擦系数和张力载荷对纱线的横截面形状影响较大。在压缩成型过程中,模具内部的变形导致织物层间滑动,织物的横截面形状发生变化。这说明了虚拟仿真测试方法在分析各类三维机织物性能方面的可行性和适用性。
Effects of structural parameters on radial crashworthiness of 3D braided hybrid tubes with Janus structure
Qiujin Gu, Zhenzhen Quan, Jianyong Yu
doi:10.1016/j.tws.2024.111991
结构参数对双面结构三维编织复合管径向耐撞性的影响
Hybrid fiber reinforced plastic (HFRP) composites have been widely used in various fields, but delamination is a fatal damage mode in laminated hybrid tubes. In the current paper, carbon fibers/Kevlar fibers hybrid tubes with Janus structure were fabricated by three-dimensional (3D) tubular braiding technique. The radial crushing performances of 3D braided Janus hybrid tubes were analyzed while hybrid layer ratio and yarn type were both considered. With the increase of hybrid layer ratio from 1:3 to 2:2 to 3:1, the specific energy absorption (SEA) increased 149% and 21.39% for specimens with carbon fibers placed on the skin region, and that decreased 12.46% and 10.66% for samples with Kevlar fibers arranged on the skin region. Furthermore, samples with Kevlar fibers arranged on the skin region presented excellent radial crashworthiness. The current work could be helpful for the design, fabrication and application of HFRP tubes.
混杂纤维增强塑料(HFRP)复合材料已广泛应用于各个领域,但分层是复合材料层合管的一种致命损伤模式。本文采用三维管状编织技术制备了具有Janus结构的碳纤维/凯夫拉纤维杂化管。在考虑混杂层比和纱线类型的情况下,分析了三维编织杂化管的径向破碎性能。杂化层数比从1:3增加到2:2再增加到3:1,碳纤维层数比提高149%和21.39%,凯夫拉纤维层数比降低12.46%和10.66%。此外,在皮肤区域排列凯夫拉纤维的样品具有优异的径向耐撞性。本文的研究对HFRP管的设计、制造和应用具有一定的指导意义。
Robust topology optimization for multi-material structures considering material uncertainties
Yongfeng Zheng, Zihao Chen, Baoshou Liu, Ping Li, Jiale Huang, Zhipeng Chen, Jianhua Xiang
doi:10.1016/j.tws.2024.111990
考虑材料不确定性的多材料结构鲁棒拓扑优化
Multi-material structures have attracted more and more attention from scholars and engineers, because they usually have good composite performance. Uncertainty factors are ubiquitous in practice, especially for material uncertainties. Multi-material structures contain many materials with different properties, material uncertainties will affect the allocation of material usage, thereby affecting structural performance. Therefore, it is crucial to consider material uncertainties in the design of multi-material structures. This paper detailedly explores the impacts of elastic modulus uncertainty and Poisson's ratio uncertainty on the design of multi-material structures. The topology optimization is to minimize the compliance subjected to a mass constraint, where multiple materials can be freely allocated during the optimization. Floating projection topology optimization is adopted to search for the structural topologies, and robust sensitivity information is derived. For the quantification of material uncertainties, this paper introduces a non-intrusive polynomial chaos expansion (PCE) method to implicitly quantify them, the computational efficiency and accuracy in PCE is compared with the classical Monte Carlo method. Finally, topology optimization examples are provided to demonstrate the effects of elastic modulus uncertainty, Poisson's ratio uncertainty and hybrid uncertainty on the design of multi-material structures.
多材料结构由于具有良好的复合性能,越来越受到学者和工程师的关注。不确定性因素在实践中普遍存在,特别是在材料不确定性方面。多材料结构包含许多具有不同性能的材料,材料的不确定性会影响材料使用的分配,从而影响结构的性能。因此,在多材料结构设计中,考虑材料的不确定性是至关重要的。详细探讨了弹性模量不确定性和泊松比不确定性对多材料结构设计的影响。拓扑优化是为了使受质量约束的顺应性最小化,在优化过程中多种材料可以自由分配。采用浮动投影拓扑优化对结构拓扑进行搜索,得到鲁棒灵敏度信息。针对材料不确定性的量化问题,提出了一种非侵入式多项式混沌展开(PCE)方法对材料不确定性进行隐式量化,并将其计算效率和精度与经典蒙特卡罗方法进行了比较。最后,通过拓扑优化算例验证了弹性模量不确定性、泊松比不确定性和混合不确定性对多材料结构设计的影响。
Stiffness enhancement methods for thin-walled aircraft structures: A review
Rui Ren, Xiangyu Ma, Honghao Yue, Fei Yang, Yifan Lu
doi:10.1016/j.tws.2024.111995
薄壁飞机结构刚度增强方法综述
The rapid development of next-generation spacecraft technology has placed increasingly stringent requirements on the lightweight level of structural components. As a result, many aerospace structures are presented in the form of thin-walled structures. Under complex and extreme thermal service environments, thin-walled structures of aircraft are susceptible to thermal buckling failure and vibration caused by reduced stiffness. Therefore, how to achieve stiffness enhancement in thin-walled structures has become a challenging issue of widespread concern in the field of advanced materials and structural manufacturing. The main contribution of this work is to provide a comprehensive review of the stiffness enhancement methods for thin-walled aircraft components in recent years. The passive stiffness enhancement methods based on laminated plates and stiffeners of thin-walled structures are discussed first; then the active stiffness enhancement methods based on diverse smart materials are reviewed. The key technical challenges that need to be addressed in achieving passive and active stiffness enhancement in thin-walled structures are systematically analyzed. Finally, the development prospects and applications of smart materials for stiffness enhancement in thin-walled aircraft structures are discussed. This paper aims to provide a reference for future research and development in the field of aerospace equipment and contribute to related studies in the field.
新一代航天器技术的快速发展对结构部件的轻量化水平提出了越来越严格的要求。因此,许多航空航天结构以薄壁结构的形式呈现。在复杂的极端热环境下,飞机薄壁结构容易因刚度降低而发生热屈曲破坏和振动。因此,如何实现薄壁结构的刚度增强已成为先进材料和结构制造领域广泛关注的一个具有挑战性的问题。本文的主要贡献是对近年来薄壁飞机部件的刚度增强方法进行了全面的综述。首先讨论了薄壁结构基于层合板和加劲板的被动增强刚度方法;然后对基于各种智能材料的主动刚度增强方法进行了综述。系统分析了薄壁结构在实现被动和主动刚度增强过程中需要解决的关键技术挑战。最后,讨论了智能材料在薄壁飞机结构中增强刚度的发展前景和应用。本文旨在为未来航空航天装备领域的研究与发展提供参考,为相关领域的研究做出贡献。