【新文速递】2024年8月23日固体力学SCI期刊最新文章

 

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 1 篇，International Journal of Plasticity 2 篇，Thin-Walled Structures 5 篇

International Journal of Solids and Structures

Dynamic multifield continualization of multilayered lattice-like metamaterials

Francesca Fantoni, Andrea Bacigalupo, Luigi Gambarotta

doi:10.1016/j.ijsolstr.2024.113015

多层类晶格超材料的动态多场连续化

This work focuses on dynamic continualization of multifield multilayered metamaterials in order to obtain energetically-consistent models able to provide an accurate description of the dispersive behavior of the corresponding discrete system. Continuum models, characterized by constitutive and inertial non-localities, have been identified through a recently proposed enhanced continualization scheme. They are identified by governing equations both of the integro-differential and higher-order gradient-type, whose regularization kernel or pseudo-differential functions accounting for shift operators are formally expanded in Taylor series. The adopted regularization kernel exhibits polar singularities at the edge of the first Brillouin zone, thus assuring the convergence of the frequency spectrum to the one of the Lagrangian system in the entire wave vector domain. The validity of the proposed approach is assessed through the investigation of multilayered discrete lattices with an antitetrachiral topology, where local resonators act as rigid links among the layers. The convergence of dispersion curves of the continuum model to the ones of the Lagrangian model is proved in the whole first Brillouin zone as the adopted continualization order increases, both considering the propagation and the spatial attenuation of Bloch waves inside the metamaterial. A low frequency continualization is also provided, leading to the identification of a first-order medium.

本研究的重点是多场多层超材料的动态连续化，以获得能够准确描述相应离散系统色散行为的能量一致模型。通过最近提出的一种增强连续化方案，确定了以本构和惯性非局部为特征的连续模型。它们由积分微分型和高阶梯度型的控制方程来标识，其正则化核或伪微分函数对移位算子进行了泰勒级数形式展开。所采用的正则化核在第一布里渊区边缘表现出极奇点，从而保证了整个波矢量域的频谱收敛到拉格朗日系统的频谱。通过研究具有反四面拓扑的多层离散晶格来评估所提出方法的有效性，其中局部谐振器充当层之间的刚性链接。在考虑布洛赫波在超材料内部的传播和空间衰减的情况下，随着连续化阶数的增加，在整个第一布里渊区证明了连续统模型的色散曲线收敛于拉格朗日模型的色散曲线。还提供了低频连续化，导致一阶介质的识别。

Geometric symmetry and mechanical behavior of Topologically Interlocked Material systems from skewed building blocks

Dong Young Kim, Thomas Siegmund

doi:10.1016/j.ijsolstr.2024.113033

歪斜砌块构成的拓扑互锁材料系统的几何对称性和力学行为

Architectured materials are engineered materials with specific geometries and arrangements to exhibit desired mechanical properties. One class of architectured material is the Topologically interlocked material (TIM) system. In TIM systems, a plurality of convex particles is assembled under specific geometric constraints such that a load-carrying structure is obtained without the need for an adhesive bond between building blocks. Past investigations have considered TIM systems with building blocks and assemblies with a high degree of symmetry. Here the geometric constraints commonly imposed on the geometry of the system are relaxed. Two new types of skewed building blocks are introduced: one with only a rotational symmetry and no mirror symmetry, and one without rotational or mirror symmetry. These blocks are used to build even and odd-numbered assemblies and to create TIM systems with both mirror and rotational symmetry, rotational symmetry only, and no symmetry. A vector field representing the material architecture is introduced and demonstrated to connect architecture and mechanical behavior. It is demonstrated that load transfer patterns in the TIM system closely match the geometric symmetry. This allows for the demonstration of achiral and chiral mechanical behavior as represented by the presence of reaction moments for the centrally loaded square TIM assembly. The chirality of the building blocks manifests itself in the mechanical behavior of the TIM system only once the deflection of the system opens the contacts between building blocks such that building blocks accommodate deformation. Chiral building blocks diffuse the load from the central load path dominant in the TIM systems built from achiral blocks. This construction concept allows for simultaneous improvements in mechanical properties (strength and stiffness) solely from geometry.

建筑材料是具有特定几何形状和排列的工程材料，以表现出所需的机械性能。一类建筑材料是拓扑互锁材料(TIM)系统。在TIM系统中，在特定的几何约束下组装多个凸颗粒，使得在不需要在构建块之间进行粘合剂粘合的情况下获得承载结构。过去的研究考虑了具有高度对称性的构建块和组件的TIM系统。在这里，通常施加在系统几何上的几何约束被放宽了。介绍了两种新的歪斜构件:一种是只有旋转对称而没有镜像对称，一种是没有旋转或镜像对称。这些块用于构建偶数和奇数的组件，并创建镜像对称和旋转对称、仅旋转对称和不对称的TIM系统。介绍并演示了代表材料结构的矢量场，以连接结构和力学行为。结果表明，TIM系统的载荷传递模式与几何对称性非常吻合。这允许展示非手性和手性机械行为，由中心加载的方形TIM组件的反应力矩表示。只有当系统的偏转打开了构建块之间的接触，使得构建块可以容纳变形时，构建块的手性才会在TIM系统的机械行为中表现出来。在由非手性构件构建的TIM系统中，手性构件分散了来自中心负载路径的负载。这种结构概念允许机械性能(强度和刚度)的同时改进，仅从几何形状。

Journal of the Mechanics and Physics of Solids

Effects of adhesive and frictional contacts on the nanoindentation of two-dimensional material drumheads

Yifan Rao, Nanshu Lu

doi:10.1016/j.jmps.2024.105828

粘接和摩擦接触对二维材料鼓面纳米压痕的影响

Nanoindentation of suspended circular thin films, dubbed drumhead nanoindentation, is a widely adopted technique for characterizing the mechanical properties of micro- or nano-membranes, including atomically thin two-dimensional (2D) materials. This method involves suspending an ultrathin specimen over a circular microhole and applying a precise indenting force at the center using an atomic force microscope (AFM) probe. Classical solutions assuming a point load and a fixed edge, which are referred to as Schwerin-type solutions, are commonly used to estimate Young’s modulus of the membrane material out of load–deflection measurements. However, given the widespread experimental evidence for adhesive and frictional contacts between the probe tip and the membrane, as well as sliding between the membrane and its supporting substrate, quantitative investigations of the effects of these interactions are required. In this paper, we formulate a boundary value problem to rigorously model such effects, ensuring relevance to experimental operations. Our numerical analyses reveal that the adhesive effect at the tip-membrane interface diminishes as the indentation depth increases or the tip size decreases. Furthermore, frictional interactions at this interface shift the maximum membrane stress from the center to the tip-membrane contact line with increasing indentation depth and interfacial shear stress. At large indentation depths, the size of the indenter tip and the sliding of the membrane-substrate are found to have a large effect on the indentation load–deflection relationship. Thus, we propose a new approximate formula for this relationship assuming a non-adhesive and frictionless spherical tip of a finite radius and a slippery contact with the supporting substrate. This formula is more accurate than the widely used Schwerin-type solution. It can be used to simultaneously extract the in-plane stiffness of the membrane and the shear strength at the membrane-substrate interface.

悬浮圆形薄膜的纳米压痕，被称为鼓面纳米压痕，是一种广泛采用的表征微或纳米膜(包括原子薄的二维材料)机械性能的技术。该方法包括将超薄样品悬浮在圆形微孔上，并使用原子力显微镜(AFM)探针在中心施加精确的压痕力。假设点载荷和固定边的经典解被称为schwerin型解，通常用于估计膜材料在载荷-挠度测量中的杨氏模量。然而，鉴于探针尖端和膜之间的粘着和摩擦接触以及膜与其支撑基板之间的滑动的广泛实验证据，需要对这些相互作用的影响进行定量研究。在本文中，我们制定了一个边值问题来严格模拟这种效应，以确保与实验操作的相关性。数值分析表明，随着压痕深度的增加或压痕尺寸的减小，粘接效应减弱。此外，随着压痕深度和界面剪应力的增加，该界面上的摩擦相互作用使最大膜应力从中心转移到膜端接触线。在较大的压痕深度下，压痕尖端的尺寸和薄膜-衬底的滑动对压痕载荷-挠度关系有很大的影响。因此，我们提出了一个新的近似公式，假设一个有限半径的无粘性和无摩擦的球形尖端和与支撑基板的光滑接触。该公式比广泛使用的schwerin型溶液更精确。它可以同时提取膜的面内刚度和膜-基底界面处的抗剪强度。

Mechanics of Materials

Effects of intergranular hydride precipitation on the mechanical behavior of bicrystalline zirconium: a Molecular dynamics-based study

Sanjay Patil, Avinash Parashar

doi:10.1016/j.mechmat.2024.105124

晶间氢化物沉淀对双晶锆力学行为的影响:基于分子动力学的研究

This article investigated the impact of intergranular hydride precipitation on the mechanical behavior of zirconium (Zr) bi-crystals using molecular dynamics (MD)-based simulations. Uniaxial tensile tests were conducted to explore the effects of hydride precipitation on symmetric and asymmetrical tilt grain boundaries (GBs) of Zr with [0  10] as the tilt axis. The stress-strain curves and deformation governing mechanism of bi-crystalline Zr were analyzed using the MD-based simulations in conjunction with the COMB force field. Misfit stress and tensile stress degradation induced by hydride precipitation were evaluated to understand their correlation with GB misorientation angles. Hydride precipitation induced the residual stresses in the vicinity of GB plane and mitigates the overall mechanical properties. It was predicted from the simulations that GBs with low misfit stress develop a lower mismatch between the lattice of Zr and hydride precipitate. Consequently, the effect of hydride on the tensile strength gets nullify. In contrast, the effects of hydrides are more pronounced on the tensile strength of Zr containing low-energy GBs in conjunction with high-misfit stress. The study further reveals that intergranular hydride precipitation causes the hydride embrittlement effect in Zr bicrystals, which intensifies with large size hydride precipitate. These findings contribute to an atomistic-level understanding of intergranular hydride-induced embrittlement and its correlation with Zr grain boundary orientation.

本文采用基于分子动力学(MD)的模拟方法研究了晶间氢化物沉淀对锆(Zr)双晶力学行为的影响。通过单轴拉伸试验，探讨氢化物析出对以[0 10]为倾斜轴的Zr对称和不对称倾斜晶界(GBs)的影响。结合COMB力场，利用md模拟分析了双晶Zr的应力-应变曲线和变形控制机理。对氢化物沉淀引起的失配应力和拉应力退化进行了评价，以了解它们与GB错取向角的关系。氢化物的析出引起了GB平面附近的残余应力，降低了整体力学性能。模拟结果表明，低错配应力的GBs在Zr晶格与氢化物析出物之间的错配程度较低。从而消除了氢化物对拉伸强度的影响。相反，氢化物对含有低能GBs的Zr的抗拉强度的影响更为明显，并伴有高错配应力。研究进一步表明，晶间氢化物析出引起Zr双晶的氢化物脆化效应，且随着大尺寸氢化物析出而加剧。这些发现有助于在原子水平上理解晶间氢化物引起的脆化及其与Zr晶界取向的关系。

International Journal of Plasticity

Interpretation of the Stress Dip Test as a Means of Characterizing Backstress: Experiments and Backstress-aided Crystal Plasticity Modeling of Polycrystalline Tantalum

Sajjad Izadpanah Najmabad, David Fullwood, Tristan Russell, Marko Knezevic, Michael Miles

doi:10.1016/j.ijplas.2024.104089

应力倾斜试验作为表征背应力的手段的解释:多晶钽的实验和背应力辅助晶体塑性建模

Backstresses, associated with certain dislocation arrangements and their inter-dislocation long-range stresses, are known to contribute significantly to deformation response of metals, including kinematic hardening, the Bauschinger effect (BE) and the Hall-Petch effect. Various methods have been employed to quantify these backstresses at the macro-scale. One of these approaches, which has received relatively little attention, is the stress dip test. The strain rate observed during a load dip and hold, after previous plastic deformation, can be positive or negative, depending upon the level at which the load is held, and the relative magnitudes of competing friction and backstresses. The most direct interpretation of previously reported tests indicates a surprisingly high level of backstress in common materials, and which is generally also higher than the value extracted from an unload-reload test. In this paper, stress dip tests are performed on pure polycrystalline tantalum, along with unload-reload tests. A plateau is seen in the strain rate observed during the stress dip test, which has not been previously reported. If the backstress is interpreted to correspond with the stress level associated with the middle point of the plateau, in line with the friction/backstress model of the unload-reload test, the resulting backstress obtained from both tests are very similar. A novel crystal plasticity model, incorporating backstress, reversible dislocations and non-Schmid effects, is used to help justify this new approach. The model predicts the observed plateau in strain rate, and provides a slip-level interpretation of the macroscopically observed backstress. The slip-level backstress (when considered as a fraction of the stress prior to the dip) is reasonably similar to the values interpreted from the dip test experiment. The ∼23% lower value in the simulation may be due to the lack of certain aspects of the actual physics in the model.

背应力与某些位错排列及其位错间的远程应力有关，对金属的变形响应有重要影响，包括运动硬化、鲍辛格效应(BE)和霍尔-佩奇效应。在宏观尺度上，已经采用了各种方法来量化这些背应力。其中一种受到相对较少关注的方法是压力下降测试。在先前的塑性变形之后，在负载下降和保持期间观察到的应变率可以是正的或负的，这取决于保持负载的水平，以及竞争摩擦和背应力的相对大小。对先前报告的试验的最直接解释表明，普通材料的背应力水平高得惊人，而且通常也高于从卸载-重新加载试验中提取的值。本文对纯多晶钽进行了应力倾斜试验，并进行了卸载-重新加载试验。在应力跌落试验中观察到的应变速率出现平台，这在以前没有报道过。如果将背应力解释为与高原中点相关的应力水平相对应，并与卸载-重新加载试验的摩擦/背应力模型相一致，则从两个试验中获得的最终背应力非常相似。一种新的晶体塑性模型，结合了背应力、可逆位错和非施密德效应，有助于证明这种新方法的合理性。该模型预测了观测到的应变速率平台，并提供了宏观观测到的背应力的滑移水平解释。滑移水平的反应力(当考虑为倾斜前应力的一部分时)与倾斜测试实验解释的值相当相似。模拟中较低的~ 23%的值可能是由于模型中缺乏实际物理的某些方面。

Nanostructured amorphous Al2O3-ZrO2 (La2O3) ceramics with plastic deformation via interface inducing hierarchical shear bands

Jianglin Wang, Shuhuai Wang, Yongkang Yang, Shuai Wang, Jie Li, Ziqi Jia, Binghui Ge, Xinghua Su, Anran Guo, Jiachen Liu, Shuxin Niu, Xiqing Xu

doi:10.1016/j.ijplas.2024.104103

纳米结构非晶Al2O3-ZrO2 (La2O3)陶瓷通过界面诱导分层剪切带进行塑性变形

Ionic-bonded ceramics are featured by their thermal stability, corrosion resistance, hardness and strength, but their applications are limited by the inherent brittleness. Ceramics are composed of strong chemical bonding and intricate crystal structures, making plastic deformation by dislocation slip highly challenging. A nanostructured amorphous Al2O3-ZrO2 ceramic comprising nanoscale amorphous particles and amorphous interfaces between particles was achieved in practice, where the amorphous interface is in scale of approximately 2.34 nm and amorphous particles is in width of approximately 6.75 nm. Based on nano-indentation tests, the shear transformation zone (STZ) volumes of nanostructured amorphous ceramics hot-pressed under various conditions are calculated, suggesting attenuation of free volume with the increase in pressure and temperature. The medium-temperature compression test of the samples exhibits a permanent plastic deformation of 14.6%, with the presence of hierarchical shear bands in the deformed samples. The main shear bands (MSBs) in width of 0.84-9.15 μm are generated by the stress concentration in crystal-amorphous interface, and the small shear bands (SSBs) of 31-428 nm are related to abundant free volumes in the interface between amorphous particles.

离子键合陶瓷具有热稳定性、耐腐蚀性、硬度和强度等特点，但其固有的脆性限制了其应用。陶瓷是由强大的化学键和复杂的晶体结构组成的，使得位错滑移的塑性变形非常具有挑战性。在实践中获得了由纳米级非晶颗粒和颗粒间非晶界面组成的纳米结构非晶Al2O3-ZrO2陶瓷，其中非晶界面尺寸约为2.34 nm，非晶颗粒宽度约为6.75 nm。在纳米压痕实验的基础上，计算了不同条件下热压下纳米结构非晶陶瓷的剪切转变区(STZ)体积，表明自由体积随压力和温度的升高而衰减。中温压缩试验中，试样的永久塑性变形率为14.6%，变形试样中存在分层剪切带。应力集中产生的剪切带宽度为0.84 ~ 9.15 μm，较小的剪切带宽度为31 ~ 428 nm，与非晶态颗粒界面中丰富的自由体积有关。

Thin-Walled Structures

Scratch-induced micro-fracture behaviour and translational failure of glass: An experimental and numerical study

Zhufeng Pan, Jian Yang, Xing-Er Wang, Dongdong Xie, Chenjun Zhao

doi:10.1016/j.tws.2024.112341

玻璃划痕诱导的微断裂行为与平移破坏:实验与数值研究

The structural safety of aged glass members shows significant sensitivity to surface scratches. The distribution and geometrical features of scratch impacts the glass fracturing. In this study, the fracture behaviour of scratched thin glass pane was investigated by the ordinary state-based peridynamic (OSB-PD) theory. Coaxial double ring test was first conducted to identify the mechanical and fracture behaviour of scratched glass plates that serve as the benchmark. The applicability of simplifying and reconstructing the actual scratches in numerical models was then examined. The refined three-dimensional fracture process from micro-crack coalescence to macro-propagation of featured cracks can be well described by the developed PD model. The propagation of in-plane radial cracks was found prior to median cracks along the thickness for scratched glass. Crack branch was observed due to shallow scratch depth and the primary crack branching point lies near the edge of the scratch. The transition from scratch-induced failure to strength-induced failure due to particular scratch spatial location was also tackled, which benefits the accurate performance assessment of scratched glass.

老化玻璃构件的结构安全性对表面划痕表现出显著的敏感性。划痕的分布和几何特征影响着玻璃的破裂。本文采用基于普通状态动力学(OSB-PD)理论研究了划痕薄板的断裂行为。首先进行了同轴双环试验，以确定作为基准的划痕玻璃板的力学和断裂行为。并对简化和重构实际划痕在数值模型中的适用性进行了验证。所建立的PD模型可以很好地描述从微裂纹合并到特征裂纹宏观扩展的精细三维断裂过程。沿厚度方向，划痕玻璃的面内径向裂纹先于中间裂纹扩展。由于划痕深度较浅，可见裂纹分支，主裂纹分支点位于划痕边缘附近。此外，还解决了特定划痕空间位置导致的从划痕破坏到强度破坏的过渡问题，这有利于对划痕玻璃进行准确的性能评估。

Dynamic response and failure characteristics of the fluid-filled concave multicell structure under combined blast and fragments loading

Zhujie Zhao, Dian Li, Hailiang Hou, Xiaowei Wu, Yongqing Li, Mengmeng Wu

doi:10.1016/j.tws.2024.112357

爆破破片复合载荷下充液凹多室结构的动力响应及破坏特性

The deformation and damage characteristics of the fluid-filled concave multicell structure under the charge explosion with preset fragments are investigated to assess its performance against combined blast and fragments loading. The failure characteristics of the structure, the propagation process of loads, and the dynamic response characteristics of the structure are analyzed using experimental research and SPH-ALE numerical simulation. The results indicate that the deformation of the structure, caused by the explosion of a charge with preset fragments, is 400% greater than the deformation caused by the explosion alone. The propagation of the load is influenced by the panels of the structure and the irregular regions where fluid is filled. The deformation and failure of the fluid-filled concave multicell structure occur in two stages. The failure mode of this structure can be seen as a combination of the failure modes of individual single-cell structures, based on the method of fluid filling. The strength distribution of the structure plays a crucial role in determining the failure of the fluid-filled concave multicell structure.

研究了充液凹型多室结构在装药爆破下的变形与损伤特性，评价了其抗爆破与破片复合载荷的性能。采用试验研究和SPH-ALE数值模拟相结合的方法，分析了结构的破坏特征、荷载的传播过程以及结构的动力响应特性。结果表明，带预定破片的装药爆炸引起的结构变形比单独爆炸引起的变形大400%。载荷的传播受结构面板和填充流体的不规则区域的影响。充液凹多孔结构的变形和破坏分两个阶段进行。这种结构的破坏模式可以看作是基于流体填充方法的单个单细胞结构破坏模式的组合。结构的强度分布对充液凹多室结构的破坏起着至关重要的作用。

Analysis of Influential Factors on Additional Shear Force Induced by Shear Deformation in Girder Bridges with Corrugated Steel Webs

Jilong Chai, Man Zhou, Yufeng Zhang

doi:10.1016/j.tws.2024.112358

波纹钢腹板梁桥剪切变形产生附加剪力的影响因素分析

Girder bridges with corrugated steel webs (CSWs) exhibit critical shear regions proximate to supports, where the CSWs are subjected to peak shear forces and bending moments potentially inducing shear buckling. This study explores the shear behavior within critical regions experiencing hogging bending moments, where the accordion effect of CSWs dramatically exacerbates shear deformation. However, due to the substantially reduced shear stiffness of CSWs relative to concrete slabs and crossbeams, the shear deformation of CSWs is constrained, causing additional shear forces to form within them. The traditional basic shear method proves inadequate in predicting shear stress within CSWs for it omits these additional shear forces. The study introduces an enhanced formula to precisely assess shear stresses within CSWs, particularly in hogging moment regions of girders, considering the additional shear force induced by CSWs' shear deformation. A strong correlation between the additional shear forces and the geometric characteristics of CSWs has been identified through theoretical analysis. Accordingly, the study systematically investigates the impact of various parameters on the additional shear force through finite element parametric analysis. Comparative analysis demonstrates that the CSWs’ thickness, the height-to-span ratio, and the boundary constraint conditions of girders significantly impact additional shear forces, thereby affecting the shear transfer efficiency within the cross-section of the girder.

波纹钢腹板(CSWs)的梁桥在支座附近表现出临界剪切区域，在那里，波纹钢腹板受到峰值剪切力和弯矩的影响，可能导致剪切屈曲。本研究探讨了临界弯矩区域内的剪切行为，其中csw的手风琴效应显著加剧了剪切变形。然而，由于csw相对于混凝土板和横梁的剪切刚度大大降低，csw的剪切变形受到约束，导致其内部形成额外的剪切力。传统的基本剪切法由于忽略了这些附加剪切力，在预测csw内部剪切应力方面存在不足。该研究引入了一个改进的公式来精确评估csw内的剪切应力，特别是在梁的弯矩区域，考虑csw剪切变形引起的附加剪切力。通过理论分析，确定了附加剪切力与csw几何特性之间存在很强的相关性。因此，本研究通过有限元参数分析，系统考察了各参数对附加剪力的影响。对比分析表明，csw的厚度、高跨比和梁的边界约束条件对附加剪力的影响较大，从而影响梁截面内的剪切传递效率。

Local buckling behaviour of Q690 high strength steel press-braked elliptical hollow section stub columns: Testing, numerical modelling, and design

Jun-Zhi Liu, Xiaowei Ma, Kangye Gao, Junbo Chen, Shuai Li, Jiachen Guo

doi:10.1016/j.tws.2024.112359

Q690高强度钢压制动椭圆空心截面短柱的局部屈曲行为:试验、数值模拟和设计

This paper presents comprehensive investigations on the local bucking behaviour of Q690 high strength steel (HSS) press-braked elliptical hollow section (EHS) stub columns subject to concentric compression experimentally. In comparison with conventional hot-finished EHS or cold-rolled EHS, the press-braked EHS provides high precision, great construction productivity and the fabricated geometries are not limited to production assembly instrumentation. HSS press-braked EHS fabricated through press-braking process was expected to exhibit distinct behaviour compared with their counterparts constructed from the conventional fabrication routes. Well-understanding of their performance at the levels of material, and cross-section level is essential. Material properties were obtained through tensile coupon tests. Residual stresses in both membrane and bending types were measured and recorded and their impact on structural performance was also assessed. Initial local geometric imperfection measurements were conducted for all the specimens. In conjunction with experimental studies, the finite element (FE) models of Q690 HSS press-braked EHS stub columns were developed. The accuracy of the FE model for HSS press-braked EHS stub column was asserted by comparing the numerical predictions with the tested results. An extensive parametric study was conducted to generate structural performance data with a wider range of cross-section slenderness to complement the test data bank. The cross-section classification for conventional CHS codified in existing standards and the proposed slenderness limits by various researchers were evaluated. The existing slenderness limits cannot be extended to HSS press-braked EHS investigated in this study, a new slenderness limit is proposed. Moreover, the advanced design approaches of Direct Strength Method (DSM) and Continuous Strength Method (CSM) were assessed for their applicability to the cross-section resistance predictions of the examined EHS stub columns.

本文对Q690高强度钢(HSS)压制动椭圆空心截面(EHS)短柱在同心压缩作用下的局部屈曲行为进行了实验研究。与传统的热加工EHS或冷轧EHS相比，压制动EHS具有高精度，高施工生产率和制造几何形状不限于生产装配仪表。通过压制动工艺制备的HSS压制动EHS与传统制造工艺制备的HSS压制动EHS相比，有望表现出不同的行为。在材料水平和横截面水平上充分了解它们的性能是必不可少的。通过拉伸试验获得了材料的性能。测量和记录了薄膜和弯曲两种类型的残余应力，并评估了它们对结构性能的影响。对所有试件进行了初始局部几何缺陷测量。结合试验研究，建立了Q690高强钢压制动EHS短柱的有限元模型。通过数值预测与试验结果的比较，验证了高速钢压制动EHS短柱有限元模型的准确性。进行了广泛的参数研究，以产生具有更大范围的截面长细比的结构性能数据，以补充测试数据库。对现有标准中对传统CHS的截面分类和不同研究者提出的长细限值进行了评价。现有的长细限值不能扩展到本研究研究的HSS压制动EHS，因此提出了新的长细限值。并对直接强度法(DSM)和连续强度法(CSM)这两种先进的设计方法在EHS短柱截面抗力预测中的适用性进行了评价。

A compact quasi-zero stiffness metamaterial for energy absorption and impact protection

Meng Jia, Ning Dai, Tingwei Wang, Qianfeng Cao, Lei Yan, Hongqing Dai

doi:10.1016/j.tws.2024.112360

一种紧凑的准零刚度超材料，用于能量吸收和冲击防护

A compact mechanical metamaterial for impact protection is proposed in this study. During compression, the unit cell of the metamaterial exhibits quasi-zero stiffness (QZS) and quasi-zero Poisson’s ratio (QZPR) characteristics, along with large densification strain, making it suitable for protection against low-speed impacts. Firstly, the parametric geometric model of the metamaterial is established, with sinusoidal thin-walled structures serving as the primary load-bearing units. The grid structures are employed to connect the thin-walled structures into a unified system. Secondly, to shorten the design cycle, numerical methods for the mechanical properties of the buffer structure are developed. The motion equation of the thin-walled structure are expressed in terms of arc length coordinates and solved using the Runge–Kutta method and the shooting method. The grid structure deformation and the effect of material plastic reinforcement on the structural mechanical response are analyzed, and the energy absorption (EA) of the buffer structure is calculated. Both simulation and experimental results demonstrate the high accuracy of the proposed calculation method. Lastly, drop hammer experiments are conducted to evaluate the impact mitigation performance of the designed buffer structure. The results indicate that the structure exhibits excellent impact mitigation capabilities, highlighting its potential for practical applications.

提出了一种用于冲击防护的紧凑型机械超材料。在压缩过程中，超材料的单元胞表现出准零刚度(QZS)和准零泊松比(QZPR)特性，以及较大的致密应变，使其适合低速冲击防护。首先，建立了以正弦薄壁结构为主要承载单元的超材料参数化几何模型;采用网格结构将薄壁结构连接成一个统一的体系。其次，为了缩短设计周期，提出了缓冲结构力学性能的数值计算方法。用弧长坐标表示薄壁结构的运动方程，用龙格-库塔法和射击法求解。分析了网格结构变形和材料塑性加固对结构力学响应的影响，计算了缓冲结构的能量吸收(EA)。仿真和实验结果都证明了所提出的计算方法具有较高的精度。最后进行了跌落锤试验，对所设计的缓冲结构进行了冲击缓冲性能评价。结果表明，该结构具有良好的抗冲击能力，具有实际应用潜力。