【新文速递】2024年1月16日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 4 篇，Journal of the Mechanics and Physics of Solids 2 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 2 篇，Thin-Walled Structures 4 篇

International Journal of Solids and Structures

Concurrent topology optimization of multiscale piezoelectric actuators

Cheng Liu, Zhelong He, Chaofeng Lü, Guannan Wang

doi:10.1016/j.ijsolstr.2024.112664

多尺度压电致动器并行拓扑优化

As an important component of smart structural devices, piezoelectric composites have strong macroscopic electromechanical coupling properties which often depend on their microstructural geometry and material parameters. Therefore, optimizing the microstructural design is crucial for achieving the desired macroscale effective properties. To this end, this paper conducts a concurrent multiscale topology optimization (TO) to optimize the material distribution of piezoelectric actuators, aiming to maximize the electrical and mechanical energy transmission to meet specific engineering requirements. Firstly, an energy method is used to homogenize the microstructures and obtain the effective parameters of the piezoelectric material. Then, the piezoelectric material with penalization and polarization (PEMAP-P) approach in conjunction with the adjoint method is employed to calculate the sensitivity of objective and constraint functions. The sensitivities at both the macroscale and microscale are obtained by considering the interscale coupling effects. Finally, the concurrent bi-level iteration based on the optimality criteria (OC) or the method of moving asymptotes (MMA) is conducted. Through this research, we have illuminated the relations between the optimized performance of the actuator and the material volume fractions at each scale. We have also compared in detail the differences between two-scale and single-scale designs, as well as the differences between the simplified half-symmetric geometric model and the full geometric model. We find that a larger volume fraction of material in either macroscale or microscale generates a larger transmitted displacement magnitude under the same applied electric field, and for a given total material, the transmitted maximum increases with increasing microstructural volume fraction.

压电复合材料作为智能结构器件的重要组成部分，其宏观机电耦合性能往往取决于其微观结构几何形状和材料参数。因此，优化微结构设计对于实现理想的宏观有效性能至关重要。为此，本文通过并行多尺度拓扑优化(To)对压电执行器的材料分布进行优化，以最大限度地实现电能和机械能的传递，满足具体的工程要求。首先，采用能量法对压电材料的微观结构进行均匀化，得到压电材料的有效参数;然后，采用罚极化压电材料法(PEMAP-P)结合伴随法计算目标函数和约束函数的灵敏度。考虑尺度间耦合效应，得到了宏观尺度和微观尺度上的灵敏度。最后，进行了基于最优性准则(OC)或移动渐近线法(MMA)的并行双级迭代。通过本研究，我们阐明了在各个尺度下驱动器的优化性能与材料体积分数之间的关系。我们还详细比较了双比例尺和单比例尺设计的差异，以及简化的半对称几何模型和完整几何模型的差异。研究发现，在相同的外加电场作用下，材料的宏观和微观体积分数越大，传递位移量越大，并且对于一定的总材料，传递位移最大值随微观结构体积分数的增加而增加。

The nonlinear elastic response of bicontinuous rubber blends

Fabio Sozio, François Lallet, Antoine Perriot, Oscar Lopez-Pamies

doi:10.1016/j.ijsolstr.2024.112660

双连续橡胶共混物的非线性弹性响应

Rubber blends are ubiquitous in countless technological applications. More often than not, rubber blends exhibit complex interpenetrating microstructures, which are thought to have a significant impact on their resulting macroscopic mechanical properties. As a first step to understand this potential impact, this paper presents a bottom-up or homogenization study of the nonlinear elastic response of the prominent class of bicontinuous rubber blends, that is, blends made of two immiscible constituents or phases segregated into an interpenetrating network of two separate but fully continuous domains that are perfectly bonded to one another. The focus is on blends that are isotropic and that contain an equal volume fraction (50/50) of each phase. The microstructures of these blends are idealized as microstructures generated by level cuts of Gaussian random fields that are suitably constrained to be periodic so as to allow for the construction of unit cells over which periodic homogenization can be carried out. The homogenized or macroscopic elastic response of such blends are determined both numerically via finite elements and analytically via a nonlinear comparison medium method. The numerical approach makes use of a novel meshing scheme that leads to conforming and periodic simplicial meshes starting from a voxelized representation of the microstructures. Results are presented for the fundamental case when both rubber phases are Neo-Hookean, as well as when they exhibit non-Gaussian elasticity. Remarkably, irrespective of the elastic behavior of the phases, the results show that the homogenized response of the blends is largely insensitive to the specific morphologies of the phases.

橡胶共混物在无数的技术应用中无处不在。通常情况下，橡胶共混物表现出复杂的互穿微观结构，这被认为对其宏观力学性能有重大影响。作为了解这种潜在影响的第一步，本文提出了一种自下而上或均匀化的非线性弹性响应研究，主要研究双连续橡胶共混物，即由两种不混溶的成分或相组成的共混物，这些成分或相分离成两个独立但完全连续的域，它们彼此完美结合。重点是各向同性的混合物，并且每种相的体积分数(50/50)相等。这些混合物的微观结构被理想化为由高斯随机场的水平切割产生的微观结构，这些随机场被适当地约束为周期性的，以便允许构建可以进行周期性均匀化的单元胞。这种共混物的均质或宏观弹性响应通过有限元的数值方法和通过非线性比较介质的解析方法确定。数值方法采用了一种新的网格划分方案，从微观结构的体素化表示开始，得到一致性和周期性的简单网格。给出了两种橡胶相均为新胡克相以及它们表现出非高斯弹性的基本情况的结果。值得注意的是，无论相的弹性行为如何，结果表明共混物的均匀化响应对相的特定形貌基本不敏感。

Rayleigh waves in isotropic elastic materials with micro-voids

Emilian Bulgariu, Ionel-Dumitrel Ghiba, Hassam Khan, Patrizio Neff

doi:10.1016/j.ijsolstr.2024.112661

具有微孔洞的各向同性弹性材料中的瑞利波

In this paper, we show that a general method introduced by Fu and Mielke allows to give a complete answer on the existence and uniqueness of a subsonic solution describing the propagation of surface waves in an isotropic half space modelled with the linear theory of isotropic elastic materials with micro-voids. Our result is valid for the entire class of materials admitting real wave propagation which include auxetic materials (negative Poisson’s ration) and composite materials with negative-stiffness inclusions (negative Young’s modulus). Moreover, the used method allows to formulate a simple and complete numerical strategy for the computation of the solution.

在本文中，我们证明了Fu和Mielke引入的一种一般方法允许给出描述表面波在各向同性半空间中传播的亚音速解的存在性和唯一性的完整答案，该亚音速解是用各向同性弹性材料的线性理论模拟的。我们的结果适用于所有允许真实波传播的材料，包括辅助材料(负泊松比)和具有负刚度夹杂物的复合材料(负杨氏模量)。此外，所使用的方法可以为解的计算制定一个简单而完整的数值策略。

Mechanical Behaviors of Porous Bionic Structure of Lotus Stem

Li Shi, Fuquan Tu, JiaYu Yang

doi:10.1016/j.ijsolstr.2024.112665

莲茎多孔仿生结构的力学行为研究

Lotuses could survive in heavy storms while long and slender lotus stems have porous structure. 12 or 13-wells cross section structure and its distribution along lotus stems were identified by sampling random lotuses from nature. 4 bionic 12-wells structured bars and 1 bionic 13-wells structured bar were fabricated by 3D printing technology with toughness resin. 1 hollow circular tube and 1 hollow square tube were prepared for reference. All the bionic bars and tubes were subjected to three-point bending experiments and transverse loading experiments to investigate mechanical properties referred to the effects of cross section structures and their axial gradient distribution. The results of the transverse loading experiments showed that the peak crushing force (PCF) of the 13-wells original structure (Os-13w) was reduced by about 82.46% and the crushing force efficiency (CFE) was increased by about 300.00% compared with the reference square tube. The results of three-point bending experiments showed that the specific energy absorption (SEA) and CFE of the 12-wells original structure (Os-13w) increased by about 90.71% and 173.33%, respectively, and the PCF decreased by about 29.28% compared with the reference circular tube.Simulation of the experiments explained why the bionic 12-wells structured bar had better mechanical performance than the referenced tubes. In addition, comparisons are made with some novel bionic structures of recent years.

荷花可以在暴风雨中生存，而细长的莲茎具有多孔结构。采用随机抽样的方法，鉴定了12孔和13孔的横截面结构及其沿莲花茎的分布。采用韧性树脂3D打印技术制备了4根仿生12孔结构杆和1根仿生13孔结构杆。制作空心圆管1根，空心方管1根作为对照。通过三点弯曲实验和横向加载实验，研究了受截面结构和轴向梯度分布影响的仿生棒和管的力学性能。横向加载试验结果表明，与参考方管相比，13孔原始结构(Os-13w)的峰值破碎力(PCF)降低了约82.46%，破碎力效率(CFE)提高了约300.00%。三点弯曲实验结果表明，与参考圆管相比，12孔原始结构(Os-13w)的比能吸收(SEA)和CFE分别提高了约90.71%和173.33%，PCF降低了约29.28%。实验模拟解释了为什么仿生12孔结构杆比参考管具有更好的力学性能。并与近年来的一些新型仿生结构进行了比较。

Journal of the Mechanics and Physics of Solids

Representation of stress and free energy for a viscoelastic body from a stressed reference

Soumya Mukherjee, Parag Ravindran

doi:10.1016/j.jmps.2024.105544

用应力参考来表示粘弹性体的应力和自由能

Viscoelastic materials are often initially or residually stressed in the reference configuration. This stress and associated configuration may also evolve temporally without any external influence or loading. This paper develops a general framework representing the stress and Helmholtz potential from a stressed viscoelastic reference configuration. The Helmholtz function is assumed to depend on the initial stress, the initial stress rate (objective), the initial rate of deformation, and the right Cauchy–Green stretch tensor. The corresponding invariants appear not to have been have used earlier. New sets of spectral invariants are also determined and other possible sets of spectral invariants are identified. An appropriate constitutive relation and Helmholtz potential are obtained using a stress-free configuration associated with the stressed reference configuration. For this purpose, the initial strain tensors are determined in terms of initial stress and initial stress-rate by inverting a standard constitutive relation for a viscoelastic material. The model developed using this inverse approach is applied to the investigation of the stress-relaxation of a thick viscoelastic sphere from a stressed reference. Further, it is noted that measuring residual stress is quite challenging for viscoelastic materials. In the context of the present framework, a destructive, and a non-destructive approach to measure residual stress and residual stress-rate for viscoelastic materials is presented.

粘弹性材料通常在参考结构中具有初始应力或残余应力。这种应力和相关的结构也可能在没有任何外部影响或载荷的情况下暂时演变。本文从应力粘弹性参考构型出发，建立了表示应力和亥姆霍兹势的一般框架。假设亥姆霍兹函数依赖于初始应力、初始应力速率(目标)、初始变形速率和右柯西-格林拉伸张量。相应的不变量似乎以前没有使用过。确定了新的谱不变量集，并确定了其他可能的谱不变量集。利用与应力参考构型相关联的无应力构型获得了适当的本构关系和亥姆霍兹势。为此，通过反演粘弹性材料的标准本构关系，确定初始应变张量为初始应力和初始应力率。将该方法建立的模型应用于厚粘弹性球应力松弛的研究。此外，需要注意的是，测量粘弹性材料的残余应力是相当具有挑战性的。在本框架的背景下，提出了一种破坏性和非破坏性的方法来测量粘弹性材料的残余应力和残余应力率。

Stress discontinuity and singularity around the vertex of a triangular inhomogeneity

Chunlin Wu, Huiming Yin

doi:10.1016/j.jmps.2024.105545

不均匀三角形顶点周围的应力不连续和奇异性

The stress field around a vertex of angular inhomogeneity has been investigated by Eshelby’s equivalent inclusion method (EIM). Different from Eshelby’s problem for ellipsoidal inhomogeneity with a uniform or polynomial eigenstrain, a singular eigenstrain field is derived by Airy’s stress function and asymptotic analysis, in which the singular elastic fields can be expressed in terms of the distance to the vertex. The discontinuity of Eshelby’s tensor along the boundary has been analytically derived and are used in the stress equivalence condition at the vertex, which can be converted into an eigenvalue problem with the integral of the Green’s function and singular eigenstrain over the inhomogeneity. To verify the solution, when the opening angle 2β at the vertex approaches zero, the triangular void reduces to a slit-like crack, and the paper reproduces the classic solution of 1/r singularity. When β increases from 0 to π/2, the singularity parameter λ around the vertex of the triangular void reduces at different pace under the symmetric and antisymmetric loading conditions. When a triangular inhomogeneity exhibits nonzero stiffness and different angles, λ changes with the stiffness ratio, β, and loading conditions, and the dominant stress singularity around the vertex and stress discontinuity across the boundary are analytically provided. Particularly, the stress singularity for an adhesive interface with varying stiffness provides insight for structure repair and integration.

Eshelby 的等效包含法（EIM）研究了角度不均匀性顶点周围的应力场。与具有均匀或多项式特征应变的椭球不均匀性的 Eshelby 问题不同，通过 Airy 应力函数和渐近分析得出了奇异特征应变场，其中奇异弹性场可以用到顶点的距离来表示。Eshelby 张量沿边界的不连续性已被分析推导出来，并用于顶点处的应力等效条件，该条件可转化为不均匀性上格林函数和奇异特征应变积分的特征值问题。为了验证该解法，当顶点处的开口角 2β 接近于零时，三角形空隙会减小为狭缝状裂缝，本文再现了 1/r 奇异性的经典解法。当 β 从 0 增大到 π/2 时，在对称和非对称加载条件下，三角形空隙顶点周围的奇异参数 λ 以不同的速度减小。当三角形不均匀体表现出非零刚度和不同角度时，λ 会随着刚度比 β 和加载条件的变化而变化，顶点周围的主要应力奇异性和边界上的应力不连续性都是通过分析得到的。特别是刚度变化的粘合界面的应力奇异性为结构修复和整合提供了启示。

Mechanics of Materials

Numerical modelling of multi-directional thin-ply carbon/glass hybrid composites with open holes under tension

J.D. Acosta, Guillermo Idarraga, P. Maimí, Meisam Jalalvand, J.M. Meza

doi:10.1016/j.mechmat.2024.104921

多向开孔薄层碳/玻璃复合材料张力作用下的数值模拟

Many researchers have used continuum damage mechanics for modelling damage in standard composites. This approach is intrinsically suitable for modelling the progress of damage modes spread over the specimen, which has been widely reported in pseudo-ductile hybrid composites. To the authors' best knowledge, this paper is the first numerical model based on continuum damage mechanics proposed for pseudo-ductile hybrid composites. The proposed constitutive model uses a thermodynamically consistent approach to compute the damage progression in the material. Experimental stress-strain curves and the failure pattern of carbon/glass hybrid lay-ups with gradual failure taken from the literature are compared against the numerical results to validate the model. The model provides a mesh-independent solution with a good prediction of the damage sequence and the overall stress-strain curves of the notched samples. A good correlation in size, location and type of damage mechanism was found between numerical and experimental results. This study indicates that the proposed model can provide a good prediction of the onset and propagation of the damage in notched hybrid composite laminates.

许多研究者使用连续损伤力学来模拟标准复合材料的损伤。这种方法本质上适合于模拟损伤模式在试样上的扩散过程，这在伪延性混杂复合材料中已经得到了广泛的报道。据作者所知，本文是第一个基于连续损伤力学的伪延性混杂复合材料数值模型。提出的本构模型使用热力学一致的方法来计算材料的损伤进展。将文献中得到的碳/玻璃混合层的应力-应变实验曲线和逐渐破坏的破坏模式与数值结果进行了对比，验证了模型的有效性。该模型提供了一个网格无关的解，可以很好地预测缺口样品的损伤序列和整体应力-应变曲线。数值结果与实验结果在损伤的大小、位置和类型上具有较好的相关性。研究表明，该模型能较好地预测缺口复合材料层合板损伤的发生和扩展过程。

International Journal of Plasticity

High–strain–rate deformation of a nanoprecipitate–strengthened dual–phase steel

Yongzheng Yu, Yang Zhang, Songsong Xu, Jihong Han, Junpeng Li, Chunhuan Guo, Fengchun Jiang, Gang Zhao, Zhongwu Zhang

doi:10.1016/j.ijplas.2024.103887

纳米沉淀强化双相钢的高应变速率变形

High–strain–rate deformation of steels is prone to generating localized adiabatic shear bands (ASB) due to strain localization, leading to plastic instability and fracture. Nanoprecipitate–strengthened austenite–martensite dual–phase (DP) steel is a kind of promising impact–resistant materials due to their high strength and excellent plasticity. In this study, the effects of a combination of nanoprecipitates and the frame structure of DP steels with the hard martensite as the support framework on the dynamic mechanical properties were systematically investigated. The nanoprecipitate–strengthened DP steel exhibited excellent dynamic performance. At a strain rate of 3800 s−1, the maximum flow stress of the DP steel with nanoprecipitates reached ∼ 4067 MPa, which was 1146 MPa higher than its counterpart without nanoprecipitates. High–strain–rate deformation induced the transformation of Cu–rich nanoprecipitates from body–centered cubic (B2) to 9R twin structure, alleviating the stress concentration. Upon high–strain–rate deformation, the high strength of nanoprecipitate–strengthened DP steel induced the formation of a narrow shear band with sever–deformed microstructure. The frame–structure of DP steel restrained the transformation of deformed shear bands (DSB) to transformed shear bands (TSB) due to the deformation–induced martensitic transformation of austenite, delaying the crack formation and propagation.

钢的高应变速率变形容易因应变局部化而产生局部绝热剪切带(ASB)，从而导致塑性失稳和断裂。纳米沉淀强化奥氏体-马氏体双相钢因其高强度和优异塑性而成为一种很有发展前途的抗冲击材料。本研究系统地研究了以硬马氏体为支撑框架的DP钢的框架结构与纳米沉淀相结合对动态力学性能的影响。纳米沉淀增强DP钢具有良好的动态性能。在应变速率为3800 s−1时，含纳米沉淀的DP钢的最大流变应力达到~ 4067 MPa，比未含纳米沉淀的DP钢高1146 MPa。高应变速率变形诱导富cu纳米沉淀物由体心立方(B2)转变为9R孪晶结构，减轻了应力集中。在高应变速率变形时，高强度的纳米析出体增强DP钢形成了窄剪切带，具有严重变形的显微组织。由于变形诱发奥氏体马氏体转变，DP钢的框架结构抑制了变形剪切带(DSB)向变形剪切带(TSB)的转变，延缓了裂纹的形成和扩展。

A microdamage model for FCC single crystals considering a mixed failure mechanism of slip and cleavage

Ao Li, Weiping Hu, Yuanlong Yang, Kun Li, Hongyu Tian, Zhixin Zhan, Qingchun Meng

doi:10.1016/j.ijplas.2024.103888

考虑滑移和解理混合破坏机制的FCC单晶微损伤模型

In this study, a microdamage model is newly proposed to predict the failure process of FCC single crystals. Two micro damage mechanisms, slip and cleavage, are both involved in the model. A microscopic damage variable is first defined at the slip plane scale, and a damage coupled crystal plasticity constitutive equation in a co-rotational tensor framework is then established. A damage driving force consisting of generalized energies related to the resolved shear stress and the positive resolved normal stress is proposed to reflect the mixed failure mechanism of FCC single crystals induced by slip and cleavage. The damage evolution equation is then derived in the framework of thermodynamics. An explicit algorithm for the damage coupled crystal plasticity finite element method is given. The proposed microdamage model is utilized to predict the slip-dominant fracture behavior of a single crystal copper and the cleavage-dominant fracture behavior of a nickel-based single crystal alloy. The damage evolution process of slip planes is given and the influence mechanism is revealed. The calculated results agree well with the experimental data, which verifies the good capability of the proposed model in describing and predicting the multi failure processes of FCC metals. Finally, a 2D fracture simulation of a single crystal notched specimen under shear loading is conducted, and the effect of damage parameters on the fracture modes is also discussed.

本文提出了一种预测FCC单晶失效过程的微损伤模型。该模型涉及滑移和解理两种微观损伤机制。首先在滑移面尺度上定义微观损伤变量，然后在共旋张量框架下建立损伤耦合晶体塑性本构方程。提出了一种由分解剪应力和正分解正应力相关的广义能量组成的损伤驱动力，以反映FCC单晶由滑移和解理引起的混合破坏机制。在热力学框架下推导了损伤演化方程。给出了损伤耦合晶体塑性有限元法的显式算法。利用该微损伤模型预测了单晶铜的以滑移为主断裂行为和镍基单晶合金的以解理为主断裂行为。给出了滑移面的损伤演化过程，揭示了滑移面的影响机理。计算结果与实验数据吻合较好，验证了该模型对FCC金属多失效过程的描述和预测能力。最后，对单晶缺口试件在剪切载荷作用下的二维断裂进行了模拟，并讨论了损伤参数对断裂模式的影响。

Thin-Walled Structures

Machine learning-based real-time velocity prediction of projectile penetration to carbon/aramid hybrid fiber laminates

Yu Wang, Weifu Sun

doi:10.1016/j.tws.2024.111600

基于机器学习的弹丸侵彻碳纤维/芳纶复合材料的实时速度预测

Composite laminates subjected to dynamic impacts are usually investigated by experimental or numerical techniques. Numerical simulations, as an excellent complementary tool to experiments, are capable of reproducing microscopic results that cannot be observed in experiments, but require time-consuming calculations. Therefore, this work demonstrates the capability and efficiency of neural networks and decision tree models for the real-time prediction of projectile penetration of aramid/carbon hybrid fiber laminates impacted at variable angles for different initial velocities. To obtain accurate prediction models, a combination of experimental and finite element methods has been adopted and the experimentally validated finite element models have been used to provide data for training the prediction models. Consequently, the prediction model is able to accurately predict the residual velocity after projectile penetration of unknown hybrid laminates. The research demonstrates that using a large dataset generated by finite element analysis can help the prediction model to give more accurate predictions. The decision tree model outperforms the neural network model in known datasets, but the neural network model has better generalization capabilities of handling unknown feature inputs and giving accurate results.

复合材料层压板受动力冲击的研究通常采用实验或数值方法。数值模拟作为实验的一种很好的补充工具，能够再现实验中无法观察到的微观结果，但需要耗费大量的计算时间。因此，本研究证明了神经网络和决策树模型用于实时预测不同初速度下变角度冲击的芳纶/碳纤维复合材料的弹丸穿深的能力和效率。为了获得准确的预测模型，采用实验与有限元相结合的方法，并利用实验验证的有限元模型为预测模型的训练提供数据。因此，该预测模型能够准确预测未知混合层合板弹丸侵彻后的剩余速度。研究表明，利用有限元分析生成的大型数据集可以帮助预测模型给出更准确的预测。决策树模型在已知数据集上优于神经网络模型，但神经网络模型在处理未知特征输入和给出准确结果方面具有更好的泛化能力。

Experimental study on fragments dispersion characteristics of elliptical cross-section casing under explosive loading

Yuxuan Deng, Xianfeng Zhang, Chuan Xiao, Chuang Liu, Junwei Liu, Pengcheng Li, Mengting Tan, Wei Xiong

doi:10.1016/j.tws.2024.111601

爆炸载荷作用下椭圆截面机匣破片弥散特性试验研究

To better understand the fragments dispersion characteristics of elliptical cross-section warhead (ECSW), static explosion experiments were conducted with four ECSWs and one circular cross-section warhead (CCSW). The warheads were designed with the same mass ratio of charge to the metal casing, and the difference in cross-section shape was indicated by the shape ratio. The experimental results indicated that ECSW fragments dispersion in their radial direction deviated from the normal direction of casing under explosive loading. The radial deviation angle decreased with the higher shape ratios. In the axial direction, the axial projection angle of fragment increased gradually from the major to the minor axis. Additionally, the fragment velocity and density in the minor axis direction increased noticeably compared to the major axis, and the difference reduced as the shape ratio increased. A formula for predicting the radial velocity distribution of the fragments was proposed, and the maximum relative error between the calculation and experiment results is less than 5%. Finally, the driving mechanism of ECSW was preliminarily revealed. The findings serve as a fundamental basis for future research on ECSW and offer valuable insights for the development of innovative warhead designs.

为了更好地了解椭圆截面战斗部破片弥散特性，采用4枚椭圆截面战斗部和1枚圆形截面战斗部进行了静态爆炸试验。采用相同装药质量比设计弹头，用形状比表示弹头截面形状的差异。实验结果表明，在爆炸载荷作用下，ECSW破片径向弥散偏离机匣法向。随着形状比的增大，径向偏差角减小。在轴向上，破片轴向投影角度由长轴向小轴逐渐增大。短轴方向破片速度和密度较长轴方向明显增大，且随形状比的增大而减小。提出了一种预测破片径向速度分布的公式，计算结果与实验结果的最大相对误差小于5%。最后，初步揭示了ECSW的驱动机理。研究结果为未来的ECSW研究奠定了基础，并为创新战斗部设计的发展提供了宝贵的见解。

Elastic Size Effect of Single Crystal Copper Beams under Combined Loading of Torsion and Bending

Jae-Hoon Choi, Hyemin Ryu, Gi-Dong Sim

doi:10.1016/j.tws.2024.111602

扭转和弯曲复合载荷下单晶铜梁的弹性尺寸效应

Among various strain gradient theories, the modified couple stress theory, which introduces a single length scale parameter as an additional material property, has garnered significant interest owing to its simplified portrayal of the material behavior. In this study, we investigated whether a single length scale parameter is sufficient to predict the mechanical behavior under two different type of strain gradients: torsion and bending. L-shaped beams made of single crystal copper with thicknesses ranging from 2.4 μm to 9.1 μm were fabricated, and loads were applied using an indenter. The contributions of bending and torsion were controlled by adjusting the loading position, and size effect was observed under these conditions. Through these experiments, we demonstrated the existence of elastic size effect of single crystalline materials under strain gradients. Specifically, size effect was observed in both bending and torsion, with a larger effect observed in cases closer to pure bending. Moreover, we report that the modified couple stress theory and the modified strain gradient theory are not applicable for simulating size effect under combined loading. This discovery highlights the necessity for the development of a new theory capable of adequately simulating size effects under the intricate loading scenarios encountered in practical applications.

在各种应变梯度理论中，引入单一长度标度参数作为附加材料属性的修正耦合应力理论因其对材料行为的简化描述而备受关注。在本研究中，我们研究了单一长度标度参数是否足以预测两种不同应变梯度下的机械行为：扭转和弯曲。我们制作了厚度从 2.4 μm 到 9.1 μm 的单晶铜 L 形梁，并使用压头施加载荷。通过调整加载位置控制了弯曲和扭转的贡献，并在这些条件下观察到了尺寸效应。通过这些实验，我们证明了单晶材料在应变梯度下存在弹性尺寸效应。具体来说，在弯曲和扭转中都观察到了尺寸效应，在更接近纯弯曲的情况下观察到了更大的效应。此外，我们还报告了修正的耦合应力理论和修正的应变梯度理论不适用于模拟组合加载下的尺寸效应。这一发现凸显了开发一种新理论的必要性，该理论能够充分模拟实际应用中遇到的复杂加载情况下的尺寸效应。

Low-Damage Performance of Blast Resilient Steel Rocking Column Base with Friction Connection

Rui Zhang, Junrong Liu, Jiapei Xu, Liang-Jiu Jia

doi:10.1016/j.tws.2024.111598

带摩擦连接的爆炸弹性钢摇柱底座的低损伤性能

This paper presents an experimental and numerical study on the dynamic response and blast resilience of a low-damage rocking column base under blast loading. A conventional rigid column base was used as a reference for comparison. A novel test setup was designed to reflect the actual force state of the column base in an explosive environment. During the test, the column was subjected to a constant axial force with a compression ratio of 0.17. Under the blast loading with a scaled distance of 0.43 m·kg−1/3, the rocking column base exhibited remarkable low-damage and self-centering characteristics, with a maximum equivalent plastic strain of 0.01 and a residual deformation of 0.07%. In contrast, the rigid one suffered irreparable local buckling, resulting in a residual deformation of 3.74%. The results demonstrate that the rocking column base effectively mitigates internal forces through controlled rocking motion and dissipates input energy mainly through frictional sliding. This approach proves to be highly effective in enhancing blast resilience. Finally, a refined finite element analysis (FEA) model was developed to quantitatively evaluate the deformation mode and damage of the joints, based on which the low-damage characteristic of the rocking column base was verified.

本文对爆炸荷载作用下低损伤摇柱基础的动力响应和爆炸回弹性进行了试验和数值研究。以常规刚性柱基础为参照进行比较。设计了一种新的测试装置，以反映爆炸环境下柱基座的实际受力状态。试验过程中，柱承受恒定轴向力，压缩比为0.17。在标度距离为0.43 m·kg−1/3的爆炸荷载作用下，摇摆柱底部表现出显著的低损伤自定心特性，最大等效塑性应变为0.01，残余变形为0.07%。而刚性试件则存在不可修复的局部屈曲，残余变形为3.74%。结果表明，摇摆柱基座通过控制摇摆运动有效地减轻内力，主要通过摩擦滑动来耗散输入能量。事实证明，这种方法在提高爆炸回弹方面是非常有效的。最后，建立了精细化的有限元分析模型，对节点的变形模式和损伤进行了定量评价，并在此基础上验证了摇柱基座的低损伤特性。