【新文速递】2023年10月2日固体力学SCI期刊最新文章

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今日更新：Mechanics of Materials 1 篇，International Journal of Plasticity 2 篇

Mechanics of Materials

Conceptual design and analysis of novel hybrid auxetic stents with superior expansion

M.M.Zamani Alireza, Etemadi Ehsan, Bodaghi Mahdi, Hu Hong

doi:10.1016/j.mechmat.2023.104813

新型混合辅助支架的概念设计与分析

This paper presents a conceptual design and finite element (FE) simulation of a novel class of negative Poisson's ratio (NPR) stents with hybrid auxetic structures fabricated by FDM 3D printing technology. The desired structures were first designed in a planar form by a combination of re-entrant, star-shaped, and chiral unit-cells (UCs) but with a difference in the way of connecting UCs to each other. A planar form of the designed stent was 3D printed with thermoplastic polyurethane (TPU) filaments. Then, its mechanical behaviors under quasi-static tensile loading was analysed by the FE method and experimental testing. A good agreement was observed between the FE method and the experiment, and achievement of a significant NPR of −2.3 was revealed. By converting the planar structure into the shape of a stent, the stent expansion and its function were further investigated using the developed FE method based on a complete model consisting of a balloon, plaque, artery, and blood pressure. The results showed that the designed stent has a diameter increase of 96% and 93% at the end of the loading and unloading processes, respectively, which is acceptable according to previous studies. In addition, the distribution of stress in the artery, plaque, and stent and the phenomena of radial and longitudinal recoil, dogboning, and foreshortening of the stent were also investigated. The study revealed that the designed stent could be used as the next generation of polymer stents for vascular diseases in biomedical applications.

本文介绍了一种新型负泊松比（NPR）支架的概念设计和有限元（FE）模拟，该支架采用 FDM 三维打印技术制造，具有混合辅助结构。所需的结构首先设计成平面形式，由重心形、星形和手性单元细胞（UCs）组合而成，但 UCs 之间的连接方式有所不同。使用热塑性聚氨酯（TPU）长丝对所设计支架的平面形状进行了三维打印。然后，通过有限元法和实验测试分析了支架在准静态拉伸载荷下的力学行为。结果表明，FE 方法与实验结果之间具有良好的一致性，并取得了-2.3 的显著 NPR 值。通过将平面结构转换为支架形状，使用所开发的基于由球囊、斑块、动脉和血压组成的完整模型的 FE 方法进一步研究了支架的膨胀及其功能。结果表明，设计的支架在加载和卸载过程结束时直径分别增加了 96% 和 93%，这在以往的研究中是可以接受的。此外，还研究了动脉、斑块和支架中的应力分布，以及支架的径向和纵向反冲、犬骨化和前缩现象。研究表明，所设计的支架可作为下一代聚合物支架用于生物医学领域的血管疾病治疗。

International Journal of Plasticity

A unified viscoelastic model of progressive damage and failure for solid propellants

Wubuliaisan M., Wu Yanqing, Duan Hongzheng, Hou Xiao

doi:10.1016/j.ijplas.2023.103765

固体推进剂渐进损伤和失效的统一粘弹性模型

A general viscoelastic model incorporating the progressive damage evolution and failure criterion is developed for solid propellants across a wide range of temperatures (223K to 333K) and strain rates (2.38 × 10−4 /s to 4.76 × 10−2/s). (i) The progressive damage evolution, characterized by continuous void cavitation and growth, is linked to a macroscopic damage variable derived from a simple damage potential threshold, making it possible to determine the microstructural damage from experimental data. (ii) The failure criterion introduces two microstructural ingredients: the strain energy density, which accounts for both the glassy and rubbery failure of the polymer matrix, capturing brittle and ductile fracture modes at low and high temperatures respectively; and the void volume limit accounts for interface debonding, a process of particle detachment from the matrix. The implementation of the model effectively predicts the damage response and failure strains under uniaxial tension, cyclic and complex loading as well as superimposed pressure. Results reveal strong temperature/strain-rate dependency in the tensile strength, volume dilatation, and failure strains. Given that the model unifies progressive damage with ultimate failure and requires only a few model parameters, it assists in establishing a fracture criterion for the nonlinear fracture behavior of viscoelastic materials.

为固体推进剂开发了一个通用粘弹性模型，其中包含渐进式损伤演变和失效标准，适用于各种温度（223K 至 333K）和应变率（2.38 × 10-4 /s 至 4.76 × 10-2/s）.(i) 以连续空洞化和增长为特征的渐进式损伤演变与由简单损伤势阈值推导出的宏观损伤变量相关联，从而可以根据实验数据确定微观结构损伤。(ii) 失效准则引入了两种微观结构成分：应变能密度，它考虑了聚合物基体的玻璃态和橡胶态失效，分别捕捉了低温和高温下的脆性和韧性断裂模式；空隙体积极限考虑了界面脱粘，即粒子从基体脱离的过程。该模型的实施可有效预测单轴拉伸、循环和复合加载以及叠加压力下的破坏响应和破坏应变。结果表明，拉伸强度、体积膨胀和破坏应变都与温度/应变速率密切相关。鉴于该模型将渐进破坏与最终破坏统一起来，且只需少量模型参数，因此有助于建立粘弹性材料非线性断裂行为的断裂准则。

Tension-compression asymmetry of metastable austenitic stainless steel studied by in-situ high-energy X-ray diffraction

Bönisch Matthias, Barriobero-Vila Pere, Dhekne Pushkar Prakash, Stark Andreas, Schell Norbert, Ungár Tamás, Requena Guillermo, Seefeldt Marc

doi:10.1016/j.ijplas.2023.103767

通过原位高能 X 射线衍射研究可蜕变奥氏体不锈钢的拉伸-压缩不对称性

This work studies the tension-compression asymmetry (TCA) of metastable austenitic stainless steel (MASS) in uniaxial loading depending on temperature. In-situ high-energy X-ray diffraction was used to simultaneously probe phase fractions, transformation kinetics, crystallographic texture, lattice strains, strain and stress partitioning between austenite and martensites during quasi-static tensile and compressive deformation at 24°C, 60°C and 100°C. Complementary relaxed-constraint crystal plasticity simulations and calculations of the mechanical driving force related to the formation of α’ and ε martensites were performed. At 24°C, martensitic transformations (MTs) prevail, while at 100°C dislocation slip is the dominant deformation mechanism for both load senses. Macroscopic stress-strain response and transformation behaviour exhibit TCA, with compression promoting the conversion of ε into α’. Transformation kinetics were analysed in relation to shear banding and the geometric alignment of ε lamellas depending on load sense and temperature. A strong TCA was found for crystallographic texture, bearing signatures of grain rotation due to plastic slip and of MT in case of austenite (γ). For both load senses, the relative strengths of austenite and martensite texture fibres were related to the driving force anisotropy for α’ formation calculated based on the phenomenological theory of martensite crystallography. Texture evolution of α’ is largely controlled by the MT itself, not by grain rotation. Analysis of differently oriented austenite grain families revealed a pronounced TCA of the lattice strains, linked to the γ → ε MT. This was found to be a direct consequence of driving force and volume change related to ε formation. Furthermore, stress is shared differently between austenite and martensites in tension vs. in compression. γ hardens more and hence carries a larger portion of the total stress in compression than in tension. The origin for this TCA could be found in the elasto-plastic accommodation of the volume change related to α’ formation. These findings can aid the development of new material laws for MASSs that are sensitive to load-sense and temperature for advanced forming simulations.

这项工作研究的是单轴加载时可蜕变奥氏体不锈钢（MASS）的拉伸-压缩不对称（TCA）取决于温度。在 24°C、60°C 和 100°C 的准静态拉伸和压缩变形过程中，采用原位高能 X 射线衍射同时探测奥氏体和马氏体之间的相分数、转变动力学、晶体学纹理、晶格应变、应变和应力分配。此外，还进行了松弛约束晶体塑性模拟，并计算了与α'和ε马氏体形成有关的机械驱动力。在 24°C 时，马氏体转变（MTs）占主导地位，而在 100°C 时，位错滑移是两种载荷作用下的主要变形机制。宏观应力应变响应和转变行为显示出 TCA，压缩促进了 ε 向 α' 的转化。分析了转化动力学与剪切带以及ε薄片几何排列的关系，这取决于载荷感和温度。发现结晶纹理具有很强的 TCA，带有塑性滑移引起的晶粒旋转和奥氏体（γ）MT 的特征。对于这两种载荷感，奥氏体和马氏体纹理纤维的相对强度与根据马氏体结晶现象学理论计算出的α'形成的驱动力各向异性有关。α'的纹理演变在很大程度上受马氏体本身而非晶粒旋转的控制。对不同取向奥氏体晶粒族的分析表明，晶格应变具有明显的 TCA，与 γ → ε MT 有关。这是与ε形成相关的驱动力和体积变化的直接结果。此外，奥氏体和马氏体在拉伸和压缩时分担应力的方式不同。γ的硬化程度更高，因此在压缩时比在拉伸时承载的总应力更大。α'形成相关的体积变化的弹塑性适应性可能是这种TCA的起源。这些发现有助于为 MASS 开发新的材料定律，这些定律对载荷感应和温度敏感，可用于先进的成型模拟。

来源：复合材料力学仿真Composites FEM

【新文速递】2023年10月4日固体力学SCI期刊最新文章

今日更新：Computer Methods in Applied Mechanics and Engineering 1 篇，Thin-Walled Structures 2 篇Computer Methods in Applied Mechanics and EngineeringA low-rank isogeometric solver based on Tucker tensorsMontardini M., Sangalli G., Tani M.doi:10.1016/j.cma.2023.116472基于塔克张量的低阶等距求解器We propose an isogeometric solver for Poisson problems that combines (i) low-rank tensor techniques to approximate the unknown solution and the system matrix, as a sum of a few terms having Kronecker product structure, (ii) a Truncated Preconditioned Conjugate Gradient solver to keep the rank of the iterates low, and (iii) a novel low-rank preconditioner, based on the Fast Diagonalization method where the eigenvector multiplication is approximated by the Fast Fourier Transform. Although the proposed strategy is written in arbitrary dimension, we focus on the three-dimensional case and adopt the Tucker format for low-rank tensor representation, which is well suited in low dimension. We show by numerical tests that this choice guarantees significant memory saving compared to the full tensor representation. We also extend and test the proposed strategy to linear elasticity problems.我们针对泊松问题提出了一种等几何求解器，该求解器结合了：(i) 低阶张量技术，将未知解和系统矩阵近似为具有克朗克积结构的几个项的总和；(ii) 截断预处理共轭梯度求解器，以保持较低的迭代秩；(iii) 基于快速对角化方法的新型低阶预处理器，其中特征向量乘法近似于快速傅立叶变换。虽然所提出的策略可以在任意维度下编写，但我们将重点放在三维情况下，并采用塔克格式来表示低秩张量，这种格式非常适合低维度。我们通过数值测试表明，与完整的张量表示法相比，这种选择能显著节省内存。我们还将提出的策略扩展到线性弹性问题并进行了测试。Thin-Walled StructuresA Unified Dynamic Model and Vibration Suppression for Moving Corrugated Sandwich Panels with General BoundariesZhou Kai, You Taiwen, Gong Dao, Zhou Jinsongdoi:10.1016/j.tws.2023.111248带一般边界的移动波纹夹芯板的统一动态模型与振动抑制The sandwich plate structures with corrugated cores are extensively utilized in engineering cases, such as the panels in railway vehicles, aerospace flight vehicles and so on. These sandwich plates in service can be simplified as the axially moving panel structures in the dynamic modeling. To research the dynamic behaviors of moving corrugated sandwich (CS) panels, an equivalent model is utilized. The energy method combined with penalty factor approach is applied to deduce the energy functions of the panel structure, and the corresponding formulations are further deduced based on the Hamilton's principle. Based on the proposed model, the examples with classical and elastic edge boundaries can be considered. Several computational examples are implemented to verify the present formulations, and satisfactory consistency can be observed. Meanwhile, impacts of several structural parameters on the dynamic and stability properties of the CS panel are investigated. To suppress the vibration of CS panels, the negative capacitance piezoelectric shunt damping circuit (PSDC) is further adopted. The impacts of the velocity parameter on the optimal values of the PSDC are discussed and calculated results demonstrate that dynamic responses of moving CS panels are satisfactorily attenuated by the proposed control strategy.带波纹芯材的夹层板结构在工程案例中得到广泛应用，如铁路车辆、航空飞行器等的面板。在动态建模中，这些服役中的夹芯板可简化为轴向移动的面板结构。为了研究移动波纹夹层板（CS）的动态行为，我们采用了等效模型。采用能量法结合惩罚因子法来推导板结构的能量函数，并根据汉密尔顿原理进一步推导出相应的公式。根据提出的模型，可以考虑经典和弹性边缘边界的示例。通过几个计算实例验证了本公式，并观察到了令人满意的一致性。同时，研究了几个结构参数对 CS 面板动态和稳定性能的影响。为了抑制 CS 面板的振动，进一步采用了负电容压电并联阻尼电路（PSDC）。讨论了速度参数对 PSDC 最佳值的影响，计算结果表明，采用所提出的控制策略后，移动 CS 面板的动态响应得到了令人满意的抑制。A star-shaped tubular structure with multiple-directional auxetic effectLang Jian Ping, Han Dong, Zhang Xue Gang, Jiang Wei, Zhang Yi, Ni Xi hai, Hao Jian, Teng Xing Chi, Ren Xindoi:10.1016/j.tws.2023.111247具有多向辅助效应的星形管状结构A majority of tubular structures have been widely studied due to their superior mechanical performance. Existing works on star-shaped tubular structures have focused on improving their stability and energy absorption performance. This paper proposes a novel star-shaped tubular lattice structure (STL), which not only possesses excellent mechanical properties but also exhibits exceptional auxetic effect. In addition, such structures exhibited two distinct deformation modes under different loading directions. Numerical and experimental studies of the mechanical behavior of the star-shaped tubular structure demonstrated low peak stresses under lateral loading and superior bearing capacity and stability under axial compression. Most importantly, the structure embodied a significant auxetic effect under the direction of both loads. The mechanical performance of the star-shaped tubular structures was investigated by changing wall thickness and angles, which can realize the optimal design. This study enriches the research on star-shaped tubular structures and provides a new perspective and reference for the design of auxetic tubular metamaterials in the future. Furthermore, the star-shaped tubular structure with auxetic behavior has considerable potential for applications in civil engineering and protective fields.大多数管状结构因其卓越的机械性能而被广泛研究。现有关于星形管状结构的研究主要集中在提高其稳定性和能量吸收性能上。本文提出了一种新型星形管状晶格结构（STL），这种结构不仅具有优异的机械性能，还表现出卓越的辅助效应。此外，这种结构在不同加载方向下表现出两种截然不同的变形模式。对星形管状结构力学行为的数值和实验研究表明，该结构在横向加载下具有较低的峰值应力，在轴向压缩下具有出色的承载能力和稳定性。最重要的是，该结构在两种载荷方向上都体现了显著的辅助效应。通过改变壁厚和角度，研究了星形管状结构的力学性能，从而实现了优化设计。这项研究丰富了星形管状结构的研究内容，为今后设计辅助管状超材料提供了新的视角和参考。此外，具有辅助行为的星形管状结构在土木工程和防护领域的应用具有相当大的潜力。来源：复合材料力学仿真Composites FEM