今日更新：Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 6 篇

Mechanics of Materials

Elucidating the impact of microstructure on mechanical properties of phase-segregated polyurea: Finite element modeling of molecular dynamics derived microstructures

Yang Steven J., Rosenbloom Stephanie I., Fors Brett P., Silberstein Meredith N.

doi:10.1016/j.mechmat.2023.104863

阐明微观结构对相分离聚脲机械性能的影响：分子动力学衍生微观结构的有限元建模

Phase-segregated polyureas (PU) have received considerable interest due to their use as tough, impact-resistant coatings. Polyureas are favored for these applications due to their mechanical strain rate sensitivity and energy dissipation. Predicting and tailoring the mechanical response of PU remains challenging due to the complex interaction between its elastomeric and glassy phases. To elucidate the role of PU microstructure on its mechanical properties, we developed a finite element modeling framework in which each phase is represented by a volume fraction within a representative volume element (RVE). Critically, we used separate constitutive models to describe the elastomeric and glassy phases. We developed a plasticity-driven breakdown process in which we model the glassy phase disaggregating into a new phase. The overall contribution of each phase at a material point is determined by their respective volume fractions within the RVE. We applied our modeling methods to two compositions of PU with differing elastomeric segment lengths derived from oligoether diamines, Versalink P650 and P1000. Our simulations show that a combination of microstructural differences and elastomeric phase properties accounts for the difference in mechanical response between P650 and P1000. We show our model’s ability to predict PU behavior in various loading conditions, including low-rate cyclic loading and monotonic loading over a wide range of strain rates. Our model produces microstructure transformations that mirror those indicated by small-angle X-ray scattering (SAXS) experiments. Fourier transform analysis of our RVEs reveals glassy phase fibrillation due to deformation, a finding consistent with SAXS experiments.

相分离聚脲（PU）由于可用作坚韧的抗冲击涂层而备受关注。聚氨酯因其机械应变速率敏感性和能量耗散性而受到这些应用的青睐。由于聚氨酯的弹性体相和玻璃相之间存在复杂的相互作用，因此预测和定制聚氨酯的机械响应仍然具有挑战性。为了阐明聚氨酯微观结构对其机械性能的影响，我们开发了一个有限元建模框架，其中每个相都由代表体积元素（RVE）中的体积分数来表示。重要的是，我们使用不同的构成模型来描述弹性体相和玻璃相。我们开发了一种塑性驱动的分解过程，其中我们模拟了玻璃相分解为新相的过程。各相在材料点的总体贡献由它们在 RVE 中各自的体积分数决定。我们将建模方法应用于低聚醚二胺（Versalink P650 和 P1000）制成的两种具有不同弹性段长度的聚氨酯成分。模拟结果表明，P650 和 P1000 的机械响应差异是由微观结构差异和弹性体相特性共同造成的。我们展示了我们的模型在各种加载条件下预测聚氨酯行为的能力，包括低速率循环加载和大范围应变速率下的单调加载。我们的模型所产生的微观结构变化与小角 X 射线散射（SAXS）实验所显示的结果一致。对我们的 RVE 进行的傅立叶变换分析揭示了玻璃相因变形而产生的纤维化，这一发现与 SAXS 实验一致。

International Journal of Plasticity

Towards a reliable nanohardness-dose correlation of ion-irradiated materials from nanoindentation tests: A case study in proton-irradiated vanadium.

Chen Shang, Yuan Jiuxi, Wang Shumin, Mei Luyao, Yan Jiaohui, Li Lei, Zhang Qiuhong, Zhu Zhixi, Lv Jin, Xue Yunfei, Dou Yankun, Xiao Xiazi, Guo Xun, Jin Ke

doi:10.1016/j.ijplas.2023.103804

通过纳米压痕测试实现离子辐照材料的可靠纳米硬度-剂量相关性：质子辐照钒案例研究。

Nanoindentation has been commonly used for evaluating the hardening effects of ion-irradiated materials. Nonetheless, establishing a reliable correlation between the hardness and irradiation dose is never trivial, due to not only the intrinsic analytical challenges of this technique, such as size effects, pile-up effects, etc., but also the fact that the irradiation dose is usually uneven inside the stress volume under the indenter, especially near the depth of dose peak. In the present work, the hardening in pure V irradiated with 1 MeV proton at various fluences is investigated by using nanoindentation tests, combined with the characterization of both irradiation defects and dislocations of the indented material. Under the cross-sectional indentation, we demonstrate that the nanohardness-dose correlation can be unified from the samples irradiated to different fluences and at different depths on each sample, as long as the lateral spanning of indenter is carefully considered. Crystal-plasticity finite-element-modeling simulation results can well describe the measured hardening-dose correlation, as well as the observed features on the change in strained fields and pile-up effects after irradiations. Moreover, the measured hardness is further corrected for the dose-dependent pile-up based on the surface profiling, and the indentation size effects based on surface indentation tests for deeper indentation depth, to reach a reliable connection between the hardening effects and the irradiation dose. Furthermore, microstructural characterization of the indented materials shows the pinning of dislocation by irradiation defects and the sweeping of those defects during dislocation migration. Molecular dynamics results suggest that the drag of loops by edge dislocations might cause the annihilation or aggregation of small loops, which could be responsible for the lower density but the larger size of irradiation loops in the strained region.

纳米压痕常用于评估离子辐照材料的硬化效应。然而，要在硬度和辐照剂量之间建立可靠的相关性绝非易事，这不仅是由于该技术固有的分析难题，如尺寸效应、堆积效应等，还由于辐照剂量在压头下的应力体积内通常是不均匀的，尤其是在剂量峰值深度附近。在本研究中，通过纳米压痕试验，结合辐照缺陷和压痕材料位错的表征，研究了在不同通量下用 1 MeV 质子辐照的纯 V 的硬化情况。在横截面压痕下，我们证明了只要仔细考虑压头的横向跨度，就能从每个样品上的不同通量和不同深度的辐照中统一出纳米硬度与剂量的相关性。晶体塑性有限元模型模拟结果可以很好地描述测量到的硬化-剂量相关性，以及观察到的辐照后应变场变化和堆积效应特征。此外，还根据表面轮廓分析进一步校正了与剂量相关的堆积效应，并根据表面压痕测试进一步校正了压痕深度的压痕尺寸效应，从而在硬化效应与辐照剂量之间建立了可靠的联系。此外，压痕材料的微观结构特征显示了辐照缺陷对位错的钉扎作用，以及位错迁移过程中对这些缺陷的扫描。分子动力学结果表明，边缘位错对环状体的拖拽可能导致小环状体的湮灭或聚集，这可能是应变区辐照环状体密度较低但尺寸较大的原因。

Thin-Walled Structures

Energy absorption characteristics of aluminum foam-filled corrugated tube under axial compression loading

Yan Song, Jiang Yi, Deng Yueguang, Cai Yunlong

doi:10.1016/j.tws.2023.111333

铝泡沫填充波纹管在轴向压缩载荷下的能量吸收特性

To improve the energy absorption characteristics of thin-walled structures and reduce the initial peak compression force and load fluctuation, a novel aluminum foam-filled corrugated tube was proposed in this study. Finite element model validated by quasi-static compression experiments was adopted to investigate the crashworthiness performances of aluminum foam-filled corrugated tubes and their combined energy-absorbing structures. The effects of structure parameters including corrugation radius, wall thickness, corrugation length and corrugation radius increments on axial compression characteristics were investigated through finite element analysis. The results showed that compared with aluminum foam-filled straight tubes, the initial peak compression force of aluminum foam filled corrugated tube was reduced by 22.87%, the compression force efficiency was increased by 6.69% and the load fluctuation was reduced by 17.94%. The smaller the values of corrugation radius, wall thickness and corrugation length, the smaller the initial peak compression force; Because the corrugation radius had a great effect on the peak compression force, the order that the corrugations were compressed into folds can be controlled by designing the corrugation radius; In view of the peak and valley values of compression force, an innovative combination of single tubes with different △H was obtained, which had better energy absorption performance. Compared with a single aluminum foam-filled corrugated tube, the compression force efficiency of the combined structure (△H: 0-5-10) was increased by 18.15% and the load fluctuation was reduced by 33.60%. The research results can provide a reference for the design and optimization of energy-absorbing devices.

为了改善薄壁结构的能量吸收特性，降低初始峰值压缩力和载荷波动，本研究提出了一种新型铝泡沫填充波纹管。采用经准静态压缩实验验证的有限元模型，研究了泡沫填充铝波纹管及其组合吸能结构的耐撞性能。通过有限元分析研究了波纹半径、壁厚、波纹长度和波纹半径增量等结构参数对轴向压缩特性的影响。结果表明，与泡沫铝填充直管相比，泡沫铝填充波纹管的初始峰值压缩力降低了 22.87%，压缩力效率提高了 6.69%，载荷波动降低了 17.94%。波纹半径、壁厚和波纹长度的值越小，初始峰值压缩力越小；由于波纹半径对峰值压缩力的影响很大，因此可以通过设计波纹半径来控制波纹被压缩成褶皱的顺序；根据压缩力的峰值和谷值，创新性地得到了不同△H 的单管组合，具有更好的能量吸收性能。与单一的铝泡沫填充波纹管相比，组合结构（△H：0-5-10）的压缩力效率提高了 18.15%，载荷波动降低了 33.60%。研究结果可为吸能装置的设计和优化提供参考。

Simulation of SMA-based engineering applications considering large displacement and rotation, thermomechanical coupling and partial phase transformation

Kundu Animesh, Banerjee Atanu

doi:10.1016/j.tws.2023.111338

考虑到大位移和旋转、热机械耦合和部分相变的基于 SMA 的工程应用模拟

Shape memory alloys (SMAs) undergo large recoverable deformation due to their inherent diffusionless martensitic phase transformation. Two factors need to be taken into account to incisively emulate the behaviour of SMA based structures: (i) consideration of large displacement and rotation (LDR) effect, and (ii) capturing the consequence of transformation induced material level coupling. In this study, both these effects are apprehended by extending the infinitesimal strain-based constitutive model of SMA as proposed by Lagoudas et al. (2012), assuming small elastic strain but with finite inelastic strain. To preclude any spurious stress generation out of large rotation, the Jaumann stress rate is used, and incremental objectivity for finite rotation between two successive time instants is conserved by rotating the strain increment and spin tensor to the rotation-independent mid-point configuration following Hughes-Winget (Hughes and Winget, 1980) algorithm. In addition, the contribution of thermoelastic and latent heat evolved during transformation is taken into consideration in the thermal equilibrium equation. Moreover, the effect of partial phase transformation yielding minor hysteresis loop has also been captured. The equilibrium equation is expressed in the current configuration following the Updated Lagrangian formulation. The mechanical and thermal equilibrium equations are solved concurrently in block matrix form using the Newton–Raphson (NR) iterative technique, considering the coupling terms resulting from the phase transformation. The efficacy and robustness of the developed finite element model are corroborated through various practical applications of SMA-based members, e.g., SMA ring, SMA-actuated beam, morphing of corrugated airfoil, orthodontic palatal expander, compliant gripper, undergoing LDR while subjected to different thermomechanical loading conditions. The combined effects of LDR along with thermomechanical coupling yield a stiffening behaviour during loading and sluggish response at the time of thermal recovery.

形状记忆合金（SMA）由于其固有的无扩散马氏体相变，会产生较大的可恢复变形。要准确模拟基于 SMA 的结构行为，需要考虑两个因素：(i) 考虑大位移和旋转 (LDR) 效应；(ii) 捕获转化诱导的材料级耦合的后果。在本研究中，通过扩展 Lagoudas 等人（2012 年）提出的基于无穷小应变的 SMA 构成模型，假设弹性应变较小，但非弹性应变有限，从而理解了这两种效应。为了排除大旋转产生的任何虚假应力，使用了 Jaumann 应力率，并按照 Hughes-Winget 算法（Hughes 和 Winget，1980 年）将应变增量和自旋张量旋转到与旋转无关的中点配置，从而保持了两个连续时间点之间有限旋转的客观增量。此外，热平衡方程还考虑了转化过程中产生的热弹性和潜热。此外，还考虑了部分相变产生小滞后环的影响。平衡方程是按照最新的拉格朗日公式在当前配置中表示的。考虑到相变产生的耦合项，采用牛顿-拉斐森（NR）迭代技术，以块矩阵形式同时求解机械平衡方程和热平衡方程。通过各种基于 SMA 的实际应用，如 SMA 环、SMA 驱动梁、波纹翼面变形、正畸腭部扩张器、顺应式夹具等，证实了所开发有限元模型的有效性和稳健性，并在不同的热机械加载条件下进行 LDR。LDR 与热机械耦合的综合效应导致加载期间的僵化行为和热恢复时的迟缓响应。

Effect of high-frequency induction weld seam on the deformation of M1700 ultra-high strength steel shell structures considering residual tensile stress

Yang Fan, Wen Tong, Wang Qiufeng, Zhang Longzhu, Liu Hailong, Zhou Yang

doi:10.1016/j.tws.2023.111340

考虑残余拉应力的高频感应焊缝对 M1700 超高强度钢壳结构变形的影响

The feasible cold forming procedure to massively manufacture ultra-high strength steel (UHSS) light-weighting profiles so far in industrial fields consists of roll forming, welding, cutting and bending. To reveal the role the high-frequency induction weld (HFIW) line plays in the subsequent plastic forming, a serials of deliberately designed collapse tests of the shell structures taken from M1700 roof rail pillar with a wall-thickness of 2 mm and triangle cross-section were conducted. Real geometries and inhomogeneous material properties of the weld seam and heat-affected zone (HAZ), together with the residual tensile stresses within the weld seam after HFIW, were fully considered in the numerical simulation. The Brozoo's modified CL damage model and Oyane damage model were employed and compared. The results show that the deformation resistance of the shell structures is modified by the material accumulation around the HFIW seams during the collapse tests. The cracks mainly occur within the critical HAZ outside the tube and the temper softening zone inside the tube under the action of softening effect in the HAZ of M1700 steel. The residual tensile stresses increase the crack probability of weld seams. The predicting accuracy of fracture location of the Oyane damage model is higher than that of the Brozoo's modified CL damage model.

迄今为止，在工业领域大规模制造超高强度钢（UHSS）轻质型材的可行冷成型程序包括辊压、焊接、切割和弯曲。为了揭示高频感应焊接（HFIW）线在后续塑性成形中的作用，我们对取自 M1700 车顶轨支柱的壁厚为 2 毫米、横截面为三角形的壳体结构进行了一系列特意设计的坍塌试验。数值模拟充分考虑了焊缝和热影响区（HAZ）的实际几何形状和不均匀材料特性，以及高频无缝焊接后焊缝内的残余拉应力。采用了 Brozoo 修正的 CL 损伤模型和 Oyane 损伤模型，并进行了比较。结果表明，在坍塌试验过程中，壳体结构的抗变形能力受到 HFIW 焊缝周围材料堆积的影响。在 M1700 钢 HAZ 软化效应的作用下，裂纹主要出现在管外临界 HAZ 和管内回火软化区。残余拉应力增加了焊缝的裂纹概率。Oyane 损伤模型对断裂位置的预测精度高于 Brozoo 修正的 CL 损伤模型。

Graphene/h-BN hybrid van der Waal structures with high strength and flexibility: a nanoindentation investigation

Yang Youzhe, Ma Jun, Yang Jie, Zhang Yingyan

doi:10.1016/j.tws.2023.111341

具有高强度和柔韧性的石墨烯/h-BN 混合范德华结构：纳米压痕研究

Two-dimensional nanomaterials, such as graphene and h-BN have been widely used as reinforcing fillers for polymer-based impact protection materials, phase change materials (PCM) or thermal interface materials (TIM) due to its exceptional high mechanical strength and high thermal conductivity. But the mechanical properties of graphene/h-BN (GBN) van der Waals (vdW) heterostructures remain largely unexplored. Herein we carry out intensive nanoindentation tests on GBN by using molecular dynamics simulations as well as finite element analysis to investigate its mechanical properties, its fracture mechanisms as well as the effective manipulation techniques for force and deformation. Compared with its homogeneous counterparts (pure graphene or pure h-BN), the heterogenous GBN possess excellent performance in resisting bending deformation in terms of the indentation load and depth. The size-dependent performance of GBN can be effectively manipulated by hydrogenation in the middle graphene and layer number, except the composition diffusion interface. This comprehensive study confirms that the high strength and high flexibility of GBN endow it with great potential in the applications of impact protection and thermal management in PCM and TIM.

石墨烯和 h-BN 等二维纳米材料因其卓越的高机械强度和高导热性，已被广泛用作聚合物基抗冲击保护材料、相变材料 (PCM) 或热界面材料 (TIM) 的增强填料。但是，石墨烯/h-BN（GBN）范德华（vdW）异质结构的机械性能在很大程度上仍未得到探索。在此，我们通过分子动力学模拟和有限元分析，对 GBN 进行了密集的纳米压痕测试，以研究其力学性能、断裂机制以及力和变形的有效操控技术。与同质材料（纯石墨烯或纯 h-BN）相比，异质 GBN 在抵抗弯曲变形方面具有优异的性能，包括压痕载荷和深度。除成分扩散界面外，GBN 的尺寸性能可通过中间石墨烯和层数的氢化得到有效控制。这项综合研究证实，GBN 的高强度和高柔韧性使其在 PCM 和 TIM 的抗冲击保护和热管理方面具有巨大的应用潜力。

Experimental study on S700 T-stub in heating and cooling during fire

Dhamane Shravani, Mushahary Suman Kumar, Singh Konjengbam Darunkumar

doi:10.1016/j.tws.2023.111342

S700 T 型管在火灾中加热和冷却的实验研究

In this paper, experimental investigations were carried out to assess the strength of S700 steel material and T-stub made from S700 steel in heating and cooling during fire with an emphasis on cooling stage fire (decreasing temperature). T-stub is a simple idealization of tension zone in bolted connection as T-shaped joint. In total, 17 coupons were tested in room temperature, growth (growing/ increasing temperature), cooling and postfire phases. It was observed from the tensile test data, that the growth phase properties were not similar as the cooling phase properties, however, about 90% of strength regained at the end of cooling phase, (i.e., in postfire specimens). 22 T-stubs of two geometric configurations were tested for axial capacity in heating and cooling during fire. In both the geometric configuration, the mode of failure at room temperature changed to other modes at elevated temperatures. The mode of failure at elevated temperature depended on the relative strength of T-stub and the bolts. The experimental results were compared with existing codal provisions – Eurocode 3 and AISC 360. It was found that the Eurocode prediction was close to the experimental results, while AISC prediction was highly conservative, which might be attributed to the non-consideration of bolt strength (proportionate reduction in strength due to fire) directly during the strength prediction.

本文进行了实验研究，以评估 S700 钢材料和由 S700 钢制成的 T 型管在火灾期间加热和冷却时的强度，重点是冷却阶段火灾（温度降低）。T 形管是将螺栓连接中的拉伸区简单理想化为 T 形连接。共有 17 个试样在室温、增长（温度增长/升高）、冷却和火灾后阶段进行了测试。从拉伸试验数据中可以看出，增长阶段的特性与冷却阶段的特性并不相似，但在冷却阶段结束时（即熄火后试样），强度恢复了约 90%。对两种几何结构的 22 根 T 形管进行了火灾期间加热和冷却轴向承载力测试。在这两种几何结构中，室温下的失效模式在高温下会转变为其他模式。高温下的破坏模式取决于 T 形柱和螺栓的相对强度。实验结果与现有的规范条款--Eurocode 3 和 AISC 360 进行了比较。结果发现，Eurocode 的预测结果与实验结果接近，而 AISC 的预测结果则非常保守，这可能是由于在强度预测过程中没有直接考虑螺栓强度（火灾导致强度按比例降低）。

Mechanical design and energy absorption performances of novel plate-rod hybrid lattice structures

Cui Zhuang, Zhao Jiayun, Xu Rong, Ding Yuanyuan, Sun Zhengping

doi:10.1016/j.tws.2023.111349

新型板棒混合晶格结构的机械设计和能量吸收性能

Hybrid lattice structures, integrating diverse structural components from fundamental lattice topologies, have attracted significant attention for their exceptional mechanical properties encompassing elastic modulus, yield stress, and energy absorption. To amalgamate the lightweight characteristics of rod structures with the robust mechanical properties of plate structures, a novel plate-rod hybrid lattice (PRHL) with controllable geometrical parameters and higher energy absorption was proposed and fabricated via the Selective Laser Sintering technique. In the PRHL design, the hybrid rod structure, interlinked with the center of each surface of the semi-open Octet plate lattice (SOPL), mutually provides support and deformation constraints. To identify the mechanical properties of PRHL, quasi-static uniaxial compression tests of PRHL samples sintered by Polylactic Acid powder were carried out. In comparison to SOPL, the newly proposed PRHL demonstrates an approximate 13.4% improvement in initial crush stress and an 18.5% increase in specific energy absorption capacity. Furthermore, numerical simulations incorporating the effect of printing orientation were performed to analyze the deformation mechanism of the PRHL structures. The present study also underscores the capacity to fine-tune the mechanical properties of PRHLs by regulating the plate thickness, rod diameter and excavated hole diameter.

混合晶格结构集成了基本晶格拓扑结构中的各种结构组件，因其包括弹性模量、屈服应力和能量吸收在内的优异机械性能而备受关注。为了将杆状结构的轻质特性与板状结构的坚固机械特性相结合，我们提出了一种几何参数可控、能量吸收能力更强的新型板杆混合晶格（PRHL），并通过选择性激光烧结技术进行了制造。在 PRHL 设计中，混合杆结构与半开放式八面体板晶格（SOPL）每个表面的中心相互连接，相互提供支撑和变形约束。为了确定 PRHL 的机械性能，对用聚乳酸粉末烧结的 PRHL 样品进行了准静态单轴压缩试验。与 SOPL 相比，新提出的 PRHL 的初始压应力提高了约 13.4%，比能量吸收能力提高了 18.5%。此外，还结合印刷方向的影响进行了数值模拟，以分析 PRHL 结构的变形机制。本研究还强调了通过调节板厚、杆直径和挖孔直径来微调 PRHL 机械性能的能力。

来源：复合材料力学仿真Composites FEM

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