今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 3 篇，Thin-Walled Structures 2 篇International Journal of Solids and StructuresOrigin of bent ridge-kink based on disclination relaxationXueyu Zhang, Ryutaro Matsumura, Yuri Shinohara, Tomonari Inamuradoi:10.1016/j.ijsolstr.2024.112829 基于偏斜松弛的弯曲脊扭成因In this study, we have developed a geometric model for bent kinks by introducing sequences of ortho-connected kink bands into ridge-kinks to provide insights into the possible reasons why kinks are bent and the resulting geometry when they are bent. We first formulated the Frank angles and coordinates of the disclinations formed in the bent kinks, which enable our discussion on the influence of the introduction of ortho-kinks on the Gibbs energy by utilizing Romanov’s disclination model. It turns out that the introduction of ortho-kinks can relax the elastic strain energy and thus reduce the Gibbs energy of the system under compression states with lower external stresses. On the other hand, the introduction of ortho-kinks increases the Gibbs energy at higher compression stresses, implying sharp ridge-kinks are preferred under such conditions. This trend resembles the experimental observations reported by previous studies that the shapes of newly formed kinks tend to transition from pre-kinks with bent shapes to ridge-kinks with sharp shapes as the compression test progresses. The smoothly bent kink with smoothly distributed misorientation, formed by increasing the number of introduced ortho-kinks, can further reduce the Gibbs energy at lower applied stresses. Subsequently, based on the Rank-1 condition for the connection of kink bands, we further analyzed the geometry of such smoothly bent kinks and derived the analytical equations for the constraints on the orientation distribution. Finally, we conducted EBSD measurements on bent kinks observed in directionally solidified (DS) LPSO-Mg alloys and confirmed that the derived equations for the orientation distribution are in good agreement with the experimental results.在这项研究中，我们通过将正交连接的扭结带序列引入脊状扭结中，开发了弯曲扭结的几何模型，以深入了解扭结弯曲的可能原因以及弯曲时产生的几何形状。我们首先给出了弯曲扭结中形成的斜折的Frank角和坐标，这使得我们能够利用罗曼诺夫的斜折模型讨论正扭结的引入对吉布斯能量的影响。结果表明，正交扭结的引入可以使体系的弹性应变能松弛，从而降低体系在低外应力压缩状态下的吉布斯能。另一方面，在较高的压缩应力下，正扭结的引入增加了吉布斯能，这意味着在这种条件下，尖锐的脊状扭结是首选的。这一趋势与以往研究报告的实验观察结果相似，即随着压缩试验的进行，新形成的扭结的形状倾向于从弯曲形状的预扭结转变为尖锐形状的脊状扭结。在较低的外加应力下，通过增加引入的正扭结的数量，形成具有平滑分布的错取向的平滑弯曲扭结，可以进一步降低吉布斯能。随后，基于扭结带连接的Rank-1条件，进一步分析了这种光滑弯曲扭结的几何形状，并推导了其方向分布约束的解析方程。最后，我们对定向凝固(DS) LPSO-Mg合金中观察到的弯曲扭结进行了EBSD测量，证实了取向分布的推导方程与实验结果吻合较好。Journal of the Mechanics and Physics of SolidsQuantized Impact of Rod on PlateQing Peng, Xiaoming Liu, Yue-Guang Weidoi:10.1016/j.jmps.2024.105680 量化杆对板的影响In this work, we attacked the problem of elastic impact of a rod on a plate. By considering wave propagation on the plate and along the rod, we established a mathematic model with delay differential equation that governs such impact. The proposed model could consolidate classical impact problems from bead-on-wall, bead-on-plate, to rod-on-wall impact. Solving the governing equation, we obtained a universal loading and unloading history of such impact: the unloading history exhibits quantized plateaus, the values of which are quantitatively provided in the present study. Also, the contact duration also shows a band structure while tuning the compliance of plate. In addition, we analyzed the overshoots leading the plateaus during unloading, which cause the final detachment between the rod and the plate.在这项工作中，我们研究了杆对板的弹性冲击问题。考虑波在板上和杆上的传播，建立了控制这种影响的时滞微分方程数学模型。所提出的模型可以将经典的碰撞问题从头对壁、头对板到杆对壁进行整合。通过求解控制方程，我们得到了这种冲击的普遍加载和卸载历史:卸载历史表现为量化的平台，本研究定量地提供了其值。同时，在调整板的柔度时，接触时间也呈现带状结构。此外，我们分析了在卸载过程中导致平台的超调，这导致杆与板之间的最终脱离。Mechanics of MaterialsPredicting plastic behavior of magnesium alloy tube bending with comprehensive constitutive modelsHan-Xu Zhang, Fei-Fan Li, Gang Fangdoi:10.1016/j.mechmat.2024.105030 用综合本构模型预测镁合金管材弯曲塑性行为This paper aims to predict defects occurring in magnesium alloy tube bending through finite element simulations. Deformation tests were conducted to identify and characterize plastic anisotropy, tension-compression asymmetry, and differential hardening behaviors of extruded Mg–Al–Zn-RE alloy rectangular tubes. Limited by size, the deformation tests along the wall thickness of specimens are conducted through crystal plasticity analysis. To thoroughly investigate the material constitutive features affecting bending, two constitutive models, Yoon2014 and Hill48, are established and calibrated. The non-associative flow rule is adopted, and differential hardening is depicted using the yield-surface interpolation method. In comparison, the Yoon2014 model accurately predicts the strain distribution and tube shape collapse of the bent tube with negligible deviation from the experimental data, prior to the Hill48 model. This underscores the necessity of considering comprehensive plasticity models in tube bending simulations.本文旨在通过有限元模拟对镁合金管材弯曲过程中出现的缺陷进行预测。通过变形试验确定和表征挤压Mg-Al-Zn-RE合金矩形管的塑性各向异性、拉压不对称性和不同硬化行为。受尺寸限制，沿试样壁厚方向的变形试验采用晶体塑性分析方法进行。为了深入研究影响弯曲的材料本构特征，建立并校准了Yoon2014和Hill48两个本构模型。采用非关联流动规律，采用屈服面插值法描述微分硬化。相比之下，Yoon2014模型较Hill48模型更准确地预测了弯曲管的应变分布和管形坍塌，与实验数据的偏差可以忽略不计。这强调了在管材弯曲模拟中考虑综合塑性模型的必要性。International Journal of PlasticityOrientation-dependent deformation mechanisms of alpha-uranium single crystals under shock compressionYongfeng Huang, Pan Li, Songlin Yao, Kun Wang, Wangyu Hudoi:10.1016/j.ijplas.2024.103991激波压缩下α -铀单晶取向依赖性变形机制Large-scale non-equilibrium molecular dynamics (NEMD) simulations were employed to investigate the dynamic deformations of alpha-uranium (α-U) single crystals subjected to varying shock strengths along low-index crystallographic orientations. The pronounced anisotropy of α-U gives rise to a complex microstructural evolution under shock loading. In-depth microstructural analysis of post-shock specimens reveals the identification of multiple dynamic deformation mechanisms. Notably, when the shock loading direction aligns with the a-axis, dynamic deformation of the α-U single crystals is primarily dominated by lattice instability, which attributes to a crystalline-to-amorphous transition serving as the dominant shear stress relaxation pathway. On the other hand, shock loading along the b-axis results in an abundance of deformation twins, with twinning planes identified as (130) and (13¯0). During the twinning event, the α-U matrix undergoes a transition to a metastable intermediate phase, subsequently decomposing into a composite structure comprising α-U twins and matrix. This unconventional twinning mechanism significantly deviates from classical theories. Furthermore, upon loading along the c-axis, twinning and a phase transition from α-U to body-centered tetragonal phase (bct-U) occur in α-U single crystal samples. Given that the pressure threshold of this phase transition predicted by ab initio calculations is as high as ∼270 GPa, the phase transition from α-U to bct-U might be implausible. An alternative interatomic potential of uranium with the higher pressure threshold was employed to reinvestigate the shock response of α-U single crystals along the c-axis. The phase transition of α-U to bct-U disappears, and twinning dominates the plastic deformation, with the twinning orientation conforming to the {112} twinning. The strong anisotropy of the α-U lattice triggers a wealth of orientation-dependent dynamic deformation mechanisms. The activation of the twinning system is evidently associated with the loading direction, constituting the potential cause for the discovery of multiple twinning variants during the deformation in polycrystalline uranium.采用大规模非平衡分子动力学（NEMD）模拟研究了α-铀（α-U）单晶体在不同冲击强度下沿低指数晶体学取向的动态变形。α-U具有明显的各向异性，因此在冲击加载下会产生复杂的微观结构演变。通过对冲击后试样进行深入的微观结构分析，发现了多种动态变形机制。值得注意的是，当冲击加载方向与 a 轴一致时，α-U 单晶的动态变形主要由晶格不稳定性主导，这就导致晶体到非晶体的转变成为剪应力松弛的主要途径。另一方面，沿 b 轴的冲击加载导致了大量的变形孪晶，孪晶平面被识别为 (130) 和 (13¯0)。在孪生过程中，α-U 基体过渡到一个可蜕变的中间相，随后分解为由α-U孪晶和基体组成的复合结构。这种非传统的孪生机制大大偏离了经典理论。此外，在沿 c 轴加载时，α-U 单晶样品中会出现孪晶，并发生从α-U 到体心四方相（bct-U）的相变。鉴于根据原子序数计算预测的这种相变的压力阈值高达 ∼270 GPa，从 α-U 到 bct-U 的相变可能是难以置信的。我们采用了另一种具有更高压力阈值的铀原子间势来重新研究 α-U 单晶沿 c 轴的冲击响应。α-U到bct-U的相变消失了，孪晶主导了塑性变形，孪晶取向符合{112}孪晶。α-U晶格的强各向异性引发了大量取向相关的动态变形机制。孪晶系统的激活显然与加载方向有关，这也是在多晶铀变形过程中发现多种孪晶变体的潜在原因。Spatially-resolved cluster dynamics modeling of irradiation growthMatthew Maron, Yang Li, Inam Lalani, Kristopher Baker, Benjamin Ramirez Flores, Thomas Black, James Hollenbeck, Nasr Ghoniem, Giacomo Podoi:10.1016/j.ijplas.2024.103989辐射生长的空间分辨簇动力学模拟We develop here a spatially resolved, three-dimensional continuum model coupling cluster dynamics (SR-CD) and crystal plasticity to investigate irradiation growth in zirconium. The model uses scale separation to divide the population of the irradiation cluster into mobile and immobile families. Small interstitial and vacancy clusters are modeled using anisotropic reaction–diffusion. Among the immobile clusters, an atomistically-informed vacancy cluster to vacancy loop transition is taken into account. The coupling between the evolution equation of CD and the plastic deformation of the material is two-fold, with stress-informed bias factors and local inelastic strains computed from the evolution of the evolving cluster population. The numerical implementation of the model utilizes the finite element method to analyze both single-crystal and polycrystalline samples. The growth strains that are computed align well with the experimental data provided by Carpenter for single-crystal Zr. Furthermore, the transformation of a vacancy cluster into a complete vacancy loop, occurring at a size of 14 nm, is in agreement with experimental observations and atomistic simulations. The density, size, and growth rate of the dislocation loops, denoted as〈c〉and 〈a〉, also exhibit good agreement with transmission electron microscopy (TEM) analysis of irradiated Zr and its alloys. Our findings demonstrate there is a spatial correlation of the growth of these dislocation loops and growth strains are significantly influenced by crystal size. To explain the expansion of the 〈a〉 axis and the contraction of the 〈c〉 axis in irradiated Zr, it is necessary to consider the diffusion anisotropy difference (DAD) of mobile interstitial species. We have shown that the PWR Kearns parameters, specifically fr = 0.63, ft = 0.32, fa = 0.05, confer enhanced irradiation resistance to Zr along the principal directions when compared to single crystals. Additionally, reducing the grain size to nanograins further enhances the resistance to irradiation-induced growth, particularly along the direction with the highest volume fraction of basal poles [0001].我们在此建立了一个空间分辨的三维连续模型，该模型将团簇动力学（SR-CD）和晶体塑性耦合在一起，用于研究锆的辐照生长。该模型利用尺度分离将辐照簇群划分为移动和不移动家族。小的间隙簇和空位簇采用各向异性反应扩散模型。在不动簇中，考虑了原子信息空位簇到空位环的转变。CD 演化方程与材料塑性变形之间的耦合是双重的，应力偏置因子和局部非弹性应变是通过不断演化的团簇群体的演化计算得出的。该模型的数值实现采用了有限元方法，以分析单晶和多晶样品。计算出的生长应变与 Carpenter 提供的单晶锆的实验数据非常吻合。此外，一个空位簇转变为一个完整的空位环（大小为 14 纳米）与实验观察和原子模拟结果一致。以〈c〉和〈a〉表示的位错环的密度、尺寸和生长率也与辐照锆及其合金的透射电子显微镜（TEM）分析结果十分吻合。我们的研究结果表明，这些位错环的生长存在空间相关性，生长应变受到晶体尺寸的显著影响。要解释辐照锆中〈a〉轴的扩展和〈c〉轴的收缩，有必要考虑移动间隙物种的扩散各向异性差（DAD）。我们的研究表明，与单晶体相比，PWR Kearns 参数（特别是 fr = 0.63、ft = 0.32、fa = 0.05）可增强锆沿主要方向的抗辐照能力。此外，将晶粒尺寸减小到纳米晶粒可进一步增强抗辐照诱导生长的能力，尤其是沿基极体积分数最高的方向[0001]。Effect of Ni4Ti3 precipitates on the functional properties of NiTi shape memory alloys: A phase field studyBo Xu, Yuanzun Sun, Chao Yu, Jiachen Hu, Jiaming Zhu, Junyuan Xiong, Qianhua Kan, Chong Wang, Qingyuan Wang, Guozheng Kangdoi:10.1016/j.ijplas.2024.103993Ni4Ti3析出物对NiTi形状记忆合金功能性能影响的相场研究Ni4Ti3 precipitates, which generally exist in aged Ni-rich NiTi shape memory alloys (SMAs), can have a profound effect on material properties. However, the fundamental insights into the effects of Ni4Ti3 precipitates on the functional properties, including the superelasticity (SE), elastocaloric effect (eCE), and shape memory effects (SMEs), are not well understood yet, especially those originating from the B2-B19′ martensite transformation (MT). In this work, a phase field model coupling the precipitation of Ni4Ti3 and the B2-B19′ MT is proposed, where the thermo-mechanical coupling effect and grain size effect are considered. The precipitate-dependent SE, eCE, one-way SME (OWSME), and stress-assisted two-way SME (SATWSME) of single-crystal, polycrystalline, and gradient-nanograined NiTi SMAs are simulated. The effects of the precipitate density, grain orientation range (texture), and gradient-distributed precipitate are examined, and the underlying microscopic mechanisms are revealed. The simulation results and new findings not only contribute to a more comprehensive insight into the effect of Ni4Ti3 precipitates on the MT, martensite reorientation, and functional properties of NiTi SMAs but also provide a reference for the development of excellent SMA-based solid refrigerants or SMA smart materials with designable functional properties.Ni4Ti3析出物普遍存在于时效富镍NiTi形状记忆合金中，对材料性能有着深远的影响。然而，Ni4Ti3析出物对功能性能的影响，包括超弹性(SE)、弹性热效应(eCE)和形状记忆效应(SMEs)，特别是那些源自B2-B19′马氏体相变(MT)的影响，尚未得到很好的理解。本文建立了考虑热-机械耦合效应和晶粒尺寸效应的Ni4Ti3与B2-B19′MT相场耦合模型。模拟了单晶、多晶和梯度纳米NiTi sma的沉淀依赖SE、eCE、单向SME (OWSME)和应力辅助双向SME (SATWSME)。考察了析出相密度、晶粒取向范围(织构)和梯度分布的影响，揭示了其微观机制。模拟结果和新发现不仅有助于更全面地了解Ni4Ti3沉淀对NiTi SMA的MT、马氏体重取向和功能性能的影响，而且为开发具有可设计功能性能的优异SMA固体制冷剂或SMA智能材料提供参考。Thin-Walled StructuresLow temperature effect on cyclic behavior of shape memory alloy U-shaped dampersJiahao Huang, Zhipeng Chen, Songye Zhudoi:10.1016/j.tws.2024.111962低温对形状记忆合金u型阻尼器循环性能的影响Although Nickel-Titanium (NiTi) shape memory alloys (SMAs) have been widely studied as seismic response mitigation devices in civil structures, their temperature sensitivity due to the coupled thermo-mechanical behavior prevents their practical implementation in cold temperature environments. This paper investigated the effects of varying ambient temperatures (particularly low ambient temperature) on the hysteretic behavior and self-centering (SC) ability of shape memory alloy U-shaped dampers (SMAUDs) that were made of NiTi showing superelasticity (SE) at room temperature. Thermo-mechanical properties of SMAUDs were identified through differential scanning calorimetry (DSC) tests. Cyclic loading experiments on SMAUDs were conducted at a wide ambient temperature range from −40°C to 20°C. The variations in the hysteretic characteristics of the SMAUD, including partial superelasticity (SE), strength, stiffness, SC, and energy dissipation capabilities, at different ambient temperatures were investigated. In general, the decreasing ambient temperature leads to the degradation of the SC ability. At ambient temperatures below the phase transformation temperature, the SMAUDs lose the SE but still maintain certain levels of strength and energy dissipation, which is different from common axial-type SMA elements. Meanwhile, the SMAUDs can restore their SC ability and strength after the recovery from low temperatures to room temperature, making them suitable for use in a cold environment.尽管镍钛(NiTi)形状记忆合金(SMAs)作为土木结构中的地震反应缓解装置已经得到了广泛的研究，但由于热-力耦合行为导致的温度敏感性阻碍了它们在低温环境中的实际应用。研究了室温下不同环境温度(特别是低温)对具有超弹性的NiTi形状记忆合金u型阻尼器(SMAUDs)滞回性能和自定心(SC)能力的影响。通过差示扫描量热法(DSC)测试鉴定了SMAUDs的热力学性能。SMAUDs的循环加载实验在- 40℃~ 20℃的宽环境温度范围内进行。研究了不同环境温度下SMAUD的滞回特性，包括部分超弹性(SE)、强度、刚度、SC和耗能能力的变化。一般来说，环境温度的降低会导致SC能力的下降。在低于相变温度的环境温度下，smaud失去了SE，但仍保持一定水平的强度和能量耗散，这与普通轴向型SMA元件不同。同时，smaud从低温恢复到室温后，可以恢复其SC能力和强度，适合在寒冷环境中使用。Effect of bondline thickness on the mechanical performance of CFRP laminate with asymmetric damage repaired by double-sided adhesive patchXiao Han, Daoxin Li, Liangliang Sun, Dezhi Wang, Jiewang Xu, Wei Zhangdoi:10.1016/j.tws.2024.111976粘结线厚度对双面胶贴修复不对称损伤CFRP复合材料力学性能的影响As a common CFRP repair method, double-sided adhesive patch has been widely used in the automotive and aeronautic industry. More specific research is thus needed to help better understanding the effect of repairing parameters on the mechanical performance of CFRP structures after patch bonding. In this paper, experimental and Finite Element Modelling (FEM) efforts were made on the adhesive repaired CFRP laminate with different bondline thicknesses. Artificial damage was prefabricated in the centre of the CFRP laminate, which was then repaired through double-sided adhesive patch. Quasi-static tensile tests were conducted on the repaired specimen up to failure, to obtain the load-displacement curves. With a bondline thickness of 0.5 mm, the repaired CFRP structure reached its maximum peak load, increased by 25.3% and 26.4% compared to 0.2 mm and 1.0 mm bondline thicknesses, respectively. SEM observations were used to analyse the influence of adhesive thickness on the fracture modes. Combined with Cohesive Zone Model (CZM) for the adhesive layer and Hashin damage criterion for the CFRP, the FE model of the CFRP laminate repaired with double-sided adhesive patch subjected to tensile loading was established. Finally, the damage evolution as well as the failure modes in the parent laminate and adhesive layer with different bondline thicknesses were compared and analysed. It was revealed that bondline thickness can effectively affect the mechanical performance of CFRP laminate after adhesive patch repair.双面粘接贴片作为一种常用的CFRP修补方法，在汽车和航空工业中得到了广泛的应用。因此，需要更具体的研究来帮助更好地了解修复参数对贴片粘合后CFRP结构力学性能的影响。本文对不同粘结线厚度的CFRP粘接修复层合板进行了实验和有限元模拟研究。在CFRP层压板的中心预制人工损伤，然后通过双面胶贴修复。对修复试件进行了破坏前的准静态拉伸试验，得到了试件的载荷-位移曲线。修复后的CFRP结构在粘结线厚度为0.5 mm时达到最大峰值载荷，比粘结线厚度为0.2 mm和1.0 mm时分别增加了25.3%和26.4%。利用扫描电镜分析了胶粘剂厚度对断裂模式的影响。结合粘接层的内聚区模型(CZM)和CFRP的哈辛损伤准则，建立了双面粘接修补CFRP层合板在拉伸载荷作用下的有限元模型。最后，对不同粘结线厚度的母层和粘结层的损伤演化及破坏模式进行了比较分析。结果表明，粘结线厚度对贴片修复后CFRP复合材料的力学性能有显著影响。来源：复合材料力学仿真Composites FEM
